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Chinese Journal of Catalysis
2022, Vol. 43, No. 2
Online: 18 February 2022

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Cover: Cocatalyst modification is a promising strategy to improve the photocatalytic H2-production activity of single-component photocatalysts. Huogen Yu's group from China University of Geosciences (Wuhan) introduced the transition metal Cu into the Pd lattice via a simple NaH2PO2-mediated co-deposition method. Characterization results show that the introduction of Cu weakens the binding strength of Pd towards H atoms, promoting the desorption of H and the H2-production activity. This strategy provides new insights for the development of high-efficiency photocatalysts for hydrogen evolution. Read more about the article on pages 215–225.

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Preface to special issue for the 3rd Chinese Symposium on Photocatalytic Materials (CSPM3) Yu Jiaguo, Yu Changlin, Yu Huogen 2022, 43 (2):  177-177.  DOI: 10.1016/S1872-2067(21)63971-2 Abstract ( 150 )   HTML ( 234 )   PDF (323KB) ( 106 )

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A review on heterogeneous photocatalysis for environmental remediation: From semiconductors to modification strategies Huijie Wang, Xin Li, Xiaoxue Zhao, Chunyan Li, Xianghai Song, Peng Zhang, Pengwei Huo, Xin Li 2022, 43 (2):  178-214.  DOI: 10.1016/S1872-2067(21)63910-4 Abstract ( 567 )   HTML ( 49 )   PDF (14003KB) ( 1107 )   Heterogeneous photocatalysis, an advanced oxidation process, has garnered extensive attention in the field of environmental remediation because it involves the direct utilization of solar energy for the removal of numerous pollutants. However, the application of heterogeneous photocatalysis in environmental remediation has not achieved the expected consequences due to enormous challenges such as low photocatalytic efficiencies and high costs of heterogeneous photocatalysts in large-scale practical applications. Furthermore, pollutants in the natural environment, including water, air, and solid phases, are diverse and complex. Therefore, extensive efforts should be made to better understand and apply heterogeneous photocatalysis for environmental remediation. Herein, the fundamentals of heterogeneous photocatalysis for environmental remediation are introduced. Then, potential semiconductors and their modification strategies for environmental photocatalysis are systematically presented. Finally, conclusions and prospects are briefly summarized, and the direction for the future development of environmental photocatalysis is explored. This review may provide reference directions toward understanding, researching, and designing photocatalytic remediation systems for various environmental pollutants.

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Palladium-copper nanodot as novel H2-evolution cocatalyst: Optimizing interfacial hydrogen desorption for highly efficient photocatalytic activity Jiachao Xu, Duoduo Gao, Huogen Yu, Ping Wang, Bichen Zhu, Linxi Wang, Jiajie Fan 2022, 43 (2):  215-225.  DOI: 10.1016/S1872-2067(21)63830-5 Abstract ( 296 )   HTML ( 14 )   PDF (2420KB) ( 209 )   Supporting Information Noble metal palladium (Pd) is well-known as excellent photocatalytic cocatalyst, but its strong adsorption to hydrogen causes its limited H2-evolution activity. In this study, the transition metal Cu was successfully introduced into the metallic Pd to weaken its hydrogen-adsorption strength to improve its interfacial H2-evolution rate via the Pd-Cu alloying effect. Herein, the ultrasmall Pd100-xCux alloy nanodots (2-5 nm) as a novel H2-evolution cocatalyst were integrated with the TiO2 through a simple NaH2PO2-mediated co-deposition route. The resulting Pd100-xCux/TiO2 sample shows the significantly enhanced photocatalytic H2-generation performance (269.2 μmol h -1), which is much higher than the bare TiO2. Based on in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and density functional theory (DFT) results, the as-formed Pd100-xCux alloy nanodots can effectively promote the separation of photo-generated charges and weak the adsorption strength for hydrogen to optimize the process of hydrogen-desorption process on Pd75Cu25 alloy, thus leading to high photocatalytic H2-evolution activity. Herein, the weakened H adsorption of Pd75Cu25 cocatalyst can be ascribed to the formation of electron-rich Pd after the introduction of weak electronegativity Cu. The present work about optimizing electronic structure for promoting interfacial reaction activity provides a new sight for the development of the highly efficient photocatalysts.

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Effect of calcination temperatures on photocatalytic H2O2-production activity of ZnO nanorods Zicong Jiang, Yong Zhang, Liuyang Zhang, Bei Cheng, Linxi Wang 2022, 43 (2):  226-233.  DOI: 10.1016/S1872-2067(21)63832-9 Abstract ( 329 )   HTML ( 13 )   PDF (1611KB) ( 240 )   Photocatalytic hydrogen peroxide (H2O2) production from O2 and H2O is an ideal process for solar-to-chemical energy conversion. Herein, ZnO nanorods are prepared via a simple hydrothermal method for photocatalytic H2O2 production. The ZnO nanorods exhibit varied performance with different calcination temperatures. Benefiting from calcination, the separation efficiency of photo-induced carriers is significantly improved, leading to the superior photocatalytic activity for H2O2 production. The H2O2 produced by ZnO calcined at 300 °C is 285 μmol L -1, which is over 5 times larger than that produced by untreated ZnO. This work provides an insight into photocatalytic H2O2 production mechanism by ZnO nanorods, and presents a promising strategy to H2O2 production.

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UV-VIS-NIR-induced extraordinary H2 evolution over W18O49/Cd0.5Zn0.5S: Surface plasmon effect coupled with S-scheme charge transfer Wenhua Xue, Hongli Sun, Xiaoyun Hu, Xue Bai, Jun Fan, Enzhou Liu 2022, 43 (2):  234-245.  DOI: 10.1016/S1872-2067(20)63783-4 Abstract ( 194 )   HTML ( 8 )   PDF (1864KB) ( 168 )   Supporting Information In this work, a novel plasmon-assisted UV-vis-NIR-driven W18O49/Cd0.5Zn0.5S heterostructure photocatalyst was obtained by a facile ultrasonic-assisted electrostatic self-assembly strategy. The hybrid exhibits extraordinary H2 evolution activity of 147.7 mmol∙g -1∙h -1 at room temperature due to the efficient charge separation and expanded light absorption. Our investigation shows that the unique Step-scheme (S-scheme) charge transfer and the ‘hot electron’ injection are both responsible for the extraordinary H2 evolution process, depending on the wavelength of the incident light. Moreover, by accelerating the surface reaction kinetics, the activity can be further elevated to 306.1 mmol∙g -1∙h -1, accompanied by a high apparent quantum yield of 45.3% at 365 ± 7.5 nm. This work provides us a potential strategy for the highly efficient conversion of the solar energy by elaborately combining a nonstoichiometric ratio plasmonic material with an appropriate active photocatalyst.

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Selective CO2 photoreduction to CH4 mediated by dimension-matched 2D/2D Bi3NbO7/g-C3N4 S-scheme heterojunction Kai Wang, Xuezhen Feng, Yangzi Shangguan, Xiaoyong Wu, Hong Chen 2022, 43 (2):  246-254.  DOI: 10.1016/S1872-2067(21)63819-6 Abstract ( 139 )   HTML ( 5 )   PDF (1928KB) ( 203 )   Supporting Information Discovering highly selective catalysts is key to achieve effective CO2 photoreduction to hydrocarbon fuels. In this work, we construct an ultrathin dimension-matched S-scheme Bi3NbO7/g-C3N4 heterostructure, which permits the highly selective photocatalytic reduction of CO2 to CH4, as shown by 13C isotopic measurements. Density functional theory calculations combined with solid-state characterization confirm the electron transfer from g-C3N4 nanosheets to Bi3NbO7, establishing an internal electric field. The internal electric field drives photogenerated electrons from Bi3NbO7 to g-C3N4, as revealed by in-situ X-ray photoelectron spectroscopy, demonstrating the presence of an S-scheme charge transfer path in Bi3NbO7/g-C3N4 heterostructures allowing efficient and selective CO2 photoreduction. As a result, the optimized sample achieved a CH4 evolution rate of 37.59 μmol·g -1·h -1, a ca. 15-fold enhancement compared to ultrathin g-C3N4 nanosheets, and also retained stability after 10 reaction cycles and 40 h of simulated solar irradiation with no sacrificial reagents. The optimized Bi3NbO7/g-C3N4 composites achieve almost 90% selectivity for CH4 production over CO.

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Organic amine surface modified one-dimensional CdSe0.8S0.2-diethylenetriamine/two-dimensional SnNb2O6 S-scheme heterojunction with promoted visible-light-driven photocatalytic CO2 reduction Hui Yang, Jin feng Zhang, Kai Dai 2022, 43 (2):  255-264.  DOI: 10.1016/S1872-2067(20)63784-6 Abstract ( 172 )   HTML ( 5 )   PDF (2565KB) ( 162 )   Achieving a strong redox ability and high visible-light absorption ability in a single semiconductor material is difficult. Designing a heterojunction between two semiconductor materials is a feasible method. The new step (S-scheme) heterojunction can effectively promote the separation and transfer of photogenerated electron-hole pairs and retain strong redox ability. We designed and prepared a CdSe0.8S0.2-diethylenetriamine (DETA)/SnNb2O6 heterostructure material via the solvothermal method. When CdSe0.8S0.2-DETA and SnNb2O6 form an S-scheme heterojunction, 30%CdSe0.8S0.2-DETA/SnNb2O6 exhibits the highest CO production rate (17.31 μmol·g -1·h -1), which is factors of 2.8 and 4.8 higher than that of traditional solvothermal SnNb2O6 (6.2 μmol·g -1·h -1) and CdSe0.8S0.2-DETA (3.6 μmol·g -1·h -1), respectively. X-ray photoelectron spectroscopy characterization data provided evidence that the transfer pathway of space charge in the CO2 reduction process was in accordance with the S-scheme. This research provides a simple strategy through which one can optimize the band structure to promote the separation of photogenerated carriers and achieve a high efficiency of CO2 reduction.

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Boosting the catalytic activity of a step-scheme In2O3/ZnIn2S4 hybrid system for the photofixation of nitrogen Jin Zhang, Zi-Hao Pan, Ying Yang, Peng-Fei Wang, Chen-Yang Pei, Wei Chen, Guo-Bo Huang 2022, 43 (2):  265-275.  DOI: 10.1016/S1872-2067(21)63801-9 Abstract ( 134 )   HTML ( 14 )   PDF (1535KB) ( 172 )   Supporting Information In this study, a step-scheme photocatalytic system comprising one-dimensional In2O3 nanorods and two-dimensional ZnIn2S4 nanosheets was developed for the catalytic photofixation of nitrogen. The effects of the combination of In2O3 with ZnIn2S4 on the crystallinity, microstructure, optical absorption, and charge transfer behavior of the In2O3/ZnIn2S4 hybrid photocatalysts were investigated. Benefiting from the synergistic effects of the photogenerated vacancies and a step-scheme charge separation mechanism, the In2O3/ZnIn2S4 hybrid photocatalyst exhibited significantly enhanced catalytic activity compared to those of bare In2O3 and pure ZnIn2S4, and an optimized 50 wt% In2O3/ZnIn2S4 hybrid sample was found to exhibit superior catalytic activity for the photofixation of N2, fixing 18.1 ±0.77 mg·L -1 of ammonia after exposure to simulated sunlight for 2 h. Crucially, the results of trapping experiments and electron paramagnetic resonance investigation to identify the active species confirmed that the catalytic nitrogen photofixation performance was highly correlated with the presence of ·CO2 -radicals rather than photogenerated electrons, especially when methanol was used as a hole scavenger. In summary, the reported In2O3/ZnIn2S4 hybrid photocatalysts exhibit both stability and high activity for the photofixation of N2, making them promising catalysts for sunlight-driven artificial N2 fixation.

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Promoting photocarriers separation in S-scheme system with Ni2P electron bridge: The case study of BiOBr/Ni2P/g-C3N4 Nannan Chen, Xuemei Jia, Heng He, Haili Lin, Minna Guo, Jing Cao, Jinfeng Zhang, Shifu Chen 2022, 43 (2):  276-287.  DOI: 10.1016/S1872-2067(21)63817-2 Abstract ( 88 )   HTML ( 4 )   PDF (1916KB) ( 143 )   Supporting Information Constructing step-scheme (S-scheme) heterojunctions can considerably facilitate separation and transfer of photocarriers, as well as promote strong redox ability. The interface resistance of heterojunctions immediately affects photocarrier separation and determines the photocatalytic activity. Herein, we constructed a novel BiOBr/Ni2P/g-C3N4 heterojunction using Ni2P as a novel electron bridge to reduce the interfacial resistance of photocarriers between BiOBr and g-C3N4. The as-prepared 10% BiOBr/Ni2P/g-C3N4 sample exhibited outstanding visible-light photocatalytic performance for methyl orange and rhodamine B removal, with degradation efficiencies of 91.4% and 98.9%, respectively. The excellent photocatalytic activity of BiOBr/Ni2P/g-C3N4 was mainly attributed to the synergistic effects of the Ni2P cocatalyst and S-scheme heterojunction, which not only reduced the interface resistance but also retained the strong redox potential of the photocarriers. In addition, the formation of the S-scheme system was supported by active oxygen species investigation, current-voltage curves, and density functional theory calculations. This work provides a guideline for the design of highly efficient S-scheme photocatalysts with transition metal phosphates as electron bridges to improve photocarriers separation.

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Rod-like Bi4O5I2/Bi4O5Br2 step-scheme heterostructure with oxygen vacancies synthesized by calcining the solid solution containing organic group Xuemei Jia, Zichen Shen, Qiaofeng Han, Huiping Bi 2022, 43 (2):  288-302.  DOI: 10.1016/S1872-2067(20)63768-8 Abstract ( 138 )   HTML ( 3 )   PDF (3015KB) ( 130 )   Supporting Information To improve separation efficiency of the photogenerated electron-hole pairs, constructing a heterojunction is considered to be a promising strategy. However, the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging. In this work, a well-designed nanosheet-based rodlike step-scheme (S-scheme) heterojunction Bi4O5I2/Bi4O5Br2 with rich oxygen vacancies (OVs) (Bi4O5I2/Bi4O5Br2-OV) was easily synthesized by calcining BiOAc0.6Br0.2I0.2 (Ac - = CH3COO -) precursor. The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline (TC) and dye rhodamine B (RhB) degradation and removal rate reached 90.2% and 97.0% within 120 min, respectively, which was higher than those of Bi4O5I2-OV (56.8% and 71.8%), Bi4O5Br2-OV (47.4% and 68.4%), solid solution BiOAc0.6Br0.2I0.2 (67.0% and 84.0%) and Bi4O5I2/Bi4O5Br2 with poor oxygen vacancies (Bi4O5I2/Bi4O5Br2-P) (30.6% and 40.4%). Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac -, it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides, which thus decreased particle size and increased surface areas, but also introduce surface OVs, which could trap photoelectrons and inhibit the recombination of carriers. In addition, the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials, which facilitates charge carriers transfer at the interfaces. The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and RhB in actual wastewater or in the presence of some electrolytes. This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.

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Efficient photocatalytic hydrogen evolution over graphdiyne boosted with a cobalt sulfide formed S-scheme heterojunction Zhiliang Jin, Hongying Li, Junke Li 2022, 43 (2):  303-315.  DOI: 10.1016/S1872-2067(21)63818-4 Abstract ( 170 )   HTML ( 5 )   PDF (2992KB) ( 233 )   Graphdiyne (GDY, g-CnH2n-2), a novel two-dimensional carbon hybrid material, has attracted significant attention owing to its unique and excellent properties. As a new type of carbon material, GDY has a layered structure and can be used in the field of photocatalytic water splitting. Therefore, herein, new progress in the preparation of graphene using CuI powder as a catalytic material and the combination of a facile hydrothermal method to prepare a new composite material, Co9S8-GDY-CuI, is reported. The hydrogen production activity of Co9S8-GDY-CuI in the sensitization system reached 1411.82 μmol g -1 h -1, which is 10.29 times that of pure GDY. A series of characterization techniques were used to provide evidence for the successful preparation of the material and its superior photocatalytic activity. Raman spectroscopy showed that the material contains acetylenic bonds, and the X-ray photoelectron spectroscopy carbon fitting peaks indicated the presence of C-C(sp 2) and C-C(sp), further demonstrating that GDY was successfully prepared. A possible reaction mechanism was proposed by making use of UV-visible diffuse reflectance and Mott-Schottky analyses. The results showed that a double S-scheme heterojunction was constructed between the samples, which effectively accelerated the separation and transfer of electrons. In addition, the introduction of Co9S8 nanoparticles greatly improved the visible light absorption capacity of Co9S8-GDY-CuI. Photoluminescence spectroscopy and related electrochemical characterization further proved that recombination of the electron-hole pairs in the composite material was effectively suppressed.

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In-situ pressure-induced BiVO4/Bi0.6Y0.4VO4 S-scheme heterojunction for enhanced photocatalytic overall water splitting activity Weiqi Guo, Haolin Luo, Zhi Jiang, Wenfeng Shangguan 2022, 43 (2):  316-328.  DOI: 10.1016/S1872-2067(21)63846-9 Abstract ( 146 )   HTML ( 5 )   PDF (2625KB) ( 572 )   Supporting Information Step-scheme (S-scheme) heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation. The latter is critical in controlling the overall efficiency in one-step photoexcitation systems. In this study, a nanosized Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes. The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase, which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of Bi0.6Y0.4VO4. Bi0.6Y0.4VO4 with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare Bi0.6Y0.4VO4. Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting (OWS) activity. Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction. This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination. This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition. The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.

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Step-scheme ZnO@ZnS hollow microspheres for improved photocatalytic H2 production performance Jie Jiang, Guohong Wang, Yanchi Shao, Juan Wang, Shuang Zhou, Yaorong Su 2022, 43 (2):  329-338.  DOI: 10.1016/S1872-2067(21)63889-5 Abstract ( 330 )   HTML ( 14 )   PDF (3025KB) ( 246 )   Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance. In this study, we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy. The ZnO@ZnS step-scheme photocatalysts had a large surface area, high light utilization capacity, and superior separation efficiency for photogenerated charge carriers. In addition, the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field. Our study paves the way for design of high-performance photocatalysts for H2 production.

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1D/2D TiO2/ZnIn2S4 S-scheme heterojunction photocatalyst for efficient hydrogen evolution Jinmao Li, Congcong Wu, Jin Li, Binghai Dong, Li Zhao, Shimin Wang 2022, 43 (2):  339-349.  DOI: 10.1016/S1872-2067(21)63875-5 Abstract ( 186 )   HTML ( 5 )   PDF (1875KB) ( 264 )   TiO2 is a promising photocatalyst with limited use in practical applications owing to its wide bandgap, narrow light response range, and rapid recombination of photoexcited carriers. To address these limitations, a novel 1D/2D TiO2/ZnIn2S4 heterostructure was designed according to the principles of the S-scheme heterojunction. The TiO2/ZnIn2S4 (TZISx) hybrids prepared via a hydrothermal method afforded significant improvement in photocatalytic hydrogen evolution (PHE) in comparison to pristine TiO2 and ZnIn2S4. In particular, the optimal TZIS2 sample (mass ratio of ZnIn2S4 to TiO2 was 0.4) exhibited the highest PHE activity (6.03 mmol/h/g), which was approximately 3.7 and 2.0 times higher than those of pristine TiO2 and ZnIn2S4, respectively. This improvement in the PHE of the TZIS2 sample could be attributed to the formation of an intimate heterojunction interface, high-efficiency separation of charge carriers, abundant reactive sites, and enhanced light absorption capacity. Notably, theoretical and experimental results demonstrated that the S-scheme mechanism of interfacial electron transfer in the TZISx composites facilitated the transfer and separation of photoexcited charge carriers, resulting in more isolated photoexcited electrons for the PHE reaction.

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Fabricating covalent organic framework/CdS S-scheme heterojunctions for improved solar hydrogen generation Long Sun, Lingling Li, Juan Yang, Jiajie Fan, Quanlong Xu 2022, 43 (2):  350-358.  DOI: 10.1016/S1872-2067(21)63869-X Abstract ( 341 )   HTML ( 12 )   PDF (3681KB) ( 314 )   The fabrication of S-scheme heterojunctions has received considerable attention as an effective approach to promote the separation and migration of photoexcited electron/hole pairs and retain strong redox abilities. Herein, an imine-based porous covalent organic framework (COF-LZU1) is integrated with controllably fabricated CdS hollow cubes, resulting in the formation of an S-scheme heterojunction. When the COF content reaches 1.5 wt%, the COF/CdS heterostructure (1.5%COF/CdS) achieves the highest hydrogen generation rate of 8670 μmol·h -1·g -1, which is approximately 2.1 times higher than that of pure CdS. The apparent quantum efficiency (AQE) of 1.5%COF/CdS is approximately 8.9% at 420 nm. Further systematic analysis shows that the intimate contact interface and suitable energy band structures between CdS and COF can induce the formation of an internal electric field at the heterojunction interface, which can effectively drive the spatial separation of photoexcited charge carriers and simultaneously maintain a strong redox ability, thus enhancing the photocatalytic H2 evolution performance.

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Integration of 2D layered CdS/WO3 S-scheme heterojunctions and metallic Ti3C2 MXene-based Ohmic junctions for effective photocatalytic H2 generation Junxian Bai, Rongchen Shen, Zhimin Jiang, Peng Zhang, Youji Li, Xin Li 2022, 43 (2):  359-369.  DOI: 10.1016/S1872-2067(21)63883-4 Abstract ( 286 )   HTML ( 8 )   PDF (3917KB) ( 316 )   Supporting Information The rapid recombination of photo-generated electron-hole pairs, insufficient active sites, and strong photocorrosion have considerably restricted the practical application of CdS in photocatalytic fields. Herein, we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces. Experiments using electron spin resonance spectroscopy, ultraviolet photoelectron spectroscopy, and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO3 step-scheme (S-scheme) heterojunctions and CdS/MX ohmic junctions. Impressively, it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO3 nanosheets. In addition, 2D Ti3C2 MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with CdS nanosheets, thus providing a greater number of electron transfer pathways and hydrogen evolution sites. Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-CdS/WO3 layered multi-heterostructures could reach as high as 27.5 mmol/g/h, which was 11.0 times higher than that of pure CdS nanosheets. Notably, the apparent quantum efficiency reached 12.0% at 450 nm. It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.

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In situ fabrication of Bi2Se3/g-C3N4 S-scheme photocatalyst with improved photocatalytic activity Rongan He, Sijiao Ou, Yexuan Liu, Yu Liu, Difa Xu 2022, 43 (2):  370-378.  DOI: 10.1016/S1872-2067(21)63911-6 Abstract ( 193 )   HTML ( 8 )   PDF (1060KB) ( 365 )   Supporting Information Bismuth selenide (Bi2Se3) is an attractive visible-light-responsive semiconductor that can absorb a full range of visible and near-infrared light. However, its poor redox capacity and rapid carrier recombination limit its application in photocatalytic oxidation. In this study, we adopted Bi2Se3 as the couple part of graphitic carbon nitride (g-C3N4) to construct a Bi2Se3/g-C3N4 composite photocatalyst. Through in situ fabrication, the self-developed Bi2O3/g-C3N4 precursor was transformed into a Bi2Se3/g-C3N4 heterojunction. The as-prepared Bi2Se3/g-C3N4 composite exhibited much higher visible-light-driven photocatalytic activity than pristine Bi2Se3 and g-C3N4 in the removal of phenol. The enhanced photocatalytic activity was ascribed to the S-scheme configuration of Bi2Se3/g-C3N4; this was confirmed by the energy-level shift, photoluminescence analysis, computational structure study, and reactive-radical testing. In the S-scheme heterojunction, photo-excited electrons in the conduction band of g-C3N4 migrate to the valence band of Bi2Se3 and combine with the excited holes therein. By consuming less reactive carriers, the S-scheme heterojunction can not only effectively promote charge separation, but also preserve more reactive photo-generated carriers. This property enhances the photocatalytic activity.

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Highly efficient UV-visible-infrared photothermocatalytic removal of ethyl acetate over a nanocomposite of CeO2 and Ce-doped manganese oxide Long Zhang, Yi Yang, Yuanzhi Li, Jichun Wu, Shaowen Wu, Xin Tan, Qianqian Hu 2022, 43 (2):  379-390.  DOI: 10.1016/S1872-2067(21)63816-0 Abstract ( 192 )   HTML ( 7 )   PDF (1745KB) ( 143 )   Supporting Information A unique nanocomposite of CeO2 nanoparticles and Ce-doped manganese oxide nanofibers having a crystalline cryptomelane-type octahedral molecular sieve (KMn8O16·nH2O, abbreviated as OMS-2) structure (denoted CeO2-CeOMS-2) was prepared by the reaction of Ce(NO3)3 and KMnO4 at 90 °C. CeO2-CeOMS-2 shows extremely high photothermocatalytic activity, very low selectivity for acetaldehyde (an unfavorable byproduct), and excellent durability for ethyl acetate removal under UV-visible-infrared (UV-vis-IR) irradiation. In striking contrast, pure CeO2, pure OMS-2, and TiO2 (P25) showed much lower photothermocatalytic activities and higher selectivities for acetaldehyde. The CO2 production rate within the first five minutes (rCO2) of reaction with CeO2-CeOMS-2 was as high as 1102.5 μmol g -1 min -1, which is 137, 17, and 30-times higher than those of pure CeO2, pure OMS-2, and TiO2 (P25), respectively. CeO2-CeOMS-2 also shows good photothermocatalytic activity under vis-IR (λ > 420 or 560 nm) irradiation. Further, even under vis-IR (λ > 830 nm) irradiation, efficient photothermocatalytic activity was achieved. In addition, the catalytic activity of CeO2-CeOMS-2 is far superior to those of pure CeO2 and OMS-2, which is attributed to the fact that Ce doping significantly improves the lattice oxygen activity of OMS-2. The high photothermocatalytic activity of CeO2-CeOMS-2 arises from the synergy between the photocatalytic effect of the CeO2 nanoparticles and light-driven thermocatalysis of the Ce-doped OMS-2. The novel photoactivation of Ce-doped OMS-2, which is unlike that of conventional photocatalysis on semiconductor photocatalysts, further promotes the catalytic activity because the surface oxygen activity of Ce-doped OMS-2 is promoted upon UV-vis-IR or vis-IR (λ > 560 nm) irradiation.

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Photo-enhanced thermal catalytic CO2 methanation activity and stability over oxygen-deficient Ru/TiO2 with exposed TiO2 {001} facets: Adjusting photogenerated electron behaviors by metal-support interactions Ke Wang, Shihui He, Yunzhi Lin, Xun Chen, Wenxin Dai, Xianzhi Fu 2022, 43 (2):  391-402.  DOI: 10.1016/S1872-2067(21)63825-1 Abstract ( 238 )   HTML ( 8 )   PDF (3263KB) ( 177 )   Supporting Information In this study, two Ru/TiO2 samples with different TiO2 facets were prepared to investigate their photo-thermal catalytic CO2 + H2 reaction behavior. Without UV irradiation, the Ru/TiO2 with 67% {001} facet (3RT) displayed improved thermal catalytic activity for CO2 methanation than that of Ru/TiO2 with 30% {001} facet (0RT). After H2 pretreatment, both samples exhibited enhanced thermal catalytic activities, but the H2-treated 3RT (3RT-H) exhibited superior activity to that of the H2-treated 0RT (0RT-H). Under UV irradiation, 3RT-H exhibited apparent photo-promoted thermal catalytic activity and stability, but the enhanced catalytic activity was lower than that of 0RT-H. Based on the characterization results, it is proposed that both the surface oxygen vacancies (Vos) (activating CO2) and the metallic Ru nanoparticles (activating H2) were mainly responsible for CO2 methanation. For 0RT, H2 pretreatment and subsequent UV irradiation did not promote the formation of Vos, resulting in low catalytic activity. For 3RT, on the one hand, H2 pretreatment promoted the formation of Vos, which were regenerated under UV irradiation; on the other hand, the photogenerated electrons from TiO2 transferred to Ru to maintain the metallic Ru nanoparticles. Both behaviors promoted the activation of CO2 and H2 and enhanced CO2 methanation. Moreover, the photogenerated holes favored the dissociated H at Ru migrating to TiO2, also promoting CO2 methanation. These behaviors occurring on 3RT-H may be attributed to the suitable metal-support interaction between the Ru nanoparticles and TiO2 {001}, resulting in the easy activation of lattice oxygen in TiO2 to Vos. With reference to the analysis of intermediates, a photo-thermal reaction mechanism is proposed for the Ru/TiO2 {001} facet sample.

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Ultrahigh photocatalytic hydrogen evolution performance of coupled 1D CdS/1T-phase dominated 2D WS2 nanoheterojunctions Chao Ding, Chengxiao Zhao, Shi Cheng, Xiaofei Yang 2022, 43 (2):  403-409.  DOI: 10.1016/S1872-2067(21)63844-5 Abstract ( 168 )   HTML ( 2 )   PDF (2223KB) ( 118 )   Supporting Information Solar-powered photocatalytic hydrogen production from water using semiconductors provides an eco-friendly and promising approach for converting solar energy into hydrogen fuel. Bulk semiconductors generally suffer from certain limitations, such as poor visible-light utilization, rapid recombination of charge carriers, and low catalytic capability. The key challenge is to develop visible-light-driven heterojunction photocatalysts that are stable and highly active during the water splitting process. Here, we demonstrate the integration of one-dimensional (1D) CdS nanorods with two-dimensional (2D) 1T-phase dominated WS2 nanosheets for constructing mixed-dimensional heterojunctions for the photocatalytic hydrogen evolution reaction (HER). The resulting 1D CdS/2D WS2 nanoheterojunction exhibited an ultrahigh hydrogen-evolution activity of ~70 mmol•g -1•h -1 that was visible to the naked eye, as well as long-term stability under visible light illumination. The results reveal that the synergy of hybrid nanoarchitectures and intimate interfacial contact between the 1D CdS nanorods and 1T-phase dominated 2D WS2 nanosheets facilitates charge carrier transport, which is beneficial for achieving superior hydrogen evolution.

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Comprehensive investigation on robust photocatalytic hydrogen production over C3N5 Cong Peng, Lixiao Han, Jinming Huang, Shengyao Wang, Xiaohu Zhang, Hao Chen 2022, 43 (2):  410-420.  DOI: 10.1016/S1872-2067(21)63813-5 Abstract ( 310 )   HTML ( 7 )   PDF (2533KB) ( 262 )   Carbon nitride has drawn numerous eyes in the past decade, whereas the photocatalytic performance is significantly limited by its wide band-gap (~2.7 eV for C3N4) simultaneously. Recently, C3N5 with narrower band-gap has been reported, however, a systematically investigation on its photoactivity for H2 production has not been reported. The present work demonstrates the synthesis of C3N5 by thermal treatment of 3-amino-1,2,4-triazole, and the photocatalytic performance for H2 production of C3N5 is investigated comprehensively. Photocatalytic H2 production rate of C3N5 is ~2.2 times higher than that of C3N4 with 1.0 wt% Pt as co-catalyst, and series of experiments are carried out to explore the behind elements accounting for the high photoactivity. Combining the results of DRS, PL and photocurrent, it is found that C3N5 possesses wider visible light absorption region, lower band-gap and quicker photogenerated e -/h + separation efficiency. Moreover, characterizations including in-situ DRIFTS are adopted to monitor the adsorption property of H2O on C3N5, which plays a significant role in surface water reduction reaction, and higher amount of adsorbed H2O molecules on C3N5 is confirmed. The present work exhibits new insights into the high photocatalytic performance of N-rich carbon nitride catalysts.

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Doping-induced metal-N active sites and bandgap engineering in graphitic carbon nitride for enhancing photocatalytic H2 evolution performance Xiaohui Yu, Haiwei Su, Jianping Zou, Qinqin Liu, Lele Wang, Hua Tang 2022, 43 (2):  421-432.  DOI: 10.1016/S1872-2067(21)63849-4 Abstract ( 364 )   HTML ( 10 )   PDF (6890KB) ( 207 )   Supporting Information Durable and inexpensive graphitic carbon nitride (g-C3N4) demonstrates great potential for achieving efficient photocatalytic hydrogen evolution reduction (HER). To further improve its activity, g-C3N4 was subjected to atomic-level structural engineering by doping with transition metals (M = Fe, Co, or Ni), which simultaneously induced the formation of metal-N active sites in the g-C3N4 framework and modulated the bandgap of g-C3N4. Experiments and density functional theory calculations further verified that the as-formed metal-N bonds in M-doped g-C3N4 acted as an “electron transfer bridge”, where the migration of photo-generated electrons along the bridge enhanced the efficiency of separation of the photogenerated charges, and the optimized bandgap of g-C3N4 afforded stronger reduction ability and wider light absorption. As a result, doping with either Fe, Co, or Ni had a positive effect on the HER activity, where Co-doped g-C3N4 exhibited the highest performance. The findings illustrate that this atomic-level structural engineering could efficiently improve the HER activity and inspire the design of powerful photocatalysts.

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Enhanced photoelectrochemical water splitting using a cobalt-sulfide-decorated BiVO4 photoanode Zhiming Zhou, Jinjin Chen, Qinlong Wang, Xingxing Jiang, Yan Shen 2022, 43 (2):  433-441.  DOI: 10.1016/S1872-2067(21)63845-7 Abstract ( 136 )   HTML ( 6 )   PDF (1595KB) ( 212 )   Supporting Information Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental issues. Bismuth vanadate (BiVO4) is photoanode material with tremendous potential for photoelectrochemical (PEC) water splitting. However, its PEC performance is severely hindered owing to poor surface charge transfer, surface recombination at the photoanode/electrolyte junction, and sluggish oxygen evolution reaction (OER) kinetics. In this regard, a novel solution was developed in this study to address these issues by decorating the surface of BiVO4 with cobalt sulfide, whose attractive features such as low cost, high conductivity, and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO4 photoanode. The fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 mA cm -2 under illumination at 1.23 V vs. a reversible hydrogen electrode, which is more than 2.5 times greater than that of pristine BiVO4. Moreover, the CoS/BiVO4 photoanode also exhibited considerable improvements in the charge injection yield (75.8% vs. 36.7% for the bare BiVO4 film) and charge separation efficiency (79.8% vs. 66.8% for the pristine BiVO4 film). These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO4 by CoS. This study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.

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Wheel-shaped icosanuclear Cu-containing polyoxometalate catalyst: Mechanistic and stability studies on light-driven hydrogen generation Yeqin Feng, Lin Qin, Junhao Zhang, Fangyu Fu, Huijie Li, Hua Xiang, Hongjin Lv 2022, 43 (2):  442-450.  DOI: 10.1016/S1872-2067(21)63840-8 Abstract ( 137 )   HTML ( 4 )   PDF (1718KB) ( 150 )   Supporting Information In this paper, we report the synthesis and characterization of a wheel-shaped icosanuclear Cu-containing polyoxometalate (POM), K12Li13[Cu20Cl(OH)24(H2O)12(P8W48O184)]·22H2O (K12Li13-Cu20P8W48). The resulting cation-exchanged tetrabutylammonium salt of the polyoxoanion Cu20P8W48 (TBA-Cu20P8W48) exhibits high efficiency for visible-light-driven H2 production in the presence of an [Ir(ppy)2(dtbbpy)][PF6] photosensitizer and a triethanolamine electron donor. Under optimal conditions, the turnover number for H2 production reaches ~2892 after 5 h of photocatalysis and thereafter continuously increases to ~13400 in a long-term 120 h reaction, representing the best performance among all reported transition-metal-substituted POM catalysts. Mechanistic studies confirm the existence of reductive and oxidative quenching processes, of which the reductive quenching pathway is dominant. Various stability tests demonstrate that the TBA-Cu20P8W48 catalyst slowly dissociates Cu ions under turnover conditions; however, both the starting TBA-Cu20P8W48 and its molecular decomposition products are dominant active species for efficient and long-term H2 production.

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Copper and platinum dual-single-atoms supported on crystalline graphitic carbon nitride for enhanced photocatalytic CO2 reduction Lei Cheng, Peng Zhang, Qiye Wen, Jiajie Fan, Quanjun Xiang 2022, 43 (2):  451-460.  DOI: 10.1016/S1872-2067(21)63879-2 Abstract ( 390 )   HTML ( 19 )   PDF (2238KB) ( 354 )   Supporting Information Single-atom Pt catalysts are designed to promote efficient atom utilization, whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing. Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability. In this study, we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO2 reduction. N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers. The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride (PtCu-crCN) exhibited high selectivity and activity for CO2 conversion without the addition of any cocatalyst or sacrificial agent. In particular, we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH4 generation. The mechanism of CO2 photoreduction for PtCu-crCN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images, in situ irradiated X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.

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Ti3C2 MXene co-catalyst assembled with mesoporous TiO2 for boosting photocatalytic activity of methyl orange degradation and hydrogen production Huapeng Li, Bin Sun, Tingting Gao, Huan Li, Yongqiang Ren, Guowei Zhou 2022, 43 (2):  461-471.  DOI: 10.1016/S1872-2067(21)63915-3 Abstract ( 321 )   HTML ( 6 )   PDF (1885KB) ( 277 )   Supporting Information Photocatalytic degradation and hydrogen production using solar energy through semiconductor photocatalysts are deemed to be a powerful approach for solving environmental and energy crisis. However, the biggest challenge in photocatalysis is the efficient separation of photo-induced carriers. To this end, we report that the mesoporous TiO2 nanoparticles are anchored on highly conductive Ti3C2 MXene co-catalyst by electrostatic self-assembly strategy. The constructed mesoporous TiO2/Ti3C2 composites display that the mesoporous TiO2 nanoparticles are uniformly distributed on the surface of layer structured Ti3C2 nanosheets. More importantly, the as-obtained mesoporous TiO2/Ti3C2 composites reveal the significantly enhanced light absorption performance, photo-induced carriers separation and transfer ability, thus boosting the photocatalytic activity. The photocatalytic methyl orange degradation efficiency of mesoporous TiO2/Ti3C2 composite with an optimized Ti3C2 content (3 wt%) can reach 99.6% within 40 min. The capture experiments of active species confirm that the ·O2 - and ·OH play major role in photocatalytic degradation process. Furthermore, the optimized mesoporous TiO2/Ti3C2 composite also shows an excellent photocatalytic H2 production rate of 218.85 μmol g -1 h -1, resulting in a 5.6 times activity as compared with the pristine mesoporous TiO2 nanoparticles. This study demonstrates that the MXene family materials can be applied as highly efficient noble-metal-free co-catalysts in the field of photocatalysis.

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Solvothermal fabrication of Bi2MoO6 nanocrystals with tunable oxygen vacancies and excellent photocatalytic oxidation performance in quinoline production and antibiotics degradation Zhen Liu, Jian Tian, Changlin Yu, Qizhe Fan, Xingqiang Liu 2022, 43 (2):  472-484.  DOI: 10.1016/S1872-2067(21)63876-7 Abstract ( 265 )   HTML ( 14 )   PDF (2535KB) ( 306 )   Supporting Information Novel Bi2MoO6 nanocrystals with tunable oxygen vacancies have been developed via a facile low-cost approach with the assistance of a glyoxal reductant under solvothermal conditions. With the introduction of oxygen vacancies, the optical absorption of Bi2MoO6 is extended and its bandgap narrowed. Oxygen vacancies not only lead to the appearance of a defect band level in the forbidden band but can also result in a minor up-shift of the valence band maximum, promoting the mobility of photogenerated holes. Moreover, oxygen vacancies can act as electron acceptors, temporarily capturing electrons excited by light and reducing the recombination of electrons and holes. At the same time, oxygen vacancies help to capture oxygen, which reacts with the captured photogenerated electrons to generate more superoxide radicals (•O2 -) to participate in the reaction, thereby significantly promoting the redox performance of the photocatalyst. From Bi2MoO6 containing these oxygen vacancies (OVBMO), excellent photocatalytic performance has been obtained for the oxidation of 1,2,3,4-tetrahydroquinoline to produce quinoline and cause antibiotic degradation. The reaction mechanism of the oxidation of 1,2,3,4-tetrahydroquinoline to quinoline over the OVBMO materials is elucidated in terms of heterogeneous Catal. via a radical pathway.

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Enhancing an internal electric field by a solid solution strategy for steering bulk-charge flow and boosting photocatalytic activity of Bi24O31ClxBr10-x Jun Wan, Weijie Yang, Jiaqing Liu, Kailong Sun, Lin Liu, Feng Fu 2022, 43 (2):  485-496.  DOI: 10.1016/S1872-2067(21)63897-4 Abstract ( 97 )   HTML ( 2 )   PDF (8280KB) ( 93 )   Supporting Information Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community; however, a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear. Herein, a series of Bi24O31ClxBr10-x solid solutions with the same structural characteristics were synthesized by crystal structure regulation. Combining density functional theory calculation, Kelvin probe force microscopy, and zeta potential testing results, an enhanced internal electric field (IEF) intensity between [Bi24O31] and [X] layers was achieved by changing halogen types and ratios. This greatly facilitated bulk-charge separation and transfer efficiency, which is significant for the degradation of phenolic organic pollutants. Owing to the enhanced IEF intensity, the charge carrier density of Bi24O31Cl4Br6 was 33.1 and 4.7 times stronger than that of Bi24O31Cl10 and Bi24O31Br10, respectively. Therefore, Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A, which was 6.21 and 2.71 times higher than those of Bi24O31Cl10 and Bi24O31Br10, respectively. Thus, this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.

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Precursor-modified strategy to synthesize thin porous amino-rich graphitic carbon nitride with enhanced photocatalytic degradation of RhB and hydrogen evolution performances Ting Huang, Jiaqi Chen, Lili Zhang, Alireza Khataee, Qiaofeng Han, Xiaoheng Liu, Jingwen Sun, Junwu Zhu, Shugang Pan, Xin Wang, Yongsheng Fu 2022, 43 (2):  497-506.  DOI: 10.1016/S1872-2067(21)63873-1 Abstract ( 169 )   HTML ( 8 )   PDF (3278KB) ( 168 )   Supporting Information The photocatalytic activity of carbon nitride (CN) materials is mainly limited to small specific surface areas, limited solar absorption, and low separation and mobility of photoinduced carriers. In this study, we developed a precursor-modified strategy for the synthesis of graphitic CN with highly efficient photocatalytic performance. The precursor dicyandiamide reformed by different acids undergoes a basic structural change and transforms into diverse new precursors. The thin porous amino-rich HNO3-CN (5H-CN) was calcined by dicyandiamidine nitrate, formed by concentrated nitric acid modified dicyandiamide, and presented the best photocatalytic degradation rate of RhB, more than 34 times that of bulk graphitic CN. Moreover, the photocatalytic hydrogen evolution rate of 5H-CN significantly improved. The TG-DSC-FTIR analyses indicated that the distinguishing thermal polymerization process of 5H-CN led to its thin porous amino-rich structure, and the theoretical calculations revealed that the negative conduction band potential of 5H-CN was attributed to its amino-rich structure. It is anticipated that the thin porous structure and the negative conduction band position of 5H-CN play important roles in the improvement of the photocatalytic performance. This study demonstrates that precursor modification is a promising project to induce a new thermal polycondensation process for the synthesis of CN with enhanced photocatalytic performance.

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Tracking charge transfer pathways in SrTiO3/CoP/Mo2C nanofibers for enhanced photocatalytic solar fuel production Li Wang, Yukun Li, Chao Wu, Xin Li, Guosheng Shao, Peng Zhang 2022, 43 (2):  507-518.  DOI: 10.1016/S1872-2067(21)63898-6 Abstract ( 166 )   HTML ( 10 )   PDF (12193KB) ( 287 )   Supporting Information Photocatalytic solar fuel generation is currently a hot topic because of its potential for solving the energy crisis owing to its low cost and zero-carbon emissions. However, the rapid bulk recombination of photoexcited carrier pairs is a fundamental disadvantage. To resolve this problem, we synthesized a dual cocatalysts system of cobalt phosphide (CoP) and molybdenum carbide (Mo2C) embedded on strontium titanate (SrTiO3) nanofibers. Compared with those of pristine SrTiO3 and binary samples, the dual cocatalysts system (denoted SCM) showed a significant improvement in the hydrogen evolution and CO2 reduction performance. Further, the structure of SCM effectively promoted spatial charge separation and enhanced the photocatalytic performance. In addition, the Schottky junction formed between the SrTiO3 and cocatalysts enabled the rapid transfer of photoexcited electrons from SrTiO3 to the cocatalysts, resulting in effective separation and prolonged photoexcited electron lifetimes. The electron migration route between SrTiO3 and the cocatalysts was determined by in situ irradiation X-ray spectroscopy, and band structures of SrTiO3 and the cocatalysts are proposed based on results obtained from UV-vis diffraction reflection spectroscopy and ultraviolet photoelectron spectroscopy measurements. On the basis of our results, the dual cocatalysts unambiguously boosts charge separation and enhances photocatalytic performance. In summary, we have investigated the flux of photoexcited electrons in a dual cocatalysts system and provided a theoretical basis and ideas for subsequent research.

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Electric-field promoted C-C coupling over Cu nanoneedles for CO2 electroreduction to C2 products HuangJingWei Li, Huimin Zhou, Yajiao Zhou, Junhua Hu, Masahiro Miyauchi, Junwei Fu, Min Liu 2022, 43 (2):  519-525.  DOI: 10.1016/S1872-2067(21)63866-4 Abstract ( 266 )   HTML ( 9 )   PDF (3404KB) ( 174 )   Supporting Information Cu-based catalysts are the most promising candidates for electrochemical CO2 reduction (CO2RR) to multi-carbon (C2) products. Optimizing the C-C coupling process, the rate-determining step for C2 product generation, is an important strategy to improve the production and selectivity of the C2 products. In this study, we determined that the local electric field can promote the C-C coupling reaction and enhance CO2 electroreduction to C2 products. First, finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips. Density functional theory (DFT) calculations proved that a large electric field can promote C-C coupling. Motivated by this prediction, we prepared a series of Cu catalysts with different curvatures. The Cu nanoneedles (NNs) exhibited the largest number of curvatures, followed by the Cu nanorods (NRs), and Cu nanoparticles (NPs). The Cu NNs contained the highest concentration of adsorbed K +, which resulted in the highest local electric field on the needles. CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability, and in-situ Fourier-transform infrared spectroscopy (FTIR) showed the strongest *COCO and *CO signals for the Cu NNs. These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field, thus promoting C-C coupling. As a result, the Cu NNs show a maximum FEC2 of 44% for CO2RR at a low potential (-0.6 V vs. RHE), which is approximately 2.2 times that of the Cu NPs. This work provides an effective strategy for enhancing the production of multi-carbon products during CO2RR.

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Negative inductive effect enhances charge transfer driving in sulfonic acid functionalized graphitic carbon nitride with efficient visible-light photocatalytic performance Min Zhang, Yunfeng Li, Wei Chang, Wei Zhu, Luohong Zhang, Renxi Jin, Yan Xing 2022, 43 (2):  526-535.  DOI: 10.1016/S1872-2067(21)63872-X Abstract ( 196 )   HTML ( 12 )   PDF (2118KB) ( 150 )   Supporting Information Efficient photogenerated carrier migration/separation plays a critical role in increasing the photocatalytic performance of g-C3N4. Herein, sulfonic acid group-functionalized g-C3N4 (SACN) was synthesized and then synchronously strengthened by a facile-solid-state thermal reaction of g-C3N4 and sulfamic acid. As a solid strong acid, sulfamic acid can be used to achieve acid etching on the surface of g-C3N4 with the assistance of thermal treatment, leading to an enlarged specific surface area and increased surface catalytic reaction sites. More importantly, our experiments and density functional theory calculations indicate that the driving force generated by the negative inductive effect of sulfonic acid groups significantly improves the charge transfer dynamics and effectively inhibits their recombination. Moreover, the negative inductive effect can induce charge redistribution, which reduces the conduction band potential of g-C3N4 to enhance the reduction ability of photo-induced electrons. As a result, the SACN-400 sample showed excellent photocatalytic performance in H2 generation with an apparent quantum efficiency of 11.03% at 420 ± 15 nm, as well as an efficient photodegradation rate for organic pollutants.

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Monodisperse Ni-clusters anchored on carbon nitride for efficient photocatalytic hydrogen evolution Liang Jian, Huizhen Zhang, Bing Liu, Chengsi Pan, Yuming Dong, Guangli Wang, Jun Zhong, Yongjie Zheng, Yongfa Zhu 2022, 43 (2):  536-545.  DOI: 10.1016/S1872-2067(21)63865-2 Abstract ( 210 )   HTML ( 8 )   PDF (3456KB) ( 178 )   Supporting Information The active sites of monodisperse transition metal Ni-clusters were anchored on carbon nitride (CN) by an in situ photoreduction deposition method to promote the efficient separation of photogenerated charges and achieve high-efficiency photocatalytic activity for hydrogen evolution. The Ni-cluster/CN exhibited a photocatalytic hydrogen production rate of 16.5 mmol·h -1·g -1 and a total turnover frequency (TOF (H2)) value of 461.14 h -1. X-ray absorption spectroscopy based on synchrotron radiation indicated that CN had two reaction centers to form stable interface interactions with monodispersed Ni-clusters, in which carbon can act as an electron acceptor, while nitrogen can act as an electron donor. Meanwhile, the hybrid electronic structure of the Ni-cluster/CN system was constructed, which was favorable for photocatalytic activity for hydrogen production. An in-depth understanding of the interfacial interaction between CN and Ni-clusters will have important reference significance on the mechanistic study of development based on the cocatalyst.