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Chinese Journal of Catalysis
2022, Vol. 43, No. 5
Online: 18 May 2022

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Cover: Ye and coworkers in their article on pages 1230–1237 reported that WO_3–x containing oxygen vacancies can be used to improve the selectivity of full-spectrum photocatalytic CO₂ reduction products. The C–C coupling mechanism of CO₂ photothermal catalytic reduction into C2 products (C₂H₄ and C₂H₆) has been verified.

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Editorial

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Preface to special issue on catalysing production of renewable fuels Hongwei Huang, Tianyi Ma, Antonio Tricoli 2022, 43 (5):  1193-1193.  DOI: 10.1016/S1872-2067(21)64039-1 Abstract ( 187 )   HTML ( 394 )   PDF (525KB) ( 208 )

Perspective

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Transforming catalysis to produce e-fuels: Prospects and gaps Georgia Papanikolaou, Gabriele Centi, Siglinda Perathoner, Paola Lanzafame 2022, 43 (5):  1194-1203.  DOI: 10.1016/S1872-2067(21)64016-0 Abstract ( 281 )   HTML ( 31 )   PDF (2693KB) ( 401 )   After short introducing the crucial role of e-fuels to meet net-zero emissions targets, this perspective paper discusses the differences between reactive catalysis (electro-, photo- and plasma-catalysis, with focus on the first for conciseness) and thermal catalysis used at most. The main point is to evidence that to progress in producing e-fuels, the gap is not in terms of scaling-up and pilot testing, but rather in the fundamental needs to turn the current approach and methodologies to develop reactive catalysis, including from a mechanistic perspective, to go beyond the current methods largely derived from thermal catalysis. Developing thus new fundamental bases to understand reactive catalysis is the challenge to accelerate the progress in this area to enable the potential role towards a sustainable net-zero emissions future. Some novel aspects are highlighted, but the general aim is rather to stimulate discussion in rethinking catalysis from an alternative perspective.

Reviews

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Photoelectrocatalytic hydrogen peroxide production based on transition-metal-oxide semiconductors Haijiao Lu, Xianlong Li, Sabiha Akter Monny, Zhiliang Wang, Lianzhou Wang 2022, 43 (5):  1204-1215.  DOI: 10.1016/S1872-2067(21)64028-7 Abstract ( 517 )   HTML ( 37 )   PDF (3207KB) ( 445 )   As a kind of valuable chemicals, hydrogen peroxide (H2O2) has aroused growing attention in many fields. However, H2O2 production via traditional anthraquinone process suffers from challenges of large energy consumption and heavy carbon footprint. Alternatively, photoelectrocatalytic (PEC) production of H2O2 has shown great promises to make H2O2 a renewable fuel to store solar energy. Transition-metal-oxide (TMO) semiconductor based photoelectrocatalysts are among the most promising candidates for PEC H2O2 production. In this work, the fundamentals of H2O2 synthesis through PEC process are briefly introduced, followed by the state-of-the-art of TMO semiconductor based photoelectrocatalysts for PEC production H2O2. Then, the progress on H2O2 fuel cells from on-site PEC production is presented. Furthermore, the challenges and future perspectives of PEC H2O2 production are discussed. This review aims to provide inspiration for the PEC production of H2O2 as a renewable solar fuel.

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Few-layer carbon nitride photocatalysts for solar fuels and chemicals: Current status and prospects Fangshuai Chen, Chongbei Wu, Gengfeng Zheng, Liangti Qu, Qing Han 2022, 43 (5):  1216-1229.  DOI: 10.1016/S1872-2067(21)63985-2 Abstract ( 226 )   HTML ( 16 )   PDF (5187KB) ( 274 )   Converting sunlight directly to fuels and chemicals is a great latent capacity for storing renewable energy. Due to the advantages of large surface area, short diffusion paths for electrons, and more exposed active sites, few-layer carbon nitride (FLCN) materials present great potential for production of solar fuels and chemicals and set off a new wave of research in the last few years. Herein, the recent progress in synthesis and regulation of FLCN-based photocatalysts, and their applications in the conversion of sunlight into fuels and chemicals, is summarized. More importantly, the regulation strategies from chemical modification to microstructure control toward the production of solar fuels and chemicals has been deeply analyzed, aiming to inspire critical thinking about the effective approaches for photocatalyst modification rather than developing new materials. At the end, the key scientific challenges and some future trend of FLCN-based materials as advanced photocatalysts are also discussed.

Communication

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Solar-energy-driven photothermal catalytic C-C coupling from CO2 reduction over WO3-x Yu Deng, Jue Li, Rumeng Zhang, Chunqiu Han, Yi Chen, Ying Zhou, Wei Liu, Po Keung Wong, Liqun Ye 2022, 43 (5):  1230-1237.  DOI: 10.1016/S1872-2067(21)63868-8 Abstract ( 447 )   HTML ( 17 )   PDF (1767KB) ( 365 )   Supporting Information Solar-energy-driven catalytic CO2 reduction for the production of value-added carbon-based materials and chemical raw materials has attracted great interest to alleviate the global climate change and energy crisis. The production of multicarbon (C2) products through CO2 reduction is extremely attractive, however, the yield and selectivity of C2 products remain low because of the low reaction temperature required and the low photoelectron density of the substrate. Here, we introduce WO3-x, which contains oxygen vacancies and exhibits an excellent photothermal conversion efficiency, to improve the generation of C2 products (C2H4 and C2H6) under simulated sunlight (UV-Vis-IR) irradiation. WO3-x produced 5.30 and 0.93 μmol·g-1 C2H4 and C2H6, respectively, after 4 h, with a selectivity exceeding 34%. In situ Fourier transform infrared spectra and theoretical calculations showed that the oxygen vacancies enhanced the water activation and hydrogenation of adsorbed CO for the formation of C2 products via C-C coupling from CH2/CH3 intermediates. The findings of this study could assist in the design of highly active solar-energy-driven catalysts to produce C-C coupling products through CO2 reduction.

Articles

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Interfacial engineering of heterogeneous molecular electrocatalysts using ionic liquids towards efficient hydrogen peroxide production Zixun Yu, Chang Liu, Yeyu Deng, Mohan Li, Fangxin She, Leo Lai, Yuan Chen, Li Wei 2022, 43 (5):  1238-1246.  DOI: 10.1016/S1872-2067(21)63946-3 Abstract ( 345 )   HTML ( 115 )   PDF (3418KB) ( 318 )   Supporting Information Efficient and selective oxygen reduction reaction (ORR) electrocatalysts are critical to realizing decentralized H2O2 production and utilization. Here we demonstrate a facile interfacial engineering strategy using a hydrophobic ionic liquid (IL, i.e., [BMIM][NTF2]) to boost the performance of a nitrogen coordinated single atom cobalt catalyst (i.e., cobalt phthalocyanine (CoPc) supported on carbon nanotubes (CNTs). We find a strong correlation between the ORR performance of CoPc/CNT and the thickness of its IL coatings. Detailed characterization revealed that a higher O2 solubility (2.12 × 10-3 mol/L) in the IL compared to aqueous electrolytes provides a local O2 enriched surface layer near active catalytic sites, enhancing the ORR thermodynamics. Further, the hydrophobic IL can efficiently repel the as-synthesized H2O2 molecules from the catalyst surface, preventing their fast decomposition to H2O, resulting in improved H2O2 selectivity. Compared to CoPc/CNT without IL coatings, the catalyst with an optimal ~8 nm IL coating can deliver a nearly 4 times higher mass specific kinetic current density and 12.5% higher H2O2 selectivity up to 92%. In a two-electrode electrolyzer test, the optimal catalyst exhibits an enhanced productivity of 3.71 molH2O2 gcat-1 h-1, and robust stability. This IL-based interfacial engineering strategy may also be extended to many other electrochemical reactions by carefully tailoring the thickness and hydrophobicity of IL coatings.

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Solution chemistry back-contact FTO/hematite interface engineering for efficient photocatalytic water oxidation Karen Cristina Bedin, Beatriz Mouriño, Ingrid Rodríguez-Gutiérrez, João Batista Souza Junior, Gabriel Trindade dos Santos, Jefferson Bettini, Carlos Alberto Rodrigues Costa, Lionel Vayssieres, Flavio Leandro Souza 2022, 43 (5):  1247-1257.  DOI: 10.1016/S1872-2067(21)63973-6 Abstract ( 465 )   HTML ( 14 )   PDF (2782KB) ( 338 )   Supporting Information This work describes a simple yet powerful scalable solution chemistry strategy to create back-contact rich interfaces between substrates such as commercial transparent conducting fluorine-doped tin oxide coated glass (FTO) and photoactive thin films such as hematite for low-cost water oxidation reaction. High-resolution electron microscopy (SEM, TEM, STEM), atomic force microscopy (AFM), elemental chemical mapping (EELS, EDS) and photoelectrochemical (PEC) investigations reveal that the mechanical stress, lattice mismatch, electron energy barrier, and voids between FTO and hematite at the back-contact interface as well as short-circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions, thus increasing the overall efficiency of these low-cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water-splitting. These findings are of significant importance to improve the charge collection efficiency by minimizing electron-hole recombination observed at back-contact interfaces and grain boundaries in mesoporous electrodes, thus improving the overall efficiency and scalability of low-cost PEC water splitting devices.

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Synergetic photocatalytic and thermocatalytic reforming of methanol for hydrogen production based on Pt@TiO2 catalyst Lei Li, Wenjun Ouyang, Zefeng Zheng, Kaihang Ye, Yuxi Guo, Yanlin Qin, Zhenzhen Wu, Zhan Lin, Tiejun Wang, Shanqing Zhang 2022, 43 (5):  1258-1266.  DOI: 10.1016/S1872-2067(21)63963-3 Abstract ( 498 )   HTML ( 36 )   PDF (1773KB) ( 349 )   Supporting Information In order to efficiently produce H2, conventional methanol-water thermocatalytic (TC) reforming requires a very high temperature due to high Gibbs free energy, while the energy conversion efficiency of methanol-water photocatalytic (PC) reforming is far from satisfaction because of the kinetic limitation. To address these issues, herein, we incorporate PC and TC processes together in a specially designed reactor and realize simultaneous photocatalytic/thermocatalytic (PC-TC) reforming of methanol in an aqueous phase. Such a design facilitates the synergetic effect of the PC and TC process for H2 production due to a lower energy barrier and faster reaction kinetics. The methanol-water reforming based on the optimized 0.05%Pt@TiO2 catalyst delivers an outstanding H2 production rate in the PC-TC process (5.66 μmol H2·g‒1 catalyst·s‒1), which is about 3 and 7 times than those of the TC process (1.89 μmol H2·g‒1 catalyst·s‒1) and the PC process (0.80 μmol H2·g‒1 catalyst·s‒1), respectively. Isotope tracer experiments, active intermediate trapping experiments, and theoretical calculations demonstrate that the photo-generated holes and hydroxyl radicals could enhance the methanol dehydrogenation, water molecule splitting, and water-gas shift reaction, while high temperature accelerates reaction kinetics. The proposed PC-TC reforming of methanol for hydrogen production can be a promising technology to solve the energy and environmental issue in the closed-loop hydrogen economy in the near future.

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Sea urchin-like NiMoO4 nanorod arrays as highly efficient bifunctional catalysts for electrocatalytic/photovoltage-driven urea electrolysis Chenxin Chen, Suqi He, Kamran Dastafkan, Zehua Zou, Qingxiang Wang, Chuan Zhao 2022, 43 (5):  1267-1276.  DOI: 10.1016/S1872-2067(21)63962-1 Abstract ( 429 )   HTML ( 17 )   PDF (6953KB) ( 403 )   Supporting Information Developing multifunctional electrocatalysts with high catalytic activity, long-term stability, and low cost is essential for electrocatalytic energy conversion. Herein, sea urchin-like NiMoO4 nanorod arrays grown on nickel foam has been developed as a bifunctional electrocatalyst for urea oxidation and hydrogen evolution. The NiMoO4-200/NF catalyst exhibits efficient activity toward hydrogen evolution reaction with a low overpotential of only 68 mV in 1.0 mol/L KOH to gain a current density of 10 mA cm-2. The NiMoO4-300/NF catalyst exhibits a prominent oxygen evolution reaction (OER) catalytic activity with an overpotential of 288 mV at 50 mA cm-2, as well as for urea oxidation reaction with an ultra-low potential of 1.36 V at 10 mA cm-2. The observed difference in electrocatalytic activity and selectivity, derived by temperature variation, is ascribed to different lattice oxygen contents. The lattice oxygen of NiMoO4-300/NF is more than that of NiMoO4-200/NF, and the lattice oxygen is conducive to the progress of OER. A urea electrolyzer was assembled with NiMoO4-200/NF and NiMoO4-300/NF as cathode and anode respectively, delivering a current density of 10 mA cm-2 at a cell voltage of merely 1.38 V. The NiMoO4 nanorod arrays has also been successfully applied for photovoltage-driven urea electrolysis and hydrogen production, revealing its great potential for solar-driven energy conversion.

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Engineering piezoelectricity and strain sensitivity in CdS to promote piezocatalytic hydrogen evolution Jingjing Wang, Cheng Hu, Yihe Zhang, Hongwei Huang 2022, 43 (5):  1277-1285.  DOI: 10.1016/S1872-2067(21)63976-1 Abstract ( 414 )   HTML ( 23 )   PDF (3229KB) ( 453 )   Supporting Information Piezocatalytic hydrogen evolution has emerged as a promising direction for the collection and utilization of mechanical energy and the efficient generation of sustainable energy throughout the day. Hexagonal CdS, as an established semiconductor photocatalyst, has been widely investigated for splitting water into H2, while its piezocatalytic performance has attracted less attention, and the relationship between the structure and piezocatalytic activity remains unclear. Herein, two types of CdS nanostructures, namely CdS nanorods and CdS nanospheres, were prepared to probe the above-mentioned issues. Under ultrasonic vibration, the CdS nanorods afforded a superior piezocatalytic H2 evolution rate of 157 μmol g-1 h-1 in the absence of any co-catalyst, which is nearly 2.8 times that of the CdS nanospheres. The higher piezocatalytic activity of the CdS nanorods is derived from their larger piezoelectric coefficient and stronger mechanical energy harvesting capability, affording a greater piezoelectric potential and more efficient separation and transfer of intrinsic charge carriers, as elucidated through piezoelectric response force microscopy, finite element method, and piezoelectrochemical tests. This study provides a new concept for the design of efficient piezocatalytic materials for converting mechanical energy into sustainable energy via microstructure regulation.

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Multidimensional In2O3/In2S3 heterojunction with lattice distortion for CO2 photoconversion Jinman Yang, Xingwang Zhu, Qing Yu, Minqiang He, Wei Zhang, Zhao Mo, Junjie Yuan, Yuanbin She, Hui Xu, Huaming Li 2022, 43 (5):  1286-1294.  DOI: 10.1016/S1872-2067(21)63954-2 Abstract ( 242 )   HTML ( 13 )   PDF (2729KB) ( 330 )   Supporting Information Photocatalytic CO2 reduction to sustainably product of fuels is a potential route to achieve clean energy conversion. Unfortunately, the sluggish charge transport dynamics and poor CO2 activation performance result in a low CO2 conversion efficiency. Herein, we develop a multidimensional In2O3/In2S3 (IO/IS) heterojunction with abundant lattice distortion structure and high concentration of oxygen defects. The close contact interfaces between the junction of the two phases ensure undisturbed transmission of electrons with high-speed. The increased free electron concentration promotes the adsorption and activation of CO2 on the catalyst surface, leaving the key intermediate *COOH at a lower energy barrier. The perfect combination of the band matching oxide and sulfide effectively reduces the internal energy barrier of the CO2 reduction reaction. Furthermore, the lattice distortion structure not only provides additional active sites, but also optimizes the kinetics of the reaction through microstructural regulation. Remarkably, the optimal IO/IS heterojunction exhibits superior CO2 reduction performance with CO evolution rate of 12.22 μmol g-1 h-1, achieving about 4 times compared to that of In2O3 and In2S3, respectively. This work emphasizes the importance of tight interfaces of heterojunction in improving the performance of CO2 photoreduction, and provides an effective strategy for construction of heterojunction photocatalysts.

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Synthesis of ternary Ni2P@UiO-66-NH2/Zn0.5Cd0.5S composite materials with significantly improved photocatalytic H2 production performance Aixia Wang, Linhe Zhang, Xuli Li, Yangqin Gao, Ning Li, Guiwu Lu, Lei Ge 2022, 43 (5):  1295-1305.  DOI: 10.1016/S1872-2067(21)63912-8 Abstract ( 225 )   HTML ( 19 )   PDF (5233KB) ( 395 )   abstract The design and construction of low-cost and high-performance hybrid materials for the photocatalytic hydrogen production reaction (HER) are extremely important for the large-scale application of hydrogen energy. Metal-organic frameworks (MOFs) are considered to be potential photocatalytic materials. Herein, monodisperse, small size, non-precious metal transition metal phosphide Ni2P is encapsulated into a typical MOF (UiO-66-NH2) as a hybrid core-shell cocatalyst to modify Zn0.5Cd0.5S for photocatalytic hydrogen production. Ni2P is wrapped in UiO-66-NH2 via an in situ solvothermal method, and Zn0.5Cd0.5S sulfide is decorated with a core-shell Ni2P@UiO-66-NH2 cocatalyst to obtain ternary Ni2P@UiO-66-NH2/Zn0.5Cd0.5S composite materials. Photoelectric and chemical characterization confirms that the ternary composites have good kinetic hydrogen production performance. The hydrogen production rate of 10% 10 mg Ni2P@UiO-66-NH2/Zn0.5Cd0.5S reaches 40.91 mmol·g-1·h-1 with an apparent quantum efficiency at 420 nm of 13.57%. The addition of 10 mg Ni2P@UiO-66-NH2 increases the surface area of the ternary material, providing abundant reaction sites and forming an efficient charge transfer channel, which is conducive to efficient hydrogen production by the ternary photocatalysts. It is shown that the formation of a ternary composite system is beneficial to the occurrence of an efficient catalytic reaction. This study provides a new perspective for the construction of high-performance photocatalytic materials.

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2D metal-free heterostructure of covalent triazine framework/g-C3N4 for enhanced photocatalytic CO2 reduction with high selectivity Jie He, Xuandong Wang, Shangbin Jin, Zhao-Qing Liu, Mingshan Zhu 2022, 43 (5):  1306-1315.  DOI: 10.1016/S1872-2067(21)63936-0 Abstract ( 317 )   HTML ( 27 )   PDF (1823KB) ( 256 )   Supporting Information Solar-driven CO2 conversion to precious fossil fuels has been proved to become a potential way to decrease CO2 with producing renewable fuels, which mainly relies on photocatalysts with efficient charge separation. In this work, a metal free heterostructure of covalent triazine framework (CTF) and graphite carbon nitride (g-C3N4, abbreviated as CN) is applied in the CO2 photoreduction for the first time. Detailed characterization methods such as photoluminescence (PL) and time-resolved PL (TR-PL) decay are utilized to reveal the photo-induced carries separating process on g-C3N4/CTF (CN/CTF) heterostructure. The introduced CTF demonstrated a great boosting photocatalytic activity for CN, bringing about the transform rates of CO2 to CO reaching 151.1 μmol/(g·h) with a 30 h stabilization time, while negligible CH4 was detected. The optimal CN/CTF heterostructure could more efficiently separate charges with a lower probability of recombination under visible light irradiation, which made the photoreduction efficiency of CO2 to CO be 25.5 and 2.5 times higher than that of CTF and CN, respectively. This investigation is expected to offer a new thought for fabricating high-efficiency photocatalyst without metal in solar-energy-driven CO2 reduction.

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Synergistic promotion of HER and OER by alloying ternary Zn-Co-Ni nanoparticles in N-doped carbon interfacial structures Limei Lu, Yihe Zhang, Zhensheng Chen, Feng Feng, Kaixuan Teng, Shuting Zhang, Jialin Zhuang, Qi An 2022, 43 (5):  1316-1323.  DOI: 10.1016/S1872-2067(21)63938-4 Abstract ( 218 )   HTML ( 15 )   PDF (2187KB) ( 282 )   Catalytic water splitting potentially reduce the consumption of fossil fuels and has received intense research attention. Synergy effects in multi-element transition metal-based water splitting catalysts have evoked special interests. Studies on catalysts in interfacial structures are especially meaningful due to their pertinence in applications. In this study, we report the synergy effects in promoting catalytic power in the ternary transition metal Zn, Co, Ni alloy nanoparticles that embeds in the carbonized Ppy/CNT multilayered matrix. By comparison with a series of binary or single metal counterparts, the mechanism under the synergy effects are elucidated. Experimental and DFT calculation results indicate that the ternary transition metal catalysts in the N-doped carbon matrix present special electronic structure, which benefits the reversible transition-state adsorption in HER and OER and render the catalysts high conductivity in room temperature. We expect our findings inspire further development of efficient transition metal HER and OER catalysts.

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“Electron collector” Bi19S27Br3 nanorod-enclosed BiOBr nanosheet for efficient CO2 photoconversion Junze Zhao, Min Xue, Mengxia Ji, Bin Wang, Yu Wang, Yingjie Li, Ziran Chen, Huaming Li, Jiexiang Xia 2022, 43 (5):  1324-1330.  DOI: 10.1016/S1872-2067(21)64037-8 Abstract ( 186 )   HTML ( 14 )   PDF (4263KB) ( 310 )   Supporting Information Although CO2 photoreduction is a promising method for solar-to-fuel conversion, it suffers from low charge transfer efficiency of the photocatalysts. To improve the CO2 photoreduction performance, introduction of electron-accumulated materials on the photocatalyst surface is considered an effective method. In this study, the Bi19S27Br3/BiOBr composites were designed and synthesized. The Bi19S27Br3 nanorod in this photocatalytic system acts as an electron-accumulated active site for extracting the photogenerated electrons on the BiOBr surface and for effectively activating the CO2 molecules. As a result, Bi19S27Br3/BiOBr composites exhibit the higher charge carrier transfer efficiency and further improves the CO2 photoreduction performance relative to that of pure Bi19S27Br3 and BiOBr. The rate of CO formation using Bi19S27Br3/BiOBr-5 is about 8.74 and 2.40 times that using Bi19S27Br3 and BiOBr, respectively. This work provides new insights for the application of Bi19S27Br3 as an electron-accumulating site for achieving high photocatalytic CO2 reduction performance in the future.

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Construction of 2D Zn-MOF/BiVO4 S-scheme heterojunction for efficient photocatalytic CO2 conversion under visible light irradiation Zhenlong Zhao, Ji Bian, Lina Zhao, Hongjun Wu, Shuai Xu, Lei Sun, Zhijun Li, Ziqing Zhang, Liqiang Jing 2022, 43 (5):  1331-1340.  DOI: 10.1016/S1872-2067(21)64005-6 Abstract ( 371 )   HTML ( 24 )   PDF (2028KB) ( 405 )   Supporting Information The construction of S-scheme heterojunction photocatalysts has been regarded as an effective avenue to facilitate the conversion of solar energy to fuel. However, there are still considerable challenges with regard to efficient charge transfer, the abundance of catalytic sites, and extended light absorption. Herein, an S-scheme heterojunction of 2D/2D zinc porphyrin-based metal-organic frameworks/BiVO4 nanosheets (Zn-MOF/BVON) was fabricated for efficient photocatalytic CO2 conversion. The optimal one shows a 22-fold photoactivity enhancement when compared to the previously reported BiVO4 nanoflake (ca. 15 nm), and even exhibits ~2-time improvement than the traditional g-C3N4/BiVO4 heterojunction. The excellent photoactivities are ascribed to the strengthened S-scheme charge transfer and separation, promoted CO2 activation by the well-dispersed metal nodes Zn2(COO)4 in the Zn-MOF, and extended visible light response range based on the results of the electrochemical reduction, electron paramagnetic resonance, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The dimension-matched Zn-MOF/BVON S-scheme heterojunction endowed with highly efficient charge separation and abundant catalytic active sites contributed to the superior CO2 conversion. This study offers a facile strategy for constructing S-scheme heterojunctions involving porphyrin-based MOFs for solar fuel production.

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Improved nitrogen reduction electroactivity by unique MoS2-SnS2 heterogeneous nanoplates supported on poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide Hui Mao, Haoran Yang, Jinchi Liu, Shuai Zhang, Daliang Liu, Qiong Wu, Wenping Sun, Xi-Ming Song, Tianyi Ma 2022, 43 (5):  1341-1350.  DOI: 10.1016/S1872-2067(21)63944-X Abstract ( 257 )   HTML ( 14 )   PDF (2681KB) ( 272 )   Supporting Information Unique MoS2-SnS2 heterogeneous nanoplates have successfully in-situ grown on poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) functionalized polypyrrole/ graphene oxide (PVIPS/PPy/GO). PVIPS can attract heptamolybdate ion (Mo7O246-) and Sn4+ as the precursors by the ion-exchange, resulting in the simultaneous growth of 1T’-MoS2 and the berndtite-2T-type hexagonal SnS2 by the interfacial induced effect of PVIPS. The obtained MoS2-SnS2/ PVIPS/PPy/GO can serve as electrocatalysts, exhibiting good NRR performance by the synergistic effect. The semi-conducting SnS2 would limit the surface electron accessibility for suppressing HER process of 1T’-MoS2, while metallic 1T’-MoS2 might efficiently improve the NRR electroactivity of SnS2 by the creation of Mo-Sn-Sn trimer catalytic sites. Otherwise, the irreversible crystal phase transition has taken place during the NRR process. Partial 1T’-MoS2 and SnS2 have electrochemically reacted with N2, and irreversibly converted into Mo2N and SnxNz due to the formation of Mo-N and Sn-N bonding, meanwhile, partial SnS2 has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system. It would put forward a new design idea for optimizing the preparation method and electrocatalytic activity of transition metal dichalcogenides.

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Toward enhanced alkaline hydrogen electrocatalysis with transition metal-functionalized nitrogen-doped carbon supports Peng Li, Guoqiang Zhao, Ningyan Cheng, Lixue Xia, Xiaoning Li, Yaping Chen, Mengmeng Lao, Zhenxiang Cheng, Yan Zhao, Xun Xu, Yinzhu Jiang, Hongge Pan, Shi Xue Dou, Wenping Sun 2022, 43 (5):  1351-1359.  DOI: 10.1016/S1872-2067(21)63935-9 Abstract ( 252 )   HTML ( 13 )   PDF (2125KB) ( 290 )   Supporting Information Superior catalyst supports are crucial to developing advanced electrocatalysts toward heterogeneous catalytic reactions. Herein, we systematically investigate the role of transition metal-functionalized N-doped carbon nanosheets (M-N-C, M = Mn, Fe, Co, Ni, Cu, Mo, and Ag) as the multifunctional electrocatalyst supports toward hydrogen evolution/oxidation reactions (HER/HOR) in alkaline media. The results demonstrate that all the M-N-C nanosheets, except Cu-N-C and Ag-N-C, can promote the alkaline HER/HOR electrocatalytic activity of Pt by accelerating the sluggish Volmer step, among which Mn plays a more significant role. Analyses reveal that the promotion effect of M-N-C support is closely associated with the electronegativity of the metal dopants and the relative filling degree of their d-orbitals. For one, the metal dopant in M-N-C with smaller electronegativity would provide more electrons to oxygen and hence tune the electronic structure of Pt via the M-O-Pt bonds at the interface. For another, the transition metal in M-N4 moieties with more empty d orbitals would hybridize with O 2p orbitals more strongly that promotes the adsorption of water/hydroxyl species. The results demonstrate the conceptual significance of multifunctional supports and would inspire the future development of advanced electrocatalysts.

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Ag nanoparticles anchored organic/inorganic Z-scheme 3DOMM-TiO2‒x-based heterojunction for efficient photocatalytic and photoelectrochemical water splitting Zhiying Xu, Chunyu Guo, Xin Liu, Ling Li, Liang Wang, Haolan Xu, Dongke Zhang, Chunhu Li, Qin Li, Wentai Wang 2022, 43 (5):  1360-1370.  DOI: 10.1016/S1872-2067(21)63978-5 Abstract ( 181 )   HTML ( 16 )   PDF (3799KB) ( 266 )   Supporting Information Narrow spectral response, low charge separation efficiency and slow water oxidation kinetics of TiO2 limit its application in photoelectrochemical and photocatalytic water splitting. Herein, a promising organic/inorganic composite catalyst Ag/PANI/3DOMM-TiO2-x with a three-dimensional ordered macro-and meso-porous (3DOMM) structure, oxygen vacancy and Ti3+ defects, heterojunction formation and noble metal Ag was designed based on the Z-scheme mechanism and successfully prepared. The Ag/PANI/3DOMM-TiO2-x ternary catalyst exhibited enhanced hydrogen production activity in both photocatalytic and photoelectrochemical water splitting. The photocatalytic hydrogen production rate is 420.90 μmol g-1 h-1, which are 19.80 times and 2.06 times higher than the commercial P25 and 3DOMM-TiO2, respectively. In the photoelectrochemical tests, the Ag/PANI/3DOMM-TiO2-x photoelectrode shows enhanced separation and transfer of carriers with a high current density of 1.55 mA cm-2 at equilibrium potential of 1.23 V under simulated AM 1.5 G illumination, which is approximately 5 times greater than the 3DOMM-TiO2. The present work has demonstrated the promising potential of organic/inorganic Z-scheme photocatalyst in driving water splitting for hydrogen production.

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Electrocatalytic ammonia synthesis catalyzed by mesoporous nickel oxide nanosheets loaded with Pt nanoparticles Wei Xiong, Min Zhou, Hao Li, Zhao Ding, Da Zhang, Yaokang Lv 2022, 43 (5):  1371-1378.  DOI: 10.1016/S1872-2067(21)63877-9 Abstract ( 316 )   HTML ( 11 )   PDF (1695KB) ( 270 )   Supporting Information Owing to its cost-effectiveness and adjustable eight-electron distribution in the 3d orbital, nickel oxide (NiO) is considered an effective electrocatalyst for an ambient electrochemical nitrogen reduction reaction (NRR). However, because of the low conductivity of the transition metal oxide electrocatalyst, its application in this field is limited. In this study, we found that the doping of NiO nanosheets with a small amount (3-10 nm) of Pt nanoparticles (Pt/NiO-NSs) leads to considerable improvements in the Faradaic efficiency (FE) and NH3 yield compared with those obtained using pure NiO, breaking the common perception that commercial Pt-based electrocatalysts demonstrate little potential for NRR due to their high hydrogen evolution tendency. In a 0.1 mol/L Na2SO4 solution at -0.2 V vs. RHE, a typical Pt/NiO-2 sample exhibits an optimum electrochemical NH3 yield of 20.59 μg h-1 mg-1cat. and an FE of 15.56%, which are approximately 5 and 3 times greater, respectively, than those of pure NiO nanosheets at the same applied potential. X-ray photoelectron spectroscopy analysis revealed that Pt in Pt/NiO-NSs exist as Pt0, Pt2+, and Pt4+ and that high-valence Pt ions are more electropositive, thereby favoring chemisorption and the activation of N2 molecules. Density function theory calculations showed that the d-band of Pt nanoparticles supported on NiO is significantly tuned compared to that of pure Pt, affording a more favorable electronic structure for NRR. The results of this study show that Pt can be an effective NRR electrochemical catalyst when loaded on an appropriate substrate. Most importantly, it provides a new synthetic avenue for the fabrication of highly active Pt-based NRR electrocatalysts.