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Chinese Journal of Catalysis
2020, Vol. 41, No. 2
Online: 18 February 2020

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Cover: Hao and coauthors in their Article on pages 249-258 reported a facile synthesis of bismuth sulfide nanoparticle modified graphitic carbon nitride and the composite materials exhibited excellent photocatalytic performance under simulated sunlight irradiation.The authors employed the photothermal effect,high-energy electron theory and electron paramagnetic resonance spectra to clarify the reaction mechanism.

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Table of Contents for VOL.41 No.2 2020, 41 (2):  0-0.  Abstract ( 29 )   PDF (2507KB) ( 62 )

Review

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Application of atomic layer deposition in fabricating high-efficiency electrocatalysts Huimin Yang, Yao Chen, Yong Qin 2020, 41 (2):  227-241.  DOI: 10.1016/S1872-2067(19)63440-6 Abstract ( 246 )   [Full Text(HTML)] () PDF (1941KB) ( 400 )   Electrocatalysis is a promising approach to clean energy conversion due to its high efficiency and low environmental pollution. Noble metal materials have been studied to show high activity toward electrocatalyltic reactions, although such applications remain restricted by the high cost and poor durability of the noble metals. By precisely adjusting the catalyst composition, size, and structure, electrocatalysts with excellent performance can be obtained. Atomic layer deposition (ALD) is a technique used to produce ultrathin films and ultrafine nanoparticles at the atomic level. It possesses unique advantages for the controllable design and synthesis of electrocatalysts. Furthermore, the homogenous composition and structure of the electrocatalysts prepared by ALD favor the exploration of structure-reactivity relationships and catalytic mechanisms. In this review, the mechanism, characteristics, and advantages of ALD in fabricating nanostructures are introduced first. Subsequently, the problems associated with existing electrocatalysts and a series of recently developed ALD strategies to enhance the activity and durability of electrocatalysts are presented. For example, the deposition of ultrafine Pt nanoparticles to increase the utilization and activity of Pt, fabrication of core-shell, overcoat, nanotrap, and other novel structures to protect the noble-metal nanoparticles and enhance the catalyst stability. In addition, ALD developments in synthesizing non-noble metallic electrocatalysts are summarized and discussed. Finally, based on the current studies, an outlook for the ALD application in the design and synthesis of electrocatalysts is presented.

Communication

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In situ assembly of metal-organic framework-derived N-doped carbon/Co/CoP catalysts on carbon paper for water splitting in alkaline electrolytes Meiyu Cong, Deshuai Sun, Linlin Zhang, Xin Ding 2020, 41 (2):  242-248.  DOI: 10.1016/S1872-2067(19)63410-8 Abstract ( 72 )   [Full Text(HTML)] () PDF (3573KB) ( 418 )   Supporting Information High-performance and cost-effective catalysts for water splitting are key components of hydrogen-based energy technologies. Metal-organic framework (MOF)-derived metal phosphide composites have immense potential as highly active and stable electrocatalysts but suffer from the poor efficacy of available electrode assembly methods. In this study, an MOF-derived nitrogen-doped porous carbon/Co/CoP/carbon paper (NC/Co/CoP/CP) composite electrode was assembled by electrophoretic deposition and post-processing reactions. The binder-free electrode showed good catalytic activity, significantly higher than that of traditional electrodes. The electrode required overpotentials of 208 and 350 mV to achieve a current density of 10 mA/cm2 for the hydrogen and oxygen evolution reactions, respectively. This facile synthetic method provides a promising route for designing metal-doped and multi-metal phase MOF-derived composite electrodes for energy storage and conversion devices.

Articles

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Accelerated separation of photogenerated charge carriers and enhanced photocatalytic performance of g-C3N4 by Bi2S3 nanoparticles Qiang Hao, Ci'an Xie, Yongming Huang, Daimei Chen, Yiwen Liu, Wei Wei, Bing-Jie Ni 2020, 41 (2):  249-258.  DOI: 10.1016/S1872-2067(19)63450-9 Abstract ( 136 )   [Full Text(HTML)] () PDF (1706KB) ( 494 )   Supporting Information Employing photothermal conversion to improve the photocatalytic activity of g-C3N4 is rarely reported previously. Herein, different ratios of g-C3N4/Bi2S3 heterojunction materials are synthesized by a facile ultrasonic method. Advanced characterizations such as X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy are employed to analyze the morphology and structure of the prepared materials. Compared with sole counterparts, the heterojunction materials CN-BiS-2 exhibit significantly enhanced photocatalytic performance, which is 2.05-fold as g-C3N4 and 4.42-fold as Bi2S3. A possible degradation pathway of methylene blue (MB) was proposed. Based on the photoproduced high-energy electrons and photothermal effect of Bi2S3, the transfer and separation of electron-hole pairs are greatly enhanced and more active species are produced. In addition, the relatively high utilization efficiency of solar energy has synergistic effect for the better photocatalytic performance.

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Phosphonate-derived nitrogen-doped cobalt phosphate/carbon nanotube hybrids as highly active oxygen reduction reaction electrocatalysts Hui Zhao, Chen-Chen Weng, Jin-Tao Ren, Li Ge, Yu-Ping Liu, Zhong-Yong Yuan 2020, 41 (2):  259-267.  DOI: 10.1016/S1872-2067(19)63455-8 Abstract ( 130 )   [Full Text(HTML)] () PDF (2914KB) ( 342 )   Supporting Information The exploration of cost-effective non-noble-metal electrocatalysts is highly imperative to replace the state-of-the-art platinum-based catalysts for oxygen reduction reaction (ORR). Here, we prepared cobalt phosphonate-derived N-doped cobalt phosphate/carbon nanotube hybrids (CoPiC-N/CNTs) by hydrothermal treatment of N-containing cobalt phosphonate and oxidized carbon nanotubes (o-CNT) followed by high-temperature calcination under nitrogen atmosphere. The resultant CoPiC-N/CNT exhibits a superior electrocatalytic performance for the ORR in alkaline media, which is equal to the commercial Pt/C catalyst in the aspect of half-wave potential, onset potential and diffuse limiting current density. Furthermore, the excellent tolerance to methanol and strong durability outperform those of commercial Pt/C. It is found that cobalt phosphonate-derived N-doped cobalt phosphate and the in-situ formed graphitic carbons play key roles on the activity enhancement. Besides, introducing a suitable amount of CNTs enhances the electronic conductivity and further contributes to the improved ORR performance.

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Facile construction of Bi2Mo3O12@Bi2O2CO3 heterojunctions for enhanced photocatalytic efficiency toward NO removal and study of the conversion process Wangchen Huo, Tong Cao, Weina Xu, Ziyang Guo, Xiaoying Liu, Hong-Chang Yao, Yuxin Zhang, Fan Dong 2020, 41 (2):  268-275.  DOI: 10.1016/S1872-2067(19)63460-1 Abstract ( 44 )   [Full Text(HTML)] () PDF (3049KB) ( 290 )   Supporting Information Charge separation and transformation are some of the key requirements for high-efficiency photocatalysis. The photocatalytic reaction mechanism provides a guideline for the development and commercialization of high-efficiency photocatalysts. In this study, we designed and favorably synthesized BMO@BOC heterojunctions via a facile solvothermal route and applied the heat treatment method for application in high-efficiency photocatalytic NO removal. More importantly, both continuous stream and intermittent stream methods with in situ diffuse reflectance infrared Fourier transform spectroscopy were applied to intuitively and dynamically investigate the adsorption process and oxidation process of NO removal over the photocatalyst surface. The intermediate products (NO-, NO2-, and NO2) were explicitly detected in both the adsorption process and oxidation process, whilst the final product (NO3-) appeared only in the oxidation process, owing to the separation, migration, and conversion of photoinduced electron-hole pairs.

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Nature of active phase of VOx catalysts supported on SiBeta for direct dehydrogenation of propane to propylene Chong Chen, Minglei Sun, Zhongpan Hu, Yuping Liu, Shoumin Zhang, Zhong-Yong Yuan 2020, 41 (2):  276-285.  DOI: 10.1016/S1872-2067(19)63444-3 Abstract ( 112 )   [Full Text(HTML)] () PDF (838KB) ( 385 )   Supporting Information The VOx catalysts supported on dealuminated Beta zeolite (SiBeta) with varying V loadings (from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane to propylene (PDH). It is characterized that the VSiBeta catalysts possess different kinds of vanadium species on the SiBeta support, including monomeric or isolated VOx species at a low V loading, and polynuclear VOx species in different polymerization degrees at higher V loadings. The 3VSiBeta catalyst (V loading is 3 wt%), containing isolated VOx species in monolayer, shows around 40% of propane conversion with 90% of propylene selectivity (reaction conditions:600 ℃, 4000 mL g-1 h-1) which are comparable to VSiBeta catalysts with higher V loadings. The catalytic activity exhibits a good linear relationship with the amount of generated acidic sites, which are derived from the interaction sites between VOx species and SiBeta support, and keeps stable after several regeneration cycles. Thus, as the VOx species directly contact with SiBeta support via V-O-Si bonds, a reactivity enhancement can be achieved. While, the initial valence state of V does not seem to influence the catalytic performance. Moreover, the aggregation degree of VOx species determines the propylene selectivity and deactivation rate, both of which increase as raising the V loading amount.

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Visible light-enhanced photothermal CO2 hydrogenation over Pt/Al2O3 catalyst Ziyan Zhao, Dmitry E. Doronkin, Yinghao Ye, Jan-Dierk Grunwaldt, Zeai Huang, Ying Zhou 2020, 41 (2):  286-293.  DOI: 10.1016/S1872-2067(19)63445-5 Abstract ( 90 )   [Full Text(HTML)] () PDF (1273KB) ( 380 )   Supporting Information Light illumination has been widely used to promote activity and selectivity of traditional thermal catalysts. Nevertheless, the role of light irradiation during catalytic reactions is not well understood. In this work, Pt/Al2O3 prepared by wet impregnation was used for photothermal CO2 hydrogenation, and it showed a photothermal effect. Hence, operando diffuse reflectance infrared Fourier-transform spectroscopy and density functional theory calculations were conducted on Pt/Al2O3 to gain insights into the reaction mechanism. The results indicated that CO desorption from Pt sites including step sites (Ptstep) or/and terrace site (Ptterrace) is an important step during CO2 hydrogenation to free the active Pt sites. Notably, visible light illumination and temperature affected the CO desorption in different ways. The calculated adsorption energy of CO on Ptstep and Ptterrace sites was -1.24 and -1.43 eV, respectively. Hence, CO is more strongly bound to the Ptstep sites. During heating in the dark, CO preferentially desorbs from the Ptterrace site. However, the additional light irradiation facilitates transfer of CO from the Ptstep to Ptterrace sites and its subsequent desorption from the Ptterrace sites, thus promoting the CO2 hydrogenation.

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General trends in Horiuti-Polanyi mechanism vs non-Horiuti-Polanyi mechanism for water formation on transition metal surfaces Xitong Sun, Jianfu Chen, P. Hu 2020, 41 (2):  294-301.  DOI: 10.1016/S1872-2067(19)63434-0 Abstract ( 341 )   [Full Text(HTML)] () PDF (2687KB) ( 377 )   It is generally acknowledged in heterogeneous catalysis that hydrogenation follows the so-called Horiuti-Polanyi (HP) mechanism. In this work, a thorough investigation of the mechanism of hydrogenation of hydroxyl groups and O catalyzed by a series of transition metals was carried out through density functional theory calculations, as surface hydroxyls and O are very common species in many catalytic systems. It is found that different metal catalysts exhibit different mechanisms. On some metal catalysts, the non-HP mechanism is preferred, whereas the classic HP mechanism is favored on other catalysts. Detailed analyses of the metal-dependent mechanism shows that the activity toward the dissociation of H2 decides which mechanism is preferred. On active catalysts, such as Ni and Pt, H2 prefers to dissociate with strong H adsorption energies, which lead to the classic HP mechanism being favored. On inactive surfaces, on the other hand, the adsorption of H is weak, which results in the non-HP mechanism being preferred. The parameter η, which is a structural descriptor, was defined to understand the different mechanisms.

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Preparation of BiPO4/graphene photoelectrode and its photoelectrocatalyitic performance Zetian He, Sen Liu, Yi Zhong, Daimei Chen, Hao Ding, Jiao Wang, Gaoxiang Du, Guang Yang, Qiang Hao 2020, 41 (2):  302-311.  DOI: 10.1016/S1872-2067(19)63520-5 Abstract ( 105 )   [Full Text(HTML)] () PDF (4079KB) ( 335 )   In this work, a two-step electrodeposition method was employed to prepare BiPO4 nanorod/reduced graphene oxide/FTO composite electrodes (BiPO4/rGO/FTO). The BiPO4/rGO/FTO composite electrode showed the higher photoelectrocatalytic (PEC) activity for the removal of methyl orange than pure BiPO4, which was 2.8 times higher than that of BiPO4/FTO electrode. The effects of working voltage and BiPO4 deposition time on the degradation efficiency of methyl orange were investigated. The optimum BiPO4 deposition time was 45 min and the optimum working voltage was 1.2 V. The trapping experiments showed that hydroxyl radicals (·OH) and superoxide radicals (·O2-) were the major reactive species in PEC degradation process. The BiPO4/rGO/FTO composite electrode showed the high stability and its methyl orange removal efficiency remained unchanged after four testing cycles. The reasons for the enhanced PEC efficiency of the BiPO4/rGO/FTO composite electrode was ascribed to the broad visible-light absorption range, the rapid transmission of photogenerated charges, and the mixed BiPO4 phase by the introduction of rGO in the composite electrode films.

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Heterogeneous interfacial engineering of Pd/TiO2 with controllable carbon content for improved direct synthesis efficiency of H2O2 Wei Yan, Rui Sun, Meng Li, Licheng Li, Zhuhong Yang, Zelin Hua, Xiaohua Lu, Chang Liu 2020, 41 (2):  312-321.  DOI: 10.1016/S1872-2067(19)63412-1 Abstract ( 92 )   [Full Text(HTML)] () PDF (1035KB) ( 333 )   Supporting Information Series of heterogeneous interfacial engineered TiO2 (C-TiO2) with controllable carbon content were facilely synthesized by incipient-wet impregnation using glucose and subsequent thermal carbonization. The obtained C-TiO2 were used as catalytic supports to load Pd nanoparticles for H2O2 direct synthesis from H2 and O2. The as-prepared samples were systematically studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), air isothermal microcalorimeter, temperature-programmed reduction of H2 (H2-TPR), and so on. The catalytic results showed that H2O2 productivity and H2O2 selectivity of Pd/C-TiO2 firstly rose with increasing carbon content and then declined. Pd/C-TiO2 catalyst with 1.89 wt% of carbon content showed the best catalytic performance that had 61.2% of selectivity and 2192 mmol H2O2/gPd/h of productivity, which were significantly better than those of pristine Pd/TiO2 (45.2% and 1827 mmol H2O2/gPd/h). Various characterization results displayed that the carbon species were heterogeneously dispersed on TiO2 surface. Moreover, no obvious geometric transformation in supports and Pd nanoparticles were observed among different catalysts. The superficial hydrophobicity of Pd/C-TiO2 was gradually promoted with increasing carbon content, which led to the corresponding decrease in adsorption energy of H2O2 with catalysts. According to structure-performance relationship analyses, the heterogeneous interfacial engineering of carbon could maintain the interaction of Pd nanoparticles with TiO2 and simultaneously accelerate the H2O2 desorption. Both factors further determined the excellent H2O2 direct synthesis performance of Pd/C-TiO2.

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Mechanistic studies on peroxymonosulfate activation by g-C3N4 under visible light for enhanced oxidation of light-inert dimethyl phthalate Lijie Xu, Lanyue Qi, Yang Sun, Han Gong, Yiliang Chen, Chun Pei, Lu Gan 2020, 41 (2):  322-332.  DOI: 10.1016/S1872-2067(19)63447-9 Abstract ( 98 )   [Full Text(HTML)] () PDF (941KB) ( 344 )   Supporting Information Excitation of metal-free graphitic carbon nitride (g-C3N4) under visible light can successfully achieve efficient activation of peroxymonosulfate (PMS). Synergistic effects and involved mechanism were systematically investigated using a light-inert endocrine disrupting compound, dimethyl phthalate (DMP), as the target pollutant. Under visible light irradiation, DMP could not be degraded by direct g-C3N4-mediated photocatalysis, while in the presence of PMS, the dominant radicals were converted from ·O2 to SO4·- and ·OH, resulting in effective DMP degradation and mineralization. Results showed that higher dosage of PMS or g-C3N4 could increase the activation amount of PMS and corresponding DMP degradation efficiency, but the latter approach was more productive in terms of making the most of PMS. High DMP concentration hindered effective contact between PMS and g-C3N4, but could provide efficient use of PMS. Higher DMP degradation efficiency was achieved at pH lower than the point of zero charge (5.4). Based on intermediates identification, the DMP degradation was found mainly through radical attack (·OH and SO4·-) of the benzene ring and oxidation of the aliphatic chains.

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Noble metal-like behavior of plasmonic Bi particles deposited on reduced TiO2 microspheres for efficient full solar spectrum photocatalytic oxygen evolution Hang Zhao, Zhangqian Liang, Xiang Liu, Pengyuan Qiu, Hongzhi Cui, Jian Tian 2020, 41 (2):  333-340.  DOI: 10.1016/S1872-2067(19)63428-5 Abstract ( 216 )   [Full Text(HTML)] () PDF (2383KB) ( 263 )   Supporting Information Herein, novel plasmonic Bi metal in situ deposited in reduced TiO2 microspheres (Bi@R-TiO2) are fabricated via a bimetallic MOF-derived synthesized strategy by adjusting the synthesizing temperature. Different characterization techniques, including XRD, SEM, TEM, XPS, DRS, PL, EIS, and photocurrent generation, are performed to investigate the structural and optical properties of the as-prepared samples. The results indicate that the Bi particles are generated inside and outside of reduced TiO2 microspheres via the reduction of Ti4+ and Bi3+ by ethylene glycol. When the annealing temperature is controlled at 300 ℃, the corresponding Bi@R-TiO2-300 sample with an appropriate amount of Bi nanoparticles exhibits the highest full solar spectrum photocatalytic oxygen evolution activity (4728.709 μmol h-1 g-1), which is 5.9 and 9.5 times higher than that of pure TiO2 and Bi-Ti bimetal organic frameworks (Bi-Ti-MOFs). Several reasons are suggested for the above results:(1) Bi metal behaves as an "electron acceptor" to accelerate the charge carrier transfer from TiO2 to Bi; (2) The surface plasmon resonance effect of loaded metallic Bi particles can enhance the visible and NIR light absorption capacity; (3) The generation of Ti3+ further narrows the band gap of TiO2.

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Exclusively catalytic oxidation of toluene to benzaldehyde in an O/W emulsion stabilized by hexadecylphosphate acid terminated mixed-oxide nanoparticles Changshun Deng, Mengxia Xu, Zhen Dong, Lei Li, Jinyue Yang, Xuefeng Guo, Luming Peng, Nianhua Xue, Yan Zhu, Weiping Ding 2020, 41 (2):  341-349.  DOI: 10.1016/S1872-2067(19)63417-0 Abstract ( 133 )   [Full Text(HTML)] () PDF (3233KB) ( 319 )   A series of hexadecylphosphate acid (HDPA) terminated mixed-oxide nanoparticles have been investigated to catalyze the oxidation of toluene exclusive to benzaldehyde under mild conditions in an emulsion of toluene/water with the catalysts as stabilizers. With the HDPA-Fe2O3/Al2O3 as the basic catalyst, a series of transition metals, such as Mn, Co, Ni, Cu, Cr, Mo, V, and Ti, was respectively doped to the basic catalyst to modify the performance of the catalytic system, in expectation of influencing the mobility of the lattice oxygen species in the oxide catalysts. Under normally working conditions of the catalytic system, the nanoparticles of catalysts located themselves at the interface between the oil and water phases, constituting the Pickering emulsion. Both the doped iron oxide and its surface adsorbed hexadecylphosphate molecules were essential to the catalytic system for excellent performances with high toluene conversions as well as the exclusive selectivity to benzaldehyde. Under optimal conditions,~83% of toluene conversion and >99% selectivity to benzaldehyde were obtained, using molecular oxygen as oxidant and HDPA-(Fe2O3-NiO)/Al2O3 as the catalyst. This process is green and low cost to produce high quality benzaldehyde from O2 oxidation of toluene.

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Promotion effects of nickel-doped Al2O3-nanosheet-supported Au catalysts for CO oxidation Rao Lu, Lei He, Yang Wang, Xin-Qian Gao, Wen-Cui Li 2020, 41 (2):  350-356.  DOI: 10.1016/S1872-2067(19)63439-X Abstract ( 153 )   [Full Text(HTML)] () PDF (2078KB) ( 322 )   Supporting Information Supported gold catalysts show high activity toward CO oxidation, and the nature of the support significantly affects the catalytic activity. Herein, serial Ni doping of thin porous Al2O3 nanosheets was performed via a precipitation-hydrothermal method by varying the amount of Ni during the precipitation step. The prepared nanosheets were subsequently used as supports for the deposition of Au nanoparticles (NPs). The obtained Au/NixAl catalysts were studied in the context of CO oxidation to determine the effect of Ni doping on the supports. Enhanced catalytic performances were obtained for the Au/NixAl catalysts compared with those of the Au supported on bare Al2O3. The Ni content and pretreatment atmosphere were both shown to influence the catalytic activity. Pretreatment under a reducing atmosphere was beneficial for improving catalytic activity. The highest activity was observed for the catalysts with a Ni/Al molar ratio of 0.05, achieving complete CO conversion at 20℃ with a gold loading of 1 wt%. The in-situ FTIR results showed that the introduction of Ni strengthened CO adsorption on the Au NPs. The H2-TPR and O2-TPD results indicated that the introduction of Ni produced new oxygen vacancies and allowed the oxygen molecules to be adsorbed and activated more easily. The improved catalytic performance after doping Ni was attributed to the smaller size of the Au NPs and more active oxygen species.

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Photocatalytic C-X borylation of aryl halides by hierarchical SiC nanowire-supported Pd nanoparticles Zhi-Feng Jiao, Ji-Xiao Zhao, Xiao-Ning Guo, Xiang-Yun Guo 2020, 41 (2):  357-363.  DOI: 10.1016/S1872-2067(19)63449-2 Abstract ( 87 )   [Full Text(HTML)] () PDF (1140KB) ( 275 )   Supporting Information Hierarchical SiC nanowire-supported Pd nanoparticles showed high photocatalytic activity for the C-X (X=Br, I) borylation of aryl halides at 30℃. The SiC/Pd Mott-Schottky contact enhances the rapid transfer of the photogenerated electrons from SiC to the Pd nanoparticles. As a result, the concentrated energetic electrons in the Pd nanoparticles can facilitate the cleavage of C-I or C-Br bonds, which normally requires high-temperature thermal processes. We show that the present Pd/SiC photocatalyst is capable of catalyzing the transformation of a large variety of aryl halides to their corresponding boronate esters under visible light irradiation, with excellent yields.

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Enhanced low-temperature NH3-SCR performance of CeTiOx catalyst via surface Mo modification Lulu Li, Peixiao Li, Wei Tan, Kaili Ma, Weixin Zou, Changjin Tang, Lin Dong 2020, 41 (2):  364-373.  DOI: 10.1016/S1872-2067(19)63437-6 Abstract ( 87 )   [Full Text(HTML)] () PDF (1022KB) ( 322 )   Supporting Information The effect of molybdenum oxide on the activity and durability of CeO2-TiO2 catalyst for NO reduction by NH3 was examined. It was found that the introduction of Mo could improve the low-temperature NH3-SCR activity and SO2/H2O durability of the CeO2-TiO2 catalyst and an optimal loading of Mo was 4 wt.%. The best MoO3/CeO2-TiO2 catalyst displayed over 90% NO conversion from 200℃ to 400℃ and obtained 4-fold increase in NO conversion compared to CeO2-TiO2 at 150℃. The characterization results revealed that the number of Brönsted acid sites over MoO3/CeO2-TiO2 was significantly increased, and the adsorption of nitrate species was dramatically weakened because of the coverage of MoO3, which were favorable for the high NH3-SCR performance. It is believed that the MoO3/CeO2-TiO2 catalyst is a suitable substitute for the NH3-SCR reaction.