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Chinese Journal of Catalysis
2019, Vol. 40, No. 8
Online: 18 August 2019

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Cover: Thermally catalytic degradation of organic pollutants under dark ambient conditions provides unparalleled advantages over other advanced oxidation processes (AOPs) in treating domestic and industrial contaminated wastewaters in terms of energy conservation and easy operation, and renders promising applications in the field of environmental remediation. Read more about the article behind the cover on pages 1117-1134.

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Table of Contents for VOL.40 No.8 2019, 40 (8):  0-0.  Abstract ( 35 )   PDF (2491KB) ( 178 )

Review

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Thermal catalysis under dark ambient conditions in environmental remediation: Fundamental principles, development, and challenges Huihuang Chen, Jiangang Ku, Lianzhou Wang 2019, 40 (8):  1117-1134.  DOI: 10.1016/S1872-2067(19)63366-8 Abstract ( 197 )   [Full Text(HTML)] () PDF (2799KB) ( 631 )   Thermal catalytic degradation of organic pollutants conducted in the dark at room temperature under atmospheric pressure without the need of external chemicals and energy sources has attracted a lot of attention over the last two decades. It provides unparalleled advantages over other advanced oxidation processes (AOPs) in treating domestic and industrial contaminated wastewater from the viewpoint of energy/chemical conservation and ease of operation. Rich knowledge has been accumulated in terms of the synthesis and application of thermal catalysts though controversies remain regarding their underlying mechanisms. This review sheds light on the proposed thermo-catalysis mechanism for the first time and presents the development of thermal catalysts under dark ambient conditions with a focus on catalyst materials, catalytic activity, and mechanism. The present review aims to provide mechanistic insights into the rational design of novel and efficient catalysts, and their underlying mechanisms as well as the emerging challenges and perspectives in thermo-catalysis under dark ambient conditions used for the practical and efficient treatment of contaminated wastewater.

Communication

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Brönsted acidic ionic liquid catalyzed synthesis of benzo[a]carbazole from renewable acetol and 2-phenylindoles in a biphasic system Minghao Li, Fengtian Wu, Yanlong Gu 2019, 40 (8):  1135-1140.  DOI: 10.1016/S1872-2067(19)63370-X Abstract ( 116 )   [Full Text(HTML)] () PDF (745KB) ( 303 )   An efficient metal-free strategy for the synthesis of pharmaceutically relevant benzo[a]carbazoles from the derivatives of readily available 2-phenylindole and bio-renewable acetol in an aqueous biphasic system was developed. This protocol employed a sulfone-containing Brönsted acidic ionic liquid as the catalyst, which could be used for five times without a noticeable decrease in its activity and selectivity. Various substituted 2-phenylindoles and α-hydroxyketones participated in the reaction smoothly, with water as the sole byproduct. Mechanistically, the reaction involved the conventional carbon-nucleophile-induced Heyns-type rearrangement and downstream intramolecular olefination.

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Amine formylation with CO2 and H2 catalyzed by heterogeneous Pd/PAL catalyst Xingchao Dai, Bin Wang, Aiqin Wang, Feng Shi 2019, 40 (8):  1141-1146.  DOI: 10.1016/S1872-2067(19)63397-8 Abstract ( 164 )   [Full Text(HTML)] () PDF (866KB) ( 379 )   For the first time, Pd supported on natural palygorskite was developed for amine formylation with CO2 and H2. Both secondary and primary amines with diverse structures could be converted into the desired formamides at < 100℃, and good to excellent yields were obtained.

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Laser-direct-writing of 3D self-supported NiS2/MoS2 heterostructures as an efficient electrocatalyst for hydrogen evolution reaction in alkaline and neutral electrolytes Peng-Fei Cheng, Ting Feng, Zi-Wei Liu, De-Yao Wu, Jing Yang 2019, 40 (8):  1147-1152.  DOI: 10.1016/S1872-2067(19)63390-5 Abstract ( 79 )   [Full Text(HTML)] () PDF (2527KB) ( 411 )   Searching for low-cost widely applicable electrocatalysts for hydrogen production is very important. Here, 3D self-supported NiS2/MoS2 heterostructures were synthesized via a one-step millisecond-laser-direct-writing method; these structures exhibited excellent hydrogen evolution reaction activities over a wide pH range. The current density of 10 mA cm-2 could be reached at low overpotentials of 98 and 159 mV in alkaline and neutral electrolytes, respectively. Such an outstanding electrocatalytic performance should be attributed to the integration of the 3D self-supported nanostructures, the high conductivity of the framework, and particularly, the incalculable heterointerfaces formed between NiS2 and MoS2. This work provides a new strategy to study interfacial engineering and the mechanism of interface enhancement.

Articles

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Silver-catalyzed carboxylative cyclization of alkynic hydrazones with carbon dioxide Wenzhen Zhang, Yuqian Sun, Min Zhang, Hui Zhou, Xiaobing Lu 2019, 40 (8):  1153-1159.  DOI: 10.1016/S1872-2067(19)63352-8 Abstract ( 98 )   [Full Text(HTML)] () PDF (783KB) ( 276 )   The development of new catalytic methodologies to synthesize heterocyclic fine chemicals using carbon dioxide as a synthon has attracted considerable attention. Herein, we report the silver(I)-catalyzed carboxylative cyclization of a variety of alkynic hydrazones with carbon dioxide to produce the corresponding 1,3,4-oxadiazin-2-ones under mild reaction conditions. In this reaction, silver(I) salts play a π-Lewis acid role for the highly efficient activation of the alkyne moiety in the hydrazone substrates. Single-crystal X-ray analysis and NOE experiments confirm that the newly formed oxadiazinone products exhibit Z configuration. Based on control experiments and NMR studies, a mechanism including the formation of a reactive carbazate intermediate, electrophilic cyclization, and subsequent protonation is proposed. This study offers an efficient and atom-economical method for the synthesis of biologically important 1,3,4-oxadiazin-2-ones.

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MoS2-rGO hybrid architecture as durable support for cathode catalyst in proton exchange membrane fuel cells Muhammad Tuoqeer Anwar, Xiaohui Yan, Muhammad Rehman Asghar, Naveed Husnain, Shuiyun Shen, Liuxuan Luo, Xiaojing Cheng, Guanghua Wei, Junliang Zhang 2019, 40 (8):  1160-1167.  DOI: 10.1016/S1872-2067(19)63365-6 Abstract ( 116 )   [Full Text(HTML)] () PDF (2100KB) ( 405 )   Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material.

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Highly efficient Nb2O5 catalyst for aldol condensation of biomass-derived carbonyl molecules to fuel precursors Yaxuan Jing, Yu Xin, Yong Guo, Xiaohui Liu, Yanqin Wang 2019, 40 (8):  1168-1177.  DOI: 10.1016/S1872-2067(19)63371-1 Abstract ( 182 )   [Full Text(HTML)] () PDF (840KB) ( 564 )   Aldol condensation is of significant importance for the production of fuel precursors from biomass-derived chemicals and has received increasing attention. Here we report a Nb2O5 catalyst with excellent activity and stability in the aldol condensation of biomass-derived carbonyl molecules. It is found that in the aldol condensation of furfural with 4-heptanone, Nb2O5 has obviously superior activity, which is not only better than that of other common solid acid catalysts (ZrO2 and Al2O3), more importantly, but also better than that of solid base catalysts (MgO, CaO, and magnesium-aluminum hydrotalcite). The detailed characterizations by N2 sorption/desorption, NH3-TPD, Py-FTIR and DRIFTS study of acetone adsorption reveal that Nb2O5 has a strong ability to activate the C=O bond in carbonyl molecules, which helps to generate a metal enolate intermediate and undergo the nucleophilic addition to form a new C-C bond. Furthermore, the applicability of Nb2O5 to aldol condensation is extended to other biomass-derived carbonyl molecules and high yields of target fuel precursors are obtained. Finally, a multifunctional Pd/Nb2O5 catalyst is prepared and successfully used in the one-pot synthesis of liquid alkanes from biomass-derived carbonyl molecules by combining the aldol condensation with the sequential hydrodeoxygenation.

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Promotion of activation ability of N vacancies to N2 molecules on sulfur-doped graphitic carbon nitride with outstanding photocatalytic nitrogen fixation ability Zheng Li, Guizhou Gu, Shaozheng Hu, Xiong Zou, Guang Wu 2019, 40 (8):  1178-1186.  DOI: 10.1016/S1872-2067(19)63364-4 Abstract ( 159 )   [Full Text(HTML)] () PDF (1634KB) ( 378 )   Nitrogen vacancies and sulfur co-doped g-C3N4 with outstanding N2 photofixation ability was synthesized via dielectric barrier discharge plasma treatment. X-ray diffraction, ultraviolet-visible spectroscopy, N2 adsorption, scanning electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and temperature-programmed desorption were used to characterize the as-prepared catalyst. The results showed that plasma treatment cannot change the morphology of the as-prepared catalyst but introduces nitrogen vacancies and sulfur into g-C3N4 lattice simultaneously. The as-prepared co-doped g-C3N4 displays an ammonium ion production rate as high as 6.2 mg·L-1·h-1·gcat-1, which is 2.3 and 25.8 times higher than that of individual N-vacancy-doped g-C3N4 and neat g-C3N4, respectively, as well as showing good catalytic stability. Experimental and density functional theory calculation results indicate that, compared with individual N vacancy doping, the introduction of sulfur can promote the activation ability of N vacancies to N2 molecules, leading to promoted N2 photofixation performance.

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Decorating Ag/AgCl on UiO-66-NH2: Synergy between Ag plasmons and heterostructure for the realization of efficient visible light photocatalysis Wanyue Zhao, Tong Ding, Yating Wang, Moqing Wu, Wenfeng Jin, Ye Tian, Xingang Li 2019, 40 (8):  1187-1197.  DOI: 10.1016/S1872-2067(19)63377-2 Abstract ( 141 )   [Full Text(HTML)] () PDF (1392KB) ( 435 )   UiO-66-NH2, as typical visible light responsive Zr-based metal-organic frameworks (MOFs), has attracted great interest in recent years. However, rapid combination of the photoinduced carriers limits its further application. Here, we designed a facile precipitation-photoreduction method to post-synthetically decorate Ag/AgCl on the surface of UiO-66-NH2 and form a heterostructure. Metallic Ag can not only transmit electrons between UiO-66-NH2 and AgCl but also absorb visible light, because of the surface plasmon resonance (SPR) effect. The rhodamine B photodegradation rate of UiO-66-NH2/Ag/AgCl (16.2 wt.% Ag) is about 10 and 4 times those of UiO-66-NH2 and Ag/AgCl, respectively. The SPR effect of Ag NPs and the formation of a heterostructure synergistically increase the absorbability of visible light, accelerate the separation of photoinduced charges, and promote the formation of superoxide radicals. We expect that our work could provide a new viewpoint for constructing efficient MOF-based photocatalytic systems.

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Immobilization of metal-organic molecular cage on g-C3N4 semiconductor for enhancement of photocatalytic H2 generation Yuanpu Wang, Liang Liu, DongJun Wu, Jing Guo, Jianying Shi, Junmin Liu, Chengyong Su 2019, 40 (8):  1198-1204.  DOI: 10.1016/S1872-2067(19)63387-5 Abstract ( 98 )   [Full Text(HTML)] () PDF (1459KB) ( 479 )   A new compound based on immobilizing of Pd6(RuL3)8(BF4)28 (L=2-(pyridin-3-yl)-1H-imidazo[4,5-f] [1,10]-phenanthroline) cage (MOC-16) on g-C3N4 was synthesized. Infrared spectrum and powder X-ray diffraction were used to characterize structure of hybrid MOC-16/g-C3N4, as well as UV-vis absorption spectrum and X-ray photoelectron spectroscopy were carried out to unveil photocatalytic mechanism. With the introduction of MOC-16, the absorption edge of MOC-16/g-C3N4 in UV-vis spectrum extended apparently to long-wavelength region compared with pristine g-C3N4. H2 evolution yielded with MOC-16/g-C3N4 in aqueous solution containing TEOA was much higher than that with RuL3/g-C3N4, Pd/RuL3/g-C3N4 and mixture of MOC-16 and g-C3N4, showing that the octahedral cage structure with high-efficient electron transfer and the interface interaction between MOC-16 and g-C3N4 were significant for improvement of H2 evolution.

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Cobalt/iron bimetal-organic frameworks as efficient electrocatalysts for the oxygen evolution reaction Shili Xie, Fei Li, Suxian Xu, Jiayuan Li, Wei Zeng 2019, 40 (8):  1205-1211.  DOI: 10.1016/S1872-2067(19)63384-X Abstract ( 256 )   [Full Text(HTML)] () PDF (1597KB) ( 557 )   The development of high efficiency and stable electrocatalysts for oxygen evolution is critical for energy storage and conversion systems. Herein, a series of Co/Fe bimetal-organic frameworks (MOFs) were fabricated using a facile ultrasonic method at room temperature, as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solution. The Co2Fe-MOF exhibited an overpotential of 280 mV at a current density of 10 mA cm-2, a low Tafel slope of 44.7 mV dec-1, and long-term stability over 12000 s in 1 mol L-1 KOH. This impressive performance was attributed to the high charge transfer rate, large specific surface area, and synergistic effects of the cobalt and iron centers.

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Novel SiO2 nanoparticle-decorated BiOCl nanosheets exhibiting high photocatalytic performances for the removal of organic pollutants Changlin Yu, Hongbo He, Xingqiang Liu, Julan Zeng, Zhen Liu 2019, 40 (8):  1212-1221.  DOI: 10.1016/S1872-2067(19)63359-0 Abstract ( 46 )   [Full Text(HTML)] () PDF (2237KB) ( 439 )   Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized by various techniques such as XRD, FT-IR, SEM/TEM, BET, UV-vis, DRS, XPS, and photocurrent measurements. The SiO2/BiOCl composite nanosheets displayed high photocatalytic activity and excellent stability in the degradation of organic pollutants such as phenol, bisphenol A (BPA), and rhodamine B (RhB). With respect to those over bare BiOCl, the degradation rates of RhB, BPA, and phenol over 1.88% SiO2/BiOCl increased 16.5%, 29.0%, and 38.7%, respectively. Radical capturing results suggested that h+ is the major reactive species and that hydroxyl (·OH) and superoxide (·O2-) radicals could also be involved in the degradation of organic pollutants. The enhanced photocatalytic performances of SiO2/BiOCl composites can be mainly attributed to the improved texture and the formation of intimate SiO2/BiOCl interfaces, which largely promoted the adsorption of organic pollutants, enhanced the light harvesting, and accelerated the separation of e- and h+.

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Photoelectrocatalytic CO2 reduction based on metalloporphyrin-modified TiO2 photocathode Yapeng Dong, Rong Nie, Jixian Wang, Xiaogang Yu, Pengcheng Tu, Jiazang Chen, Huanwang Jing 2019, 40 (8):  1222-1230.  DOI: 10.1016/S1872-2067(19)63375-9 Abstract ( 175 )   [Full Text(HTML)] () PDF (2237KB) ( 432 )   The conversion of CO2 and water to value-added chemicals under sunlight irradiation, especially by photoelectrocatalytic reduction process, is always a dream for human beings. A new artificial photosynthesis system composed of a metalloporphyrin-functionalized TiO2 photocathode and BiVO4 photoanode can efficiently transform CO2 and water to methanol, which is accompanied by oxygen release. This photoelectrocatalytic system smoothly produces methanol at a rate of 55.5 μM h-1 cm-2, with 0.6 V being the membrane voltage in plants. The production of hydrogen can also be observed when the voltage is more than 0.75 V, due to photocatalysis. Our results evidently indicate that the molecules of metalloporphyrin attached onto the surface of anatase (TiO2) behave as chlorophyll, NADP, and Calvin cycle in plant cells.