image: Scheme of the triphase photocatalytic system and mechanism of the triphase photocatalysis. CO2 can pump into liquid phase through hydrophobic surface and be closely adsorbed on the photocatalyst surface. The enrichment of CO2 on the catalyst surface would be responsible for the superior CRR performance and lower HER activity. view more
Credit: Chinese Journal of Catalysis
Photocatalytic CO2 reduction reaction (CRR) is recognized to be an ultimate strategy to convert CO2 into hydrocarbon fuels or organic raw materials so as to solve energy and environmental issues. However, the low concentration and slow diffusion rate of CO2 in liquid phase seriously restrict CRR efficiency. In addition, hydrogen evolution reaction (HER) generally exists as a competitive reaction in liquid phase, owing to the existence of a large amount of H2O on catalyst surface, eventually resulting in low activity and selectivity of CRR.
Hydrophobic substrate in contact with liquid phase that creates a unique triphase air-liquid-solid joint contact interfaces has been extensively studied since the 1990s and widely used in various fields, such as fuel cells, photocatalysis and electrocatalysis. This unique interfacial architecture allows reactant gas to reach the reaction interfaces and adsorb on the catalyst surface, significantly enhancing reaction rates of many gas-involved reactions. Compared to traditional diphase solid-liquid system in which gas transport is often the constraint condition, the introduction of hydrophobic surface can well solve this problem.
Recently, a research team led by Prof. Shaowen Cao from Wuhan University of Technology, China designed a triphase air-liquid-solid photocatalytic system through melamine?involved chemical vapor deposition on carbon paper. The as-obtained samples with a hydrophobic surface show wonderful improvement on CRR efficiency and obvious suppression on HER with a selectivity of 78.6%, as compared to the samples with a hydrophilic surface. Remarkably, the employment of phosphate environment can also dramatically boost photocatalytic activity in triphase system with a total CO2 photoreduction rate of 1175.5 μmol h-1 m-2, which is 8.8 times higher than that of water environment, and a selectivity of 93.8%. In brief, the enhancement on CRR activity and selectivity could be attributed to the much better CO2 transport and adsorption capability, both of which originate from the hydrophobic surface and the establishment of triphase air-liquid-solid joint interfaces, as well as the ability of phosphate to consume photogenerated holes. The results were published in Chinese Journal of Catalysis.
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About the Journal
Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 8.271. The Editors-in-Chief are Profs. Can Li and Tao Zhang. At Elsevier http://www.journals.elsevier.com/chinese-journal-of-catalysis Manuscript submission https://mc03.manuscriptcentral.com/cjcatal
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Chinese Journal of Catalysis