Photocatalytic H₂ production on hybrid catalyst system composed of inorganic semiconductor and cobaloximes catalysts

• Published in: Journal of catalysis 2011-07, Vol.281 (2), p.318-324
• Main Authors: Wen, Fuyu, Yang, Jinhui, Zong, Xu, Ma, Baojun, Wang, Donge, Li, Can
• Format: Article
• Language: English
• Subjects: absorption; acetonitrile; adsorption; Catalysis; Catalysts; Chemical compounds; Chemistry; electron transfer; Electron transfer reactions; Exact sciences and technology; General and physical chemistry; hydrogen; hydrogen production; irradiation; photocatalysis; Photochemistry; photosystem I; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); semiconductors; sorption isotherms; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2011.05.015

An artificial photocatalytic system mimicking photosystem I (PSI) has been assembled using semiconductor (CdS) as photosensitizer, cobaloximes (Coᴵᴵᴵ complexes) as H₂ evolution catalysts, and triethanolamine (TEOA) as sacrificial electron donor. This artificial photocatalytic system shows high hydrogen evolution activity (turnover number up to 171 based on Coᴵᴵᴵ(dmgH)₂pyCl 1) under visible light irradiation. The apparent quantum efficiency (QE) for 1/CdS hybrid photocatalytic system in acetonitrile solution at 420nm is calculated to be 9.1%. The interfacial electron transfer from photoexcited CdS to Coᴵᴵᴵ complexes is very efficient through the weak adsorption of Coᴵᴵᴵ complexes on CdS. The adsorption of 1 on CdS in acetonitrile fits Langmuir equation, the maximum monolayer adsorption capacity is 3×10⁻³mmolg⁻¹, which means most of 1 are in the solution. The rate of hydrogen production exhibits a quadratic dependence on the total concentration of 1. Therefore, a bimetallic catalysis pathway is proposed. The efficient electron transfer, the broad electronic absorption character of CdS photosensitizer as well as the H₂ evolution ability of Coᴵᴵᴵ complexes, account for the high photocatalytic activity of this hybrid photocatalytic system.