Tunable syngas production from photocatalytic CO(2) reduction with mitigated charge recombination driven by spatially separated cocatalysts

Photocatalytic CO(2) reduction represents a sustainable route to generate syngas (the mixture of CO and H(2)), which is a key feedstock to produce liquid fuels in industry. Yet this reaction typically suffers from two limitations: unsuitable CO/H(2) ratio and serious charge recombination. This paper describes the production of syngas from photocatalytic CO(2) reduction with a tunable CO/H(2) ratio via adjustment of the components and surface structure of CuPt alloys and construction of a TiO(2) mesoporous hollow sphere with spatially separated cocatalysts to promote charge separation. Unlike previously reported cocatalyst-separated hollow structures, we firstly create a reductive outer surface that is suitable for the CO(2) reduction reaction. A high evolution rate of 84.2 μmol h(–1) g(–1) for CO and a desirable CO/H(2) ratio of 1 : 2 are achieved. The overall solar energy conversion yield is 0.108%, which is higher than those of traditional oxide and sulfide based catalysts (generally about 0.006–0.042%). Finally, density functional theory calculations and kinetic experiments by replacing H(2)O with D(2)O reveal that the enhanced activity is mainly determined by the reduction energy of CO* and can be affected by the stability of COOH*.