Strongly affected photocatalytic CO2 reduction by CO2 adsorbed to the surface of Ba2(In1.8Cr0.2)O5·(H2O) powders

Nanocrystalline Ba2(In1.8Cr0.2)O5·(H2O)δ powders were synthesized via a polymerizable-complex method in two different ways, one based on citric acid and the other additionally on 2,6-pyridinedicarboxylic acid, 2,6-diaminopyridine, and polyethylene glycol. Crystal structure, surface area, thermochemical and optical properties were analyzed. The photocatalytic activity was measured by the reduction of CO2 under H2 gas flow. CO2 adsorption at the catalyst surface is found to be a critical factor strongly affecting the reactivity. With this study, we demonstrate the importance of the surface states as a crucial parameter when developing better CO2 photo-reduction catalysts