Substrate-dependent ALD of Cux on TiO2 and its performance in photocatalytic CO2 reduction

Atomic layer deposition (ALD) technique has been proved to be an efficient method to synthesize or modify catalyst. In this study, Cu was loaded on different TiO 2 substrates, pristine TiO 2 and black TiO 2 (denoted as H-TiO 2 ) to achieve better CO 2 photocatalytic reduction performance. Both TiO 2 @Cu and H-TiO 2 @Cu exhibited dramatic enhancement for CO and CH 4 production. The peculiar phenomenon of TiO 2 outperforming H-TiO 2 after ALD loading was further studied by a series of characterization methods. Even though H-TiO 2 showed superior performance for photocatalytic CO 2 reduction than TiO 2 , pristine TiO 2 loaded with more Cu 0/+ after ALD deposition surpassed the performance of H-TiO 2 @Cu which possessed less amount of Cu 0/+ and more Cu 2+ . Cu 0/+ is proved to be the crucial factor for CO 2 reduction and it is capable of overshadowing the influence of Ti 3+ and V o . These results indicate that not only will ALD technique significantly enhance the CO 2 reduction performance after Cu deposition, but the substrate employed for loading and the chemical state of loaded material will also influence the subsequent catalytic performance. In addition, our result provides additional experiment evidence for justifying the significance of Cu 0/+ in photocatalytic CO 2 reduction reaction.