CsPbBr3/platinum and CsPbBr3/graphite hybrid photoelectrodes for carbon dioxide conversion to oxalic acid

CsPbBr3 halide perovskites have been recently received a lot of interest in the field of photo and electro catalysis, solar cells, and photodetectors due to their tunable band gap, large absorption coefficient and high carriers' mobility. However, CsPbBr3 poor water stability limits its real application and the development of related de-vices. In this work, hybrid CsPbBr3/platinum (Pt) and CsPbBr3/graphite (C) photo-electrodes are employed, for the first time, in aqueous environment for the photo-electrochemical CO2 conversion to liquid products. Hybrid photo-electrodes were prepared depositing CsPbBr3 by spin coating and sputtering Pt or C on top of it to obtain a homogeneous protective layer with the same thickness. Thanks to the Pt and C layers, the instability of the perovskite in water environment is overcome and the new hybrid electrodes obtained still showed the ability to absorb light in the visible region producing photocurrent. The as-obtained photo-electrodes demonstrated energy band values suitable to reduce carbon dioxide by photo-electrocatalytic reaction in water environment. As main results, these hybrid electrodes produced complex organic molecules such as oxalic acid with Faradic efficiencies close to 44% (at-0.8 V vs Ag/AgCl) using graphite in combination with CsPbBr3.