A Cu2O/Cu2S-ZnO/CdS tandem photoelectrochemical cell for self-driven solar water splitting

A self-driven tandem cell for overall water splitting composed of a p-Cu2O photocathode modified with a thin Cu2S layer connected to a n-ZnO/CdS nanowire photoanode is demonstrated. By calculating the absorbed photon flux, it is proved that the two photoelectrodes are well spectral-matched in the wavelength range of 300-800 nm. Compared with the bare Cu2O photocathode, the Cu2S modified Cu2O counterpart has a higher photocurrent and a more anodic turn-on voltage due to the improved light absorption and the reduced charge transfer resistance. The photoelectrochemical (PEC) properties of the Cu2O/Cu2S photocathode coupled to the ZnO/CdS photoanode were investigated to demonstrate the feasibility of unassisted solar water splitting. An apparent photocurrent was observed for the tandem cell at zero bias, corresponding to a photoconversion efficiency of 0.38%. Our results indicate the tandem PEC cells based on connected semiconductor electrodes made from earth abundant elements have promising application potential in overall solar water splitting. (C) 2016 Elsevier B.V. All rights reserved.