Promising GeSe Nanosheet-Based Thin-Film Photocathode for Efficient and Stable Overall Solar Water Splitting

Compound semiconductor GeSe nanosheet based thin films were systematically researched for application in solar water splitting. P-type GeSe films obtained from the rapid thermal sublimation method have a sheet-like grain structure and a homogeneous elemental distribution, which is suitable for application in photocathodes for solar hydrogen production. Deposition of a CdS layer on top of GeSe was found to be effective in enhancing the photoelectrochemical properties due to the p-n junction formed at the interface of CdS/GeSe that enhances the separation rate of photoexcited carriers. Furthermore, the atomic layer deposition of the TiO2 overlayer under the CdS/GeSe photocathode not only protects the CdS from photocorrosion but also reduces surface recombination, which could generally enhance photocathode performance. The obtained Pt-TiO2/CdS/GeSe photocathode generated ~10.5 mA/cm2 under 0 VRHE and presented an onset potential of ~ 0.45 VRHE. The calculated half cell solar to hydrogen efficiency (HC-STH) o...