Solution-Processed CuS Nanostructures for Solar Hydrogen Production.

CuS is a promising solar energy conversion material due to its suitable optical properties, high elemental earth abundance, and nontoxicity. In addition to the challenge of multiple stable secondary phases, the short minority carrier diffusion length poses an obstacle to its practical application. This work addresses the issue by synthesizing nanostructured CuS thin films, which enables increased charge carrier collection. A simple solution-processing method involving the preparation of CuCl and CuCl molecular inks in a thiol-amine solvent mixture followed by spin coating and low-temperature annealing was used to obtain phase-pure nanostructured (nanoplate and nanoparticle) CuS thin films. The photocathode based on the nanoplate CuS (FTO/Au/CuS/CdS/TiO/RuO ) reveals enhanced charge carrier collection and improved photoelectrochemical water-splitting performance compared to the photocathode based on the non-nanostructured CuS thin film reported previously. A photocurrent density of 3.0 mA cm at -0.2 versus a reversible hydrogen electrode ( ) with only 100 nm thickness of a nanoplate CuS layer and an onset potential of 0.43 were obtained. This work provides a simple, cost-effective, and high-throughput method to prepare phase-pure nanostructured CuS thin films for scalable solar hydrogen production.