Efficient Solar-Driven Water Splitting Enabled by CoMoWS Catalysts on Silicon Photocathodes.

The construction of multicomponent amorphous metal sulfide systems has emerged as a promising strategy for enhancing the catalytic performance toward the HER. In this study, an amorphous CoMoWS catalyst was synthesized via a rapid and scalable ultrasonic spray pyrolysis method. The resulting CoMoWS-Si photoelectrode exhibits a high photocurrent density of 30.1 mA cm^-2, a ABPE of 7.26%, and outstanding operational stability exceeding 500 h. XPS confirms strong Co/Mo/W electronic coupling that enhances electronic structure and surface chemical environment. EIS and time-resolved carrier dynamics measurements confirm significantly accelerated interfacial charge transfer and extended carrier lifetimes, thereby suppressing recombination losses and promoting overall reaction kinetics. Integrated with a commercial silicon solar cell in tandem, the device demonstrates 5.17% solar-to-hydrogen efficiency for unbiased water splitting, operating stably over 100 h with no performance decay. These results underscore the potential of amorphous multimetallic sulfide systems as efficient and durable photoelectrocatalysts for scalable solar hydrogen production.