Titanium Nitride Protected Cuprous Oxide Photocathode for Stable and Efficient Water Reduction

Photoelectrochemical water splitting for hydrogen production provides a pollution-free and sustainable way to alleviate the over-reliance on fossil fuels. Cu2O is one of the photocathodes most concerned with superior performance, but it suffers from photocorrosion in the electrolyte, which is unfavorable to hydrogen production. Therefore, a reasonable and simple protection strategy to inhibit the photocorrosion of Cu2O is urgently needed in the long term hydrogen production device. In this work, we proposed a Cu2O-based photocathode protection strategy, which uses atomic layer deposition technology to deposit TiN thin film as the protective layer. The optimized photocathode shows remarkably improved stability: the photocurrent density maintains the initial value of −1.4 mA cm–2 for more than 35 min at 0 V vs RHE; after 1-h testing, it still remains at 71% of the initial value, with 16-fold enhancement in comparison with that of the bare photocathode. This work offers a way to solve the stability issue of unstable photoelectrodes.