Liquid-Metal-Induced Hydrogen Insertion in Photoelectrodes for Enhanced Photoelectrochemical Water Oxidation

Fast charge separation and transfer (CST) is essential for achieving efficient solar conversion processes. This CST process requires not only a strong driving force but also a sufficient charge carrier concentration, which is not easily achievable with traditional methods. Herein, we report a rapid hydrogenation method enabled by gallium-based liquid metals (GBLMs) to modify the prototypical WO3 photoelectrode to enhance the CST for a PEC process. Protons in solution are controllably embedded into the WO3 photoanode accompanied by electron injection due to the strong reduction capability of GBLMs. This process dramatically increases the carrier concentration of the WO3 photoanode, leading to improved charge separation and transfer. The hydrogenated WO3 photoanode exhibits over a 229% improvement in photocurrent density with long-term stability. The effectiveness of GBLMs treatment in accelerating the CST process is further proved using other more general semiconductor photoelectrodes, including Nb2O5 and TiO2.