Recent progress on post-synthetic treatments of photoelectrodes for photoelectrochemical water splitting

For the global energy demand and climate change challenges, seeking renewable, sustainable energy sources is of great significance. Photoelectrochemical (PEC) water splitting is one of the promising technologies for converting intermittent solar energy into storable hydrogen energy, to tackle these issues. As the core component in a PEC system, photoelectrodes have been modified by various strategies including nanostructuring, facet-engineering, elemental doping, and heterostructured engineering. Apart from these techniques, numerous effective post-synthetic treatments have also been used to facilely and powerfully boost the physicochemical properties of photoelectrodes, for the enhancement of their PEC performance. Among them, a number of post-treatments can selectively influence photoelectrode surface and subsurface areas, altering surface states that play crucial roles in the hydrogen/oxygen evolution reaction. In virtue of such post-treatments, we summarize recently reported post-synthetic treatments for enhanced PEC applications. Post-treatment methods are classified into three sections: chemical treatments, electrochemical and irradiation-based treatments, and post-annealing treatments. In the end, a summary and outlook section regarding the utilization of post-treatments for PEC applications have been provided. This review can provide inspiration for further studies about post-treatments, not only in the PEC water splitting field, but also in other aspects, such as electrolysis.