Surface Engineering of Nanomaterials for Photo-Electrochemical Water Splitting.

Photo-electrochemical water splitting represents a green and environmentally friendly method for producing solar hydrogen. Semiconductor nanomaterials with a highly accessible surface area, reduced charge migration distance, and tunable optical and electronic property are regarded as promising electrode materials to carry out this solar-to-hydrogen process. Since most of the photo-electrochemical reactions take place on the electrode surface or near-surface region, rational engineering of the surface structures, physical properties, and chemical nature of photoelectrode materials could fundamentally change their performance. Here, the recent advances in surface engineering methods, including the modification of the nanomaterial surface morphology, crystal facet, defect and doping concentrations, as well as the deposition of a functional overlayer of sensitizers, plasmonic metallic structures, and protective and catalytic materials are highlighted. Each surface engineering method and how it affects the structural features and photo-electrochemical performance of nanomaterials are reviewed and compared. Finally, the current challenges and the opportunities in the field are discussed.