The carbon dioxide (CO2) emission produced from fossil fuel combustion has been identified as a primary contributor to global warming. It is urgent to develop efficient methods for generating renewable and clean energy while eliminating CO2 emissions. Photoelectrochemical (PEC) water splitting is regarded as a promising strategy for converting intermittent sunlight into carbon-free hydrogen fuel. In PEC systems, semiconducting materials are employed as photoelectrodes, absorbing photons to generate electron-hole pairs, thereby driving the hydrogen reduction or oxygen oxidation reactions. Over the past few decades, various semiconducting materials have been reported for PEC water splitting, such as silicon (Si), cadmium telluride (CdTe), copper indium gallium selenide (CIGS), Cu-based chalcogenides, cuprous oxide (Cu2O), bismuth vanadate (BiVO4), and hematite (α-Fe2O3). Nonetheless, challenges such as the complex fabrication process of Si, the scarcity of In and Te, the toxicity of Cd, and the poor stability of Cu2O for the abovementioned materials have severely restricted large-scale commercialization. The development of high-efficiency, low-cost, and stable semiconducting materials used in PEC systems plays a crucial role in meeting the entire society's energy demand.