Recent Advances of Photocatalytic Hydrogen Evolution via Water Vapor Splitting

Abstract Artificial photosynthesis, converting solar energy into hydrogen energy, holds an indispensable role to achieve carbon neutrality and sustainable development. Nevertheless, the hydrogen evolution reaction in liquid/solid/gas triphase systems is constrained by limitations such as insufficient light absorption, mass transfer resistance, inverse reactions, and side reactions. These factors collectively inhibit the achievement of a solar‐to‐hydrogen efficiency exceeding 10%, thereby hindering the potential industrial applications. The development of gas/solid biphase systems capable of directly splitting water vapor into hydrogen represents a promising strategy to address these challenges. Significant progress has been achieved in this field recently, yet a comprehensive and systematic review remains lacking. This review describes the basic mechanism of photocatalytic water vapor splitting and the cutting‐edge progress and various applications in this field, discussing the organization of various water vapor production methods that drive these processes. Furthermore, strategies for enhancing photocatalytic efficiency are proposed, focusing on both improving water vapor generation efficiency and designing highly effective photocatalysts. This review provides theoretical guidance needed for the future development of photocatalytic water vapor splitting, thereby contributing to the establishment of a sustainable and environmentally friendly energy‐conversion system.