Two-Dimensional Direct Z -Scheme Heterojunction Photocatalysts for Highly Efficient Energy Conversion and Chemical Synthesis

Photocatalysis offers a green and sustainable pathway to address the energy crisis and environmental pollution. Since single semiconductor materials often struggle to simultaneously achieve a broad light absorption range and strong redox ability, constructing heterojunctions is widely regarded as an effective strategy to enhance photocatalytic performance. Traditional Type-I, Type-II, and Type-III heterojunctions suffer from inherent limitations─such as significantly reduced redox ability due to carrier spatial confinement, insufficient redox potential, and band discontinuities that hinder charge separation. In contrast, two-dimensional (2D) direct Z-scheme heterojunctions effectively overcome these challenges by utilizing built-in electric fields to drive directional interfacial charge transfer, thereby achieving efficient carrier separation and strong redox ability, and demonstrating remarkable potential in photocatalytic H₂ production, CO₂ reduction, nitrogen fixation, and H₂O₂ synthesis. This review first systematically highlights the unique structural advantages of 2D direct Z-scheme heterojunctions and, through a combination of bibliometric analysis and representative literature, elucidates their development trends and key research directions. Second, we elaborate in detail on the core mechanisms, summarize the required potentials for different redox reactions, and discuss their applications in the four major photocatalytic fields mentioned, along with relevant construction and optimization strategies. Further, the role of nonadiabatic molecular dynamics simulations in analyzing ultrafast charge transfer dynamics is explored, while the potential of combining machine learning with high-throughput computing to accelerate material screening and design is also elaborated. Finally, we summarize the current challenges and propose potential directions for future development. This Perspective aims to provide a systematic reference framework and design guidance for the theoretical research and practical application of 2D direct Z-scheme heterojunctions, thereby promoting their further development in the field of efficient solar energy conversion and green synthesis.