The development of balanced heterojunction photocatalysts

Heterojunction photocatalysts have attracted tremendous attention because of their great potential for addressing worldwide energy and environmental issues. In the evolution of heterojunction photocatalysts from bulk to atomic scale, thin-layered heterojunction photocatalysts exhibit better photocatalytic properties but at the cost of a weak built-in electric field and insufficient stability for long-term reaction. Therefore, the development of more advanced heterojunctions is fundamentally important. A heterojunction with thickness within the space charge region has been developed and is called a balanced heterojunction, where fine-tuning the thickness of the heterojunction photocatalyst within the space charge region promotes a balance between photo-to-energy conversion efficiency and recyclability. In this perspective, the fundamentals, preparation methods, and advancements of balanced heterojunctions will be comprehensively elucidated. Based on the proposed concept of solar plants, the scalability of balanced heterojunctions is highlighted. Finally, the application scope of balanced heterojunctions is also discussed, along with challenges and new directions for practical application.