Construction mechanisms, synthesis strategies, and photocatalytic applications of homojunction catalysts: A review

With the increasing global concern for environmental issues and sustainable development, photocatalytic technology has significant promise in addressing environmental contamination and energy shortages. This technology utilizes renewable solar energy as an energy source and produces no harmful by-products. Notably, selecting suitable photocatalysts is the key to achieving efficient photocatalysis. Homojunction photocatalysts, consisting of elements with the same semiconductor material but different crystalline phases/exposed surfaces/dimensions, have garnered significant interest recently. The reason is that near-perfect lattice matching at the homojunction interface and continuous band bonding greatly facilitate photogenerated charge transport. Furthermore, the internal electric field in the homojunction well drives the migration and separation of photoinduced charge carriers, improving photocatalytic activity. Herein, this review summarizes the recent advances in homojunction photocatalysis, introduces the fundamentals of different homojunction photocatalysts, and focuses on the preparation methods of homojunction photocatalysts and their photocatalytic applications in energy production and environmental protection, such as reducing CO₂, producing H₂, fixing N₂, and degrading pollutants.