Photocatalytic CO₂ Reduction with 100% CO Selectivity Using In₂O₃/CuO/g-C₃N₄ Ternary Composites

The key challenge in photocatalytic CO₂ reduction is to develop photocatalysts with high performance and ultrastability. Graphitic carbon nitride (g-C₃N₄) is a promising semiconductor photocatalyst due to its low cost, simple preparation, and stability. However, bulk g-C₃N₄ exhibits limitations such as low specific surface area, limited visible light absorption, and rapid recombination of photogenerated electron-hole pairs. Coupling multiple semiconductors enhances electron-hole separation, prolongs carrier lifetime, and improves interfacial charge transfer efficiency. Here, In₂O₃/CuO/g-C₃N₄ ternary composites are synthesized via thermal polymerization and characterized by using XRD, TEM, XPS, and UV-vis spectroscopy. The ternary composite achieves superior photogenerated carrier separation compared with In₂O₃/g-C₃N₄ and CuO/g-C₃N₄ binary composites. In photocatalytic CO₂ reduction tests, In₂O₃/CuO/g-C₃N₄ demonstrates higher catalytic activity with a CO yield of 890.50 μmol/g/h and a 100% CO selectivity.