Photocatalytic Conversion of CO₂ to CO with a p–n Heterojunction Based on Core–Shell β-Ga₂O₃@CoGa₂O₄ Nanorods

Constructing a p–n heterojunction is an efficient strategy to mitigate the charge-carrier recombination in semiconductors, thereby enhancing photocatalytic activity. This study designed and fabricated core–shell structured p–n heterojunction photocatalyst β-Ga 2 O 3 @CoGa 2 O 4 nanorods, using an in situ self-template-etched chemical route. The experimental results revealed that CoGa 2 O 4 nanoparticles could be intimately grown on the surface of β-Ga 2 O 3 nanorods, and the thickness of the CoGa 2 O 4 shells could be easily adjusted by optimizing the Co/Ga ratio. Notably, when employed as a photocatalyst for the conversion of CO 2 with H 2 O, without requiring additional sacrificial reagents, β-Ga 2 O 3 @CoGa 2 O 4 nanorods showed improved photocatalytic activity for CO 2 reduction to CO with a yield of 21.1 μmol g –1 h –1 compared to isolated β-Ga 2 O 3 or CoGa 2 O 4 . The presence of a p–n heterojunction in β-Ga 2 O 3 @CoGa 2 O 4 nanorods promotes charge-carrier transportation and separation through the internal electric field caused by n-type β-Ga 2 O 3 and p-type CoGa 2 O 4 . Consequently, this results in enhanced photocatalytic CO 2 reduction activity during continuous operation. This study would offer a feasible method for achieving effective photocatalytic CO 2 conversion through the rational design of p–n heterojunctions at the nanoscale.