Fabrication of a Partial Encapsulation Architecture on S-Scheme Heterojunctions toward Durable Selective Photocatalytic CO2 Reduction

It remains a challenging issue to achieve durably stable photocatalytic CO₂ reduction over heterojunctions owing to their inherent structural assembly features. Herein, a unique partial encapsulation architecture is fabricated on the 3D/2D CoWO₄/C₃N₅ heterojunction by embedding CoWO₄ microspheres on C₃N₅ nanosheets, which achieves efficient, durable, stable, and selective photocatalytic CO₂ reduction. For the optimal 5%-CoWO₄/C₃N₅ heterojunction, the yield of selective CO₂ reduction to CO is 7.70 and 3.82 times higher than those of CoWO₄ and C₃N₅ in 4 h, respectively, and it maintains a stable CO generation rate within 20 cycles over 80 h. A series of characterization experiments and density functional theory calculations reveal that the structural stability is reinforced significantly via strong interfacial interaction owing to the unique partial encapsulation architecture fabricated on the 3D/2D CoWO₄/C₃N₅ heterojunction, the separation efficiency of photogenerated carriers is improved by inducing a built-in electric field and triggering the S-scheme charge-transport path, and the high CO product selectivity is attributed to the much lower free energy required for the generation path of CO compared to that for CH₄.