Engineered S-Scheme Heterojunction for Efficient CO₂ Photoreduction on Bismuth Oxybromide

Artificial photosynthesis presents a highly promising approach for addressing global energy and environmental challenges. However, its efficiency remains constrained by rapid charge recombination and inefficient CO₂ activation. To overcome these limitations, cobalt-nickel layered double hydroxide (CN-LDH) is decorated onto BiOBr nanosheets to enhance Lewis alkaline sites and facilitate charge separation. The resultant composite, denoted as B_xC_y, exhibits a stronger internal electric field than its individual components, promoting efficient migration of photogenerated carriers. This engineered structure directs photoinduced electrons accumulated in CN-LDH for CO₂ reduction, as verified by in situ Kelvin probe force microscopy. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy combined with pulsed chemisorption studies identifies the critical activated carbonate intermediates (*CO^2- and *COOH) as essential precursors for CO production. Consequently, the optimized B₅C₁ catalyst achieves a remarkable CO evolution rate of 88.92 μmol g^-1 with 100% selectivity. This work provides pivotal insights into the charge transfer dynamics and intermediate evolution pathways during photocatalytic CO₂ reduction.