A BOB/CN-LDH system with an intimate interface is constructed, featuring a distinct built-in electric field directed from CN-LDH to BOB. Upon photoexcitation, electrons directionally migrate from BOB to CN-LDH, facilitating charge separation and thereby enhancing the artificial photosynthetic performance.

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 (*CO²⁻ 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.