Built‐in electric field and interfacial orbital coupling of Z‐scheme <scp>CPDs</scp> / <scp> Bi ₃ O ₄ Cl </scp> for boosted <scp> CO ₂ </scp> photoreduction

Abstract Photocatalytic CO 2 reduction faces many challenges including rapid charge recombination and inefficient charge transfer. We construct a 0D/2D Z ‐ scheme heterojunction of carbonized polymer dots and Bi 3 O 4 Cl nanosheets (CPDs/Bi 3 O 4 Cl). This structure enables efficient carrier separation while maintaining the strong redox potentials of both components. Without sacrificial agents, the 7 wt% CPDs/Bi 3 O 4 Cl composite achieves a CO production rate of 11.17 μmol g −1 ·h −1 , 2.9 times that of pure Bi 3 O 4 Cl. DFT calculations show interfacial charge redistribution generates an internal electric field, directing charge transfer, suppressing recombination, and enhancing CO 2 adsorption. The elongated C–O bonds and robust C 2 p ‐Bi 6 p orbital interactions directly evidence efficient CO 2 activation at the interface. These effects lower the energy barrier for *COOH formation from 1.32 to 0.78 eV, highlighting the role of carbon dots and interfacial orbital coupling in Z‐scheme photocatalysts for enhanced adsorption‐activation.