Synergistic integration of intrinsic polarization and heterojunction interface for enhanced photocatalytic CO2 reduction

A Synergistic strategy that integrates the intrinsic polarization field with heterojunction interfacial engineering is demonstrated for boosting photocatalytic CO 2 reduction. In the engineered Bi 4 O 5 Br 2 /Nb 2 O 5 heterojunction, a structure has not been previously reported for CO 2 photoreduction to date, the intrinsic polarization field of Bi 4 O 5 Br 2 facilitates initial charge separation within the bulk phase. The type-ii interfacial field drives the transfer of separated electrons toNb 2 O 5 , achieving effective spatial separation of carriers. This efficient charge separation promotes surface reactions, as evidenced by in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), which reveals accelerated formation and transformation of key intermediates (*CO 2 , *COOH and *CHO) along the reaction pathways toward CO and CH 4 . Using ultrapure water as the proton source, the CO and CH 4 production rates of the optimal composite reach 4.6 and 3.7 μmol g −1  h −1 , respectively, which are 2.0 and 4.6 times higher than those of pristine Bi 4 O 5 Br 2 . In contrast to conventional heterojunction strategies that focus solely on interfacial band engineering, this work simultaneously leverages the intrinsic properties of bulk materials, offering a new design paradigm for efficient CO 2 photoreduction.