Atomic-scale interface engineering in Bi/Bi2O3 heterojunctions for selective CO2 photoreduction to methanol.

The strategic engineering of an Ohmic junction at the Bi/Bi2O3 (BBO) interface is demonstrated to synergistically enhance photocatalytic CO2-to-methanol conversion through precisely modulated charge behavior and interfacial energy alignment. This metallic Bi-semiconductor Bi2O3 Ohmic junction with local surface plasmon resonance effect induces a robust built-in electric field that promotes the unidirectional electron transfer from Bi2O3 to Bi while suppressing charge recombination. Theoretical calculations and experimental evidence reveal that the interfacial Bi sites within the Ohmic junction predominantly facilitate CO2 adsorption and activation to form *COOH, whereas ensuing protonation steps are favored on metallic Bi sites on BBO Ohmic junction. Furthermore, the Ohmic junction enhances interfacial electron density and strengthens orbital hybridization between Bi 6p and O 2p orbitals, thereby reducing the activation energy of the rate-limiting *CO2 → *COOH step by 0.6 eV, enabling a CH3OH production rate of 610 μmol g-1 under light irradiation. The work deciphers the dual role of Ohmic junctions in simultaneously resolving bulk charge transport limitations and tailoring surface catalytic landscapes, establishing a universal paradigm for metal-semiconductor heterojunction photocatalyst design.