Intense Surface Electric Field Stemming From Supramolecular Functionalization for Accelerated Photocatalytic CO₂ Conversion

Abstract As a promising technology with both environmental and economic benefits, photocatalytic CO 2 conversion relies heavily on photo‐carrier transport properties. However, oxide photocatalysts often face a significant limitation due to their restricted carrier transport distances, typically below 100 nm. Here, a surface electric field regulation strategy is proposed that enhances carrier transport in metal oxide photocatalysts by integrating specific porphyrin supramolecular assemblies. Through spin‐coating, monoamine metal porphyrin assemblies are uniformly deposited on the BiVO 4 photocatalyst via van der Waals interactions. The electronic coupling between amine groups and Co atoms in adjacent porphyrin units generates unoccupied orbitals, which facilitate the accumulation of holes within the Co‐porphyrin supramolecular system. This coupling induces interfacial electron redistribution and charge density reorganization, creating an intense surface electric field on BiVO 4 with an intensity of 17.4 V m −1 . As a result, the mobility of photo‐carriers within BiVO 4 is significantly enhanced, extending the hole diffusion length from 46.7 to 232.9 nm and enabling more efficient charge extraction at the surface. This improvement results in a 7.3‐fold increase in the photocatalytic CO 2 reduction performance, achieving an external quantum efficiency of 1.86%. The proposed approach offers a generalizable method for enhancing photo‐carrier properties in photocatalytic systems.