Ligand-Induced Built-In Electric Field Amplification for Selective Photoelectrochemical Glycerol Valorization

Abstract

Selective photoelectrocatalytic glycerol oxidation to value-added chemicals offers a pivotal route for biomass refining and renewable energy conversion, yet it is severely constrained by sluggish charge transfer kinetics and intricate multi-step reaction pathways. Herein, we report a bromine-functionalized ligand engineering strategy to modulate the local coordination environment of metal-organic frameworks (MOFs), simultaneously improving interfacial charge kinetics and surface reaction dynamics. The strong electron-withdrawing effect of bromine elevates the heterojunction work function, intensifying the interfacial built-in electric field (BIEF), which boosts charge separation efficiency to 89.6% and prolongs carrier lifetime by approximately fourfold. Consequently, the resulting Ni-MOF(Br)/BVO photoanode achieves a productivity of 348.2 mmol m−2 h−1 and a Faradaic efficiency of 85.8% for glycerol oxidation. Detailed mechanistic investigations, combining in situ spectroscopy and theoretical calculations, reveal that Br functionalization optimizes the electronic structure of Ni active centers, strengthening glycerol adsorption via its middle hydroxyl and thereby steering the reaction selectively toward C−C bond-retentive C3 products, particularly dihydroxyacetone. This work establishes a mechanistic framework for synergistically enhancing charge dynamics and reaction selectivity via ligand engineering.