Vacancy-induced asymmetric coordination of single-atom bismuth for selective photoelectrochemical oxidation of glycerol to dihydroxyacetone

Abstract

Photoelectrochemical (PEC) conversion of organic substrates into value-added chemicals provides a promising strategy for their utilization. However, the low efficiency and poor selectivity of photoanodes limit the development of this strategy. Herein, we report the construction of a highly efficient WO₃ photoanode with N–Bi–O asymmetric coordination via single-atom engineering. The asymmetric coordination of Bi single atoms can generate electron trapping states and create built-in electric fields, accelerating carrier transfer and separation, thereby enhancing the selectivity for glycerol oxidation to dihydroxyacetone (DHA). Additionally, in situ spectroscopy and DFT calculations reveal that single-atom Bi sites activate glycerol molecules and stabilize carbon radicals, while O-vacancy-induced N–Bi–O coordination further promotes DHA desorption by lowering the energy barrier through charge redistribution. Due to the asymmetric coordination structure, an improved photocurrent density of 1.21 mA cm⁻² with a glycerol conversion rate of 118.2 mmol m⁻² h⁻¹ and a DHA selectivity of 71.3% at 1.2 V vs. RHE is achieved over the optimized Bi, N-WO₃ photoanode.