Dual Vacancy Engineering in Alloyed Ga‐Zn‐Cu‐Se Quantum Dots for Photocatalytic 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran Conversion

Abstract

Abstract Highly ‐active/‐selective photocatalytic biomass conversion is of great importance for achieving remarkable solar‐to‐chemical conversion. However, serious challenges, e.g., limited photon utilization, high charge recombination, and sluggish/uncontrolled reaction kinetics, remain for further development in this area. Herein, a dual‐vacancy‐engineering strategy is employed to regulate the Ga‐Zn co‐doped Ga‐Zn‐Cu‐Se (GZC) quantum dots (QDs) by a cation exchange route utilizing the CuSe template. The optimized GZC QDs exhibit excellent photocatalytic performances for the selective oxidation of 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF), with 89% HMF conversion and 91% DFF selectivity. Advanced ex situ/in situ characterizations, together with theoretical calculations, reveal the origins of the excellent performance: i) Zn doping enhances charge carrier mobility, thereby promoting the HMF‐to‐DFF conversion rate; ii) Ga doping introduces intermediate states in electronic structure, facilitating better charge separation/transfer; iii) Ga/Zn co‐introduction results in formation of Se/Cu vacancies, which play a critical role in charge separation and reactive oxygen species generation. Overall, the research exhibits a rational strategy for designing vacancy‐engineered photocatalysts, offering a promising approach for selective biomass conversion.