Reconciling Activity and Selectivity in Photocatalytic HMF Oxidation over PtCo/g-C3N4 via d-Band Center Engineering

Abstract

Selective photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) is limited by an inherent activity-selectivity trade-off, arising from a mismatch between rapid charge transfer and controlled intermediate desorption. Herein, we present a thermodynamic-kinetic dual-regulation strategy using PtCo alloy-modified g-C3N4, where d-band center engineering simultaneously tunes interfacial charge transfer and adsorption energetics. Co incorporation downshifts the Pt d-band center by 0.33 eV via orbital hybridization, increasing antibonding occupancy in Pt−ODFF interactions and facilitating intermediate desorption. Advanced spectroscopic analyses and DFT calculations reveal that interfacial Co−N and Pt−Co channels mediate electron transfer, suppressing excessive reactive oxygen species (ROS) and preventing over-oxidation. The optimal Pt0.25Co0.25/g-C3N4 achieves 91.7% HMF conversion with 90% DFF selectivity under visible-light irradiation at ambient temperature. This work establishes d-band center engineering as a generalizable strategy to reconcile activity and selectivity, providing a design paradigm for selective biomass oxidation.