S-Species-Stimulated Deep Reconstruction of Ultra-Homogeneous CuS Nanosheets for Efficient HMF Electrooxidation

Efficient utilization of renewable biomass resources is one of the feasible approaches to address the massive consumption of fossil fuels accompanying severe resource crises and environmental pollution. Currently, 2,5-furandicarboxylic acid derived from the oxidation of biomass-based 5-hydroxymethylfurfural (HMF) is a valuable chemical as the alternative to the fossil resource-derived terephthalic acid. However, the development of high-performance and low-cost Cu-based electrocatalysts for the efficient HMF oxidation reaction (HMFOR) remains an enormous challenge. Guided by our theoretical prediction, we proposed a coordination-pyrolysis strategy to fabricate highly dispersed copper sulfide (CuS) nanosheets supported on N-doped porous carbon precatalyst (CuS@NC). The covalent S species trigger the deep reconstruction of CuS nanosheets, and the in situ generated SO₄ ^2- not only promotes the formation of Cu^2+δ species but also facilitates the cleavage of α-C-H and -O-H bonds in HMF. The optimized CuS@NC achieved a high current density of 335 mA cm^-2 at 1.50 V vs. reversible hydrogen electrode, representing a remarkable 628% enhancement over the control catalyst. This study integrates theoretical predictions with experimental investigations to systematically elucidate how S species promote the deep reconstruction of CuS nanosheets to enhance the HMFOR performance and proposes a scalable strategy for preparing ultra-uniform transition metal sulfide precatalysts.