Rapid Reconstruction on the Amorphous Surface for Boosting 5-Hydroxymethylfurfural-Assisted Hydrogen Production

Electrocatalytic oxidation of 5-hydroxymethylfurfural (HMFOR) is advantageous for the efficient upgrading of biomass-derived platform chemicals. Additionally, it can save energy in hydrogen (H 2 ) production by replacing the conventional oxygen evolution reaction. The surface reconstruction behavior on transition-metal-based materials is closely correlated with their HMFOR performance. Thus, one of the key challenges for designing efficient electrocatalysts lies in promoting the reconstruction and understanding the mechanism behind it. Herein, we report an amorphous CoNi sulfide with abundant sulfur vacancies that promote the surface reconstruction of active sites, thereby improving the HMFOR performance. The CoNiS-A@NF delivers efficient HMF upgrading with high conversion (98.5%), selective 2,5-furandicarboxylic acid production with a yield, and a Faradaic efficiency of 97%. The sulfur-deficient structure contributes to the interaction with OH –, which provides the driving force for surface reconstruction. Time-dependent operando Raman results verify a high rate of surface reconstruction on the CoNiS-A@NF surface, with the reconstruction rate even surpassing the consumption rate in the concentrated HMF electrolyte. When acting as a bifunctional electrode in a flow-mode electrolyzer, the CoNiS-A@NF exhibits an energy saving of 15.9% for simultaneously producing H 2 and 2,5-furandicarboxylic acid. The present work tracks the structural evolution of an amorphous surface and reveals the correlation with electrocatalytic performance, providing guidelines for designing efficient catalysts applied in sustainable energy conversions.