Boosting the Electrochemical 5-Hydroxymethylfurfural Oxidation by Balancing the Competitive Adsorption of Organic and OH over Controllable Reconstructed Ni S /NiO

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) is a promising method for the efficient production of biomass-derived high-value-added chemicals. However, its practical application is limited by: 1) the low activity and selectivity caused by the competitive adsorption of HMF and OH and 2) the low operational stability caused by the uncontrollable reconstruction of the catalyst. To overcome these limitations, a series of Ni S /NiO -n catalysts with controllable compositions and well-defined structures are synthesized using a novel in situ controlled surface reconstruction strategy. The adsorption behavior of HMF and OH can be continuously adjusted by varying the ratio of NiO to Ni S on the catalysts surface, as indicated by in situ characterizations, contact angle analysis, and theoretical simulations. Owing to the balanced competitive adsorption of HMF and OH , the optimized Ni S /NiO -15 catalyst exhibited remarkable HMF electrocatalytic oxidation performance, with the current density reaching 366 mA cm at 1.5 V and the Faradaic efficiency of the product, 2,5-furanedicarboxylic acid, reaching 98%. Moreover, Ni S /NiO -15 exhibits excellent durability, with its activity and structure remaining stable for over 100 h of operation. This study provides a new route for the design and construction of catalysts for value-added biomass conversion and offers new insights into enhancing catalytic performance by balancing competitive adsorption.