In-situ redispersion of Ni@C catalyst boosts 5-hydroxymethylfurfural electrooxidation by increasing Ni4+ sites

5-Hydroxymethylfurfural electrooxidation reaction (HMFOR) is a promising method for producing 2,5-furandicarboxylic acid (FDCA) and H2 under mild reaction conditions. However, improving catalytic activity is challenging due to the rate-determining step (RDS) associated with hydroxymethyl oxidation during HMFOR. Herein, we exploited Ni nanoparticles wrapped in carbon layers (Ni@C) as a model catalyst to systematically investigate the roles of optimized active sites formed via in-situ redispersion in enhancing the catalytic activity. The wrapped carbon layers promoted the in-situ redispersion of Ni nanoparticles into NiOOHx (x<1) with smaller dimensions, increasing the electrochemically active surface areas and facilitating the formation of Ni4+ sites. Experimental analysis coupled with density functional theory calculations demonstrated the remarkable boost in the RDS on the superior active Ni4+ sites, thereby accelerating the integrated HMFOR process. This work establishes a new avenue to construct highly active and stable catalysts for biomass electrooxidation valorization via the in-situ redispersion method.