Synergistic enhancement of nickel-cobalt nano-catalysts for 5-hydroxymethylfurfural conversion via electronic structure engineering and solar intensification

The electrooxidation of 5-hydroxymethylfurfural (HMF) into vital chemical intermediates has received widespread attention. In order to achieve efficient conversion of HMF, the main focus has been on the design and development of delicate catalysts. In addition, the introduction of an external field in the reaction process can also improve the electrocatalytic efficiency. In this paper, nickel-cobalt composite oxide catalysts with controlled metal centers (Ni/Co) were synthesized by a simple “coating-calcination” method. The rational rearrangement of d-electron by Co-doping facilitated the improvement of HMF adsorption, which was further confirmed by Density Functional Theory calculations. The catalysts synthesized at the optimal Co-doping ratio could still achieve 100 % of HMF conversion, 95.65 % of 2,5-furandicarboxylic acid yield, and 92.97 % of Faraday efficiency after 25 electrochemical cycles. Crucially, we introduced solar illumination to further enhance the performance of electrooxidation HMF. The catalyst performance was further improved via local photothermal effect and additional photocurrent. Therefore, the yield of FDCA was increased by more than 27 % under 2.0 kW m⁻² illuminations. An electrooxidation system constructed based on external field enhancement and catalyst design provides new insights into the efficient conversion of biomass.