Coupling efficient biomass upgrading with H₂ production via bifunctional Cu_xS@NiCo-LDH core–shell nanoarray electrocatalysts

To boost hydrogen production from water splitting, the electrochemical oxidation of biomass-derived molecules to produce valuable chemicals is regarded as a promising approach to replace the kinetically sluggish oxygen evolution reaction. Herein, copper sulfide nanowire@NiCo-layered double hydroxide (LDH) nanosheet core-shell nanoarrays are fabricated as efficient bifunctional electrocatalysts for 5-hydroxymethylfurfural (HMF) oxidation and water reduction to simultaneously produce value-added 2,5-furandicarboxylic acid (FDCA) and hydrogen fuel with less energy consumption. Benefiting from the fast charge transfer induced by the Cu_xS core, the Co/Ni interaction in the LDH nanosheet layer and the open nanostructure, the optimized catalysts exhibit superior electrocatalytic activity (record-high 87 mA cm^-2 @ 1.3 V vs. RHE for HMF oxidation; η = 107 mV @ 10 mA cm^-2 for HER) and durability; the faradaic efficiency towards FDCA and H₂ is close to unity. The bifunctional two-electrode electrolyzer only requires a low voltage of 1.34 V to co-generate H₂ and FDCA at 10 mA cm^-2. This work highlights the significance of tuning the redox properties of transition metals and constructing nanoarray electrocatalysts towards more efficient energy utilization. © The Royal Society of Chemistry 2020.