Enhanced surface reconstruction of V-doped Ni₃N driven by strong OH adsorption to boost 5-hydroxymethylfurfural electrooxidation for energy-saving H₂ production

Coupling biomass electrooxidation with the hydrogen evolution reaction (HER) provides an alternative approach for simultaneously increasing the energy efficiency of H₂ production and producing high value-added chemicals. Here, a V-doped Ni₃N bifunctional electrocatalyst is designed and exhibits high efficiency for both the 5-hydroxymethylfurfural oxidation reaction (HMFOR) and HER. The doped V could enhance the surface reconstruction of 5%V-Ni₃N for forming active (oxy)hydroxide species to accelerate the HMFOR. Density functional theory calculations reveal that the enhancement is attributed to the modified d-band center and strong interaction with the OH adsorbate enabled by introducing V. 5%V-Ni₃N displays a high HMF conversion and FDCA yield of 100% and 98%, and the production rate reaches 403 μmol cm⁻² h⁻¹ at 1.475 V vs. the reversible hydrogen electrode. Meanwhile, 5%V-Ni₃N shows a low overpotential of 34.8 mV towards the HER at a current density of 10 mA cm⁻². With bifunctional 5%V-Ni₃N serving as the electrode, the required cell voltage to reach a current density of 200 mA cm⁻² in a continuous HMFOR-HER system is 500 mV lower than that for water splitting. These findings not only display an efficient strategy for constructing a bifunctional electrocatalyst, but also provide a design idea for exploring catalytic materials with structural transformation.