Controllable and facile preparation of Co9S8–Ni3S2 heterostructures embedded with N,S,O-tri-doped carbon for electrocatalytic oxidation of 5-hydroxymethylfurfural

Abstract

Electrochemical oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) is a highly promising strategy for producing biomass-based valuable chemicals. Exploration of robust and cost-effective electrocatalysts for HMF oxidation is of significant importance. Here, we proposed a facile and controllable strategy for the preparation of carbon-based heterostructures by direct pyrolysis of rationally designed precursor deep eutectic solvents. The as-prepared Co₉S₈–Ni₃S₂@N,S,O-tri-doped carbon (NSOC) heterostructures exhibit an excellent HMF electrooxidation performance with a conversion of nearly 100%, a Faraday efficiency of 98.6% and a selectivity of 98.8% owing to the unique hollow structure and ternary heterogeneous interface. X-ray photoelectron spectroscopy analysis and theoretical calculations confirm the electron transfer from Ni₃S₂ to NSOC and Co₉S₈ at the heterogeneous interfaces, where hole accumulation on Ni₃S₂ is beneficial for optimizing the HMF electrooxidation reaction (HMF EOR).