Deep eutectic solvent induced ultrathin Co4N/N-doped carbon nanosheets self-supporting electrode for boosting hydrogen evolution integrated with biomass electrooxidation

Metal nitrides are considered promising catalysts for the hydrogen evolution reaction integrated with electrooxidation reaction of biomass due to their metal-like properties. However, the synthesis of metal nitrides involves multi-step reactions and requires continuous reactions under a large amount of NH3 atmosphere. Herein, we exploit deep eutectic solvent (DES) to induce in-situ synthesize N-doped carbon (NC) composite Co4N ultrathin nanosheets self-supporting electrode on carbon cloth (Co4N/NC@CC) without additional input NH3 atmosphere. XAFS spectra showed that the strong interaction between Co4N and NC accelerated the electron transport at the interface, and the ultrathin nanostructure of Co4N/NC is beneficial to increasing the catalytic active sites, thereby effectively improving the catalytic performance of Co4N/NC@CC. During the HER process, Co4N/NC@CC only needs 62, 98, and 60 mV overpotentials to reach a current density of 10 mA/cm2 in alkaline, neutral, and acidic electrolytes. When Co4N/NC@CC is used to produce 2,5-furandicarboxylic acid (FDCA) and hydrogen fuel synchronously in alkaline electrolytes, only a low voltage of 1.38 V is required at 10 mA/cm2, and the conversion rate of 5-hydroxymethylfurfural (HMF) is close to 100 % and the selectivity of FDCA is 98.6 %.