Interface-induced enhancement of paired electrolysis in 5-hydroxymethylfurfural-H2O system on symbiotic nickel/molybdenum nitride heterostructure

Pairing the hydrogen evolution reaction (HER) with the thermodynamics-friendly electrooxidation reaction (EOR) is a powerful way to maximize the energy/economic effectiveness, but still a challenge. Herein, the symbiotic Ni/MoN heterojunction arrays were constructed on foam (Ni/MoN/NF) by the nitridation-induced in situ reduction/conversion strategy. The fascinating interfacial electronic structure and surface reconstruction of Ni/MoN/NF heterojunction are responsible for the enhanced HMF-H2O paired electrolysis. Ni/MoN/NF only requires a low overpotential of 53 mV to reach the HER current density of 10 mA cm−2, as well as the good durability; and NiOOH derived on the anode are electronically activated by MoN to achieving high-efficiency conversion from HMF to FDCA (∼100 % conversion, 97.5 % yield and 97.4 % Faradaic efficiency). For the HMF-H2O paired electrolysis, the assembled Ni/MoN/NF||Ni/MoN/NF electrolyzer only requires a low potential of 1.391 V to yield the current density of 10 mA cm−2, ranking at the forefront in the reported coupling catalysts. Theoretical calculations manifest that the upshift of d-band center of the NiOOH/MoN heterojunction contributes to HMF chemisorption and activation, thereby enhancing its catalytic activity towards HMFEOR. Our study sheds light on the significance of designing the paired electrolysis with low voltage input for renewable energy applications.