Anionic Regulation and Heteroatom Doping of Ni-Based Electrocatalysts to Boost Biomass Valorization Coupled with Hydrogen Production

Electrocatalytic biomass valorization coupled with hydrogen production provides an efficient and economical way to achieve a zero-carbon economy. Ni-based electrocatalysts are promising candidates due to their intrinsic redox capabilities, but the rational design of active Ni site coordination is still a huge challenge. Herein, the combined strategies of surface reconstruction and heteroatom doping are adopted to modify Ni3S2 pre-catalysts and the obtained bimetallic catalyst exhibits superior electrocatalytic performance toward 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furanedicarboxylic acid (FDCA). Specifically, the oxysulfide-coordinated amorphous NiOOH (NiOOH-SOx) active phase is in situ constructed following the anionic regulation mechanism, which endows numerous defects and unsaturated sites for anodic HMF oxidation. Cu heteroatom doping further modulates the electronic structure of active sites with abundant Lewis acidic sites, offering advanced capability for HMF adsorption. Several operando characterization techniques (in situ Raman, infrared, and electrochemical impedance spectroscopies) are performed to disclose the reaction pathway and structure-activity-potential relationship. Theoretical results further demonstrate that Cu doping and oxyanionic regulation effectively modulate the local coordination environment of Ni sites and correspondingly tailor the intermediate adsorption behavior and then promote the reaction kinetics. Moreover, a two-electrode system is assembled to pair HMF oxidation with cathode hydrogen production, demonstrating better energy conversion efficiency. Transitional metal doping (Cu, V, Zn, and Fe) and oxyanionic regulation effectively modulate the local coordination environment of Ni sites and correspondingly tailor the HMF and OH adsorption behavior, and finally promote the reaction kinetics. Further pairing with cathode hydrogen production in a two-electrode electrolyzer demonstrates better energy conversion efficiency.image