Optimizing electrochemical microenvironment of Ni sites by constructing Ni–WO ₂ heterostructure for promoting electrocatalytic conversion of methanol to formate via direct electrooxidation path

Abstract Nickel‐based catalysts display promising potential in integrated hydrogen production through methanol electrooxidation (MOR). The unavoidable self‐oxidation from Ni(OH) 2 to NiOOH severely restricts their MOR performance. To inspire the progress of MOR before self‐oxidation of Ni species by altering reaction pathways, a heterostructured Ni–WO 2 catalyst is constructed to follow the direct electrooxidation pathway of methanol. In‐situ/ex‐situ characterization techniques combined with density functional theory calculations reveal the constructed Ni–WO 2 heterostructure alters the electronic structure of Ni site. It’s found Ni–Ni bond in Ni–WO 2 becomes longer and the electrons transfer from Ni sites to W sites. This results in upshifted d band center of Ni site and its closing to the Fermi energy level, which optimizes the CH 3 OH adsorption and the deprotonation of *CH 3 O into *CH 2 O in potential‐determining step. Moreover, the formed asymmetric adsorption sites increase the polarity of the methanol and the intermediate. As expected, CH 3 OH molecule is highly converted into HCOOH via direct electrooxidation pathway. This obtained Ni–WO 2 exhibits superior MOR activity with high peak current density of 325.26 mA cm −2 and performs long term of 90 h at 10 mA cm −2 in hydrogen production. This work provides an important guidance for designing efficient Ni‐based samples for direct electrooxidation of methanol.