Optimizing electrochemical microenvironment of Ni sites by constructing Ni–WO2 heterostructure for promoting electrocatalytic conversion of methanol to formate via direct electrooxidation path

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. Graphical abstract