Oxygen vacancies confined in ultrathin nickel oxide nanosheets for enhanced electrocatalytic methanol oxidation

Owing to the relatively sluggish charge transport and reaction kinetics in nickel-based oxides, the electrocatalytic efficiency for methanol oxidation reaction (MOR) is still far below what is expected. Herein, ultrathin NiO nanosheets with abundant oxygen vacancies is put forward as an applicable catalytic model to get in-depth insights into the role that oxygen vacancies play in MOR process. Theoretical investigations reveal that the incorporation of oxygen vacancies can not only enhance the electrical conductivity of NiO crystals, but also reduce the adsorption energy of methanol molecules onto the active surface, both of which are more favorable for optimizing the overall electrocatalytic MOR performance. Thanks to the ultrathin two-dimensional (2D) features and remarkably modulated electronic structures, ultrathin NiO nanosheets with abundant oxygen vacancies exhibit a dramatically improved electrocatalytic activity for MOR, which is significantly higher than that of the sample with less oxygen vacancies and bulk NiO. This work opens a promising and feasible pathway for the design and synthesis of highly efficient non-noble MOR catalysts.