Hollow and porous NiCo2O4 nanospheres for enhanced methanol oxidation reaction and oxygen reduction reaction by oxygen vacancies engineering

The rational designing morphology and regulating active sites of catalyst is crucial to promoting catalytic performances. Herein, a series of controllable hollow NiCo2O4 nanoparticles with interconnected hierarchically porous structure and abundant oxygen vacancies were successfully constructed by a simple template-free solvothermal method and followed by heat treatment. The obtained hollow and porous NiCo2O4 exhibit interesting oxygen vacancies (Vo) defect-dependent activity, where the NiCo2O4-450-Vo show the outstanding performance in the methanol oxidation reaction (MOR) as well as the oxygen reduction reaction (ORR) with four electron reaction pathway in alkaline solution. This work may pave a facile pathway to design the hollow and porous NiCo2O4 nanospheres with the adjustable oxygen vacancies defect to accelerate various electrochemical reactions in fuel cells and other applications.