Metal‐Organic Framework‐Templated Hollow Co₃O₄/C with Controllable Oxygen Vacancies for Efficient Oxygen Evolution Reaction

Abstract Hydrogen production from water splitting is one of the effective methods to solve energy and environmental problems. However, the large overpotential of oxygen evolution reactions (OER) seriously impedes their development and application. Therefore, it is crucial to find a catalyst with low cost and high stability for OER. Herein, we report a simple method to fabricate a series of porous catalysts encapsulated with Co₃O₄ nanoparticles by carbonizing and then oxidizing MOF precursors, which can regulate and produce a large number of oxygen vacancies. The overpotentials of Z67‐Co₃O₄/C‐4 and Z9‐Co₃O₄/C‐4 are only 353 and 349 mV at a current density of 10 mA cm⁻² with a small Tafel slope of 60 and 67 mV dec⁻¹, respectively. These excellent properties can be attributed to the graphite carbon and unique hollow structure, as well as more water molecules adsorbed by oxygen vacancies, which effectively improve the conductivity and electron transfer and further promote OER activity. Thus, this preparation strategy can be applied to various MOF catalysts to regulate oxygen vacancies and thereby expanding their application in a wider range of fields.