Differentiated Oxygen Evolution Behavior in MOF-Derived Oxide Nanomaterials Induced by Phase Transition.

Oxygen evolution reaction (OER) on the anode has become one of the most widely studied electrochemical processes, which poses an important role in several energy generation technologies. In this work, we have designed and synthesized a series of metal-organic framework (MOF)-derived oxides pyrolyzed at different temperatures for efficient water oxidation in alkaline solutions. First, the barrel-shaped BMM-10 microcrystals can be conveniently synthesized under solvothermal conditions, and the hollow morphology of BMM-10-Fe with low crystallinity can be obtained through the fierce hydrolysis of Fe(III) ions. After being oxidized in air, there are only two typical phases of oxides including BMM-10-Fe-L and BMM-10-Fe-H. During electrolysis, BMM-10-Fe-L turns out to be immediately degraded into active Ni/FeOOH nanosheets with improved OER performance, while there is almost no structural and morphological change in BMM-10-Fe-H due to the structural rigidity and robust stability. Furthermore, the optimal BMM-10-Fe-H exhibits a promising electrocatalytic OER performance with a low Tafel slope of 137.4 mV dec-1, a small overpotential of 260 mV at 10 mA cm-2, and a high current retention of 93.8% after the stability test. The present work would motivate the scientific community to construct various MOF-derived nanomaterials for efficient energy storage and conversion applications.