General anion-exchange reaction derived amorphous mixed-metal oxides hollow nanoprisms for highly efficient water oxidation electrocatalysis

High cost precious metal oxides (RuO2 and IrO2) electrocatalysts are required to overcome the sluggish kinetics of the oxygen evolution reaction (OER), which severely restricts the scalable application. Herein, we present a versatile anion-exchange based strategy to fabricate various amorphous transition metal oxide hollow nanoprisms with FeCo-MIL-88B template, which exhibit highly efficient OER catalysis in alkaline media. Impressively, a low overpotential of 294 mV at 10 mA cm−2 with an ultrasmall Tafel slope of 45.1 mV dec-1 and decent durability can be achieved. More importantly, the underlying origin is unraveled using the in-situ Raman spectroscopy measurement combined with the ex-situ X-ray photoelectron spectroscopy anlysis, where the electrochemically transformed metal hydroxide and oxyhydroxide species could be the real active species. This work provides a universal strategy to construct transition metal oxide hollow nanostructures with enhanced OER activity, which could push forward the advance of noble metal free electrocatalytic water splitting.