Strain-Induced Electronic Structure Modulation on MnO2 Nanosheet by Ir Incorporation for Efficient Water Oxidation in Acid

Oxygen electrochemistry plays a key role in renewable energy technologies, such as fuel cells and electrolyzers, but its slow kinetics limits the performance and the commercialization of such devices. Here, a strained MnO2 nanosheet induced by Ir incorporation is developed with optimized electronic structure by a simple hydrothermal method. With the incorporation of Ir, the strain induces elongated Mn-O bond length, and thereby tuning the electronic structure to favor the oxygen evolution reaction (OER) performance. The obtained catalyst exhibits an excellent mass activity of 5681 A g(-1) at an overpotential of 300 mV in 0.5 m H2SO4, and reaches 50 and 100 mA cm(-2) at overpotentials of only 240 and 277 mV, respectively. The catalyst is also stable even at 300 mA cm(-2) in 0.5 m H2SO4. Using the nanosheet as the OER catalyst and the Pt/C as the hydrogen evolution reaction catalyst, a two-electrode electrolyzer achieves 10 mA cm(-2) with only a cell voltage of 1.453 V for overall water splitting in 0.5 m H2SO4. This strategy enables the material with high feasibility for practical applications on hydrogen production.