Enhanced Water Splitting Electrocatalysis over MnCo2O4 via Introduction of Suitable Ce Content

The research and development of transition metal oxides based electrocatalysts with high activity and stability for both oxygen evolution reaction and hydrogen evolution reaction via a facile design strategy is of critical importance. Herein, we fulfill both significant oxygen evolution reaction and hydrogen evolution reaction improvement in activity by hierarchically nanostructured Ce-MnCo2O4 prepared by an oxalate coprecipitation method and a followed calcination process. X-ray photoelectron spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy mappings analysis show that the hierarchically nanostructured Ce-MnCo2O4-3% sample is homogeneously modified by 1.49 wt % Ce with increased Co3+ species. We suspect that the introduction of suitable Ce content into MnCo2O4 facilitates the oxygen transfer and the formation of Co3+ species, and modifies the local chemical binding, resulting in active performance for oxygen evolution reaction (390 mV at 10 mA.cm(2) and a Tafel slope of 125 mV.dec(1)) in 1.0 M KOH solution. In addition, the Ce-MnCo2O4-3% sample also exhibits hydrogen evolution activity with overpotential of 389 mV at 10 mA.cm(2) and a Tafel slope of 96 mV.dec(1), and relatively good long-time stability for 12 h.