Ce-induced regulation of electron density enhanced the catalytic activity of Co-Mn oxides for water oxidation.

The incorporation of Ce into Co-Mn oxides induced the charge redistribution of Co and Mn via electronic coupling, which facilitated the Co 3+ /Co 4+ transition. Thus, the overpotential at 10 mA cm -2 was reduced significantly by 73 mV for the oxygen evolution reaction after Ce doping.