Strengthened Ru–O Bonds for Robust Oxygen Evolution in Acid Media
Danning Li, Wenrui Ma, Mathan K. Eswaran, Chunfeng Li, Jiayi Chen, Guangxin Sun, Shibo Xi, Sergey M. Kozlov, Chunnian He, Lei Wang
Abstract
The development of cost-effective and acid-stable oxygen evolution reaction (OER) electrocatalysts is essential for the implementation of a proton exchange membrane-based water electrolyzer. Herein, we develop a catalyst composite featuring RuO 2 nanoplates on a manganese–cobalt-spinel oxide (MnCo 2 O 4.5 ) substrate for an acidic OER. The optimized RuO 2 /MnCo 2 O 4.5 catalyst composite exhibits a low overpotential of 210 mV at 10 mA cm –2 and remarkable stability with a degradation rate as low as 30 μV h –1 . Density functional calculations reveal that Co/Mn doping in the RuO 2 nanoplates significantly enhances their OER activity and stability against Ru dissolution. Additionally, the pH-dependent and kinetic isotope experiments underscore that RuO 2 /MnCoO 4.5 exhibits enhanced OER activity in an acidic electrolyte compared to that in an alkaline electrolyte, highlighting its potential for use in PEM electrolyzers. When integrated into a PEM electrolyzer, RuO 2 /MnCo 2 O 4.5 achieves an encouragingly low cell voltage of 1.83 V at 1 A cm –2 and operates stably for over 130 h with negligible degradation. Overall, this study provides in-depth insights into OER mechanisms, particularly in mitigating Ru dissolution under acidic conditions, a critical factor for the development of robust and cost-effective OER catalysts.