Optimizing Acidic Oxygen Evolution with Manganese-Doped Ruthenium Dioxide Assembly.

Abstract

Ruthenium dioxide (RuO₂) is one of the promising catalysts for the acidic oxygen evolution reaction (OER). However, designing RuO₂ catalysts with good activity and stability remains a significant challenge. In this work, we propose the manganese (Mn)-doped RuO₂ assembly as a catalyst for the OER with improved activity and stability. Consequently, the optimized 7% Mn-RuO₂ exhibits exceptional OER activity in 0.5 M H₂SO₄, delivering a low overpotential of 195 mV to achieve a current density of 10 mA cm^-2. Furthermore, it displays the highest mass activity among all the tested catalysts, reaching 587.9 A g_Ru^-1 at 1.5 V versus the reversible hydrogen electrode (vs RHE), which is 7.8 and 139.8 times higher than those of undoped RuO₂ and commercial RuO₂, respectively. Moreover, 7% Mn-RuO₂ demonstrates remarkable stability over a continuous operation to 100 h (at 10 mA cm^-2) without significant performance attenuation. Additionally, theoretical calculations indicate that Mn doping weakens the adsorption of the OER intermediates and modifies the potential-determining step (PDS) of the OER, thereby reducing the OER overpotential. Consequently, strategies involving Mn doping can effectively enhance the overall kinetics of the OER. This work offers a promising approach for the design of efficient water electrolysis catalysts.