Bridged Mn―O―Ru Motifs in RuO2 Catalyst Promoting Hydrogen Production at Ampere-Level Current Density

Abstract

Accurately regulating the reactive sites of catalysts is vital for highly efficient catalytic processes but still faces considerable challenges. In view of this, a local oxidation-state asymmetric Mn-O-Ru bridged moiety is developed by introducing Mn atoms into the RuO2 host. The synergistic effect of the respective active sites on the Mn-O-Ru microstructure ensures its excellent alkaline HER performance. Theoretical calculations profiled that induced by the Mn-O-Ru bridged moiety, the water dissociation ability of Ru sites is significantly boosted, while the bridging oxygen exhibits the optimal hydrogen adsorption free energy. As predicted, the Mn-RuO2 catalyst achieved the overpotentials as low as 118 and 160 mV at the industrial level current densities of 1 and 2 A cm-2 in 1 m KOH, respectively, superior to the RuO2 and commercial Pt/C catalyst. Such a Mn-RuO2 electrocatalyst can operate stably with a long lifetime of 300 h at 10 mA cm-2 under alkaline conditions. Furthermore, it only requires 1.87 V to reach the current density of 1.0 A cm-2 when serving as the cathode in an assembled flow cell. This work provides new insight into catalytic local environment design for obtaining ideal efficient HER electrocatalysts.