High activity and excellent durability of oxygen-vacancy-rich ruthenium manganese oxide solid-solution nanowires for the oxygen evolution reaction in acidic media

Abstract

Oxygen vacancy (OV)-rich solid-solution ruthenium manganese oxide nanowires (V-Ru_xMn_1−xO₂ NWs), synthesized by the hydrothermal reaction of metastable MnO₂ nanosheets in the presence of RuCl₃ with the use of CoCl₂ as the OV producer, are reported to be efficient and stable catalysts for acidic oxygen evolution reaction (OER). They only need an overpotential of 200 mV to drive 10 mA cm⁻² and show excellent durability for >600 h in 0.5 M H₂SO₄. Their mass activity is >35.9 times higher than that of commercial RuO₂. The strong Ru–O–Mn bond interaction achieved by the solid solution structure and the OVs are the main origins of their high activity and excellent durability for the acidic OER. The Ru–O–Ru bonds are not favorable for the high catalytic activity of the V-Ru_xMn_1−xO₂ NWs. The DFT calculations indicate that both the strong Ru–O–Mn bond interaction and the OVs can decrease the energy barrier of the OER rate-determining step and suppress Ru demetallation, improving the catalytic activity and stability of the V-Ru_xMn_1−xO₂ NWs. A water electrolyzer with the V-Ru_xMn_1−xO₂ NWs exhibits a low voltage of 1.48 V to deliver 10 mA cm⁻² and shows no obvious performance drop for >300 h at 10 mA cm⁻², respectively.