Effectiveness of strain and dopants on breaking the activity-stability trade-off of RuO2 acidic oxygen evolution electrocatalysts

Abstract

Ruthenium dioxide (RuO₂) electrocatalysts for acidic oxygen evolution reaction (OER) suffer from mediocre activity and rather instability induced by high Ru-O covalency. Here, the tensile strained Sr_0.1Ta_0.1Ru_0.8O_2-x (TS-Sr_0.1Ta_0.1Ru_0.8O_2-x) nanocatalysts were synthesized via a molten salt-assisted quenching strategy. The TS spacially elongates the Ru-O bond and reduces covalency, thereby inhibiting the lattice oxygen participation and structural decomposition. The synergistic electronic modulations among Sr-Ru-Ta groups both optimize deprotonation on oxygen sites and intermediates absorption on Ru sites, lowering the OER energy barrier. Those result in a well-balanced activity-stability profile, confirmed by comprehensive experimental and theoretical analyses. Our TS-Sr_0.1Ta_0.1Ru_0.8O_2-x electrode demonstrated an overpotential of 166 mV at 10 mA cm^-2 in 0.5 M H₂SO₄ and an order of magnitude higher S-number, indicating exceptional stability compared to bare Sr_0.1Ta_0.1Ru_0.8O_2-x. It exhibited degradation rates of 0.02 mV/h at 10 mA cm^-2 over 1000 h and 0.25 mV/h at 200 mA cm^-2 over 200 h. This study elucidates the effectiveness of tensile strain and strategic doping in enhancing the activity and stability of Ru-based catalysts for acidic OER.