Ultrathin amorphous Ru_0.91Ta_0.09O_x nanosheets for enhanced electrochemical stability in acidic oxygen evolution reaction

Efficient Ru-based catalysts are crucial for reducing reliance on costly Ir in acidic oxygen evolution reaction (OER). However, Ru-based oxides suffer from severe Ru dissolution and overoxidation under acidic conditions, limiting practical application. Here, we synthesized ultrathin amorphous Ru_0.91Ta_0.09O_x nanosheets with a thickness of 2.2 nm. The O K-edge X-ray absorption near-edge spectroscopy (XANES) spectra reveal a positive shift in the t_2g peak for A-Ru_0.91Ta_0.09O_x nanosheets (NSs), indicating reduced Ru–O bond covalency. Notably, A-Ru_0.91Ta_0.09Oₓ NSs exhibit outstanding acidic OER performance, delivering a low overpotential of 185  mV at 10 mA·cm⁻². Moreover, the chronoamperometry stability test shows A-Ru_0.91Ta_0.09Oₓ NSs maintained a much more stable current density over 105 h compared to A-RuO_x NSs and C-RuO₂. The Ru 3p X-ray photoelectron spectroscopy (XPS) spectra at different potentials reveal that Ta transfers electrons to Ru, suppressing peroxidation and reducing Ru dissolution, which accounts for the enhanced stability of A-Ru_0.91Ta_0.09O_x NSs. Furthermore, the enhanced stability of A-Ru_0.97Nb_0.03O_x NSs and A-Ru_0.82W_0.18O_x NSs further validate the general applicability of integrating corrosion-resistant metals with amorphous RuO_x nanosheets to boost acidic OER stability.