Copper-doped ruthenium oxide as highly efficient electrocatalysts for the evolution of oxygen in acidic media

The development of highly active and acid-stable catalysts for oxygen evolution reaction (OER) is necessary and challenging. In this work, we report a highly efficient Cu-doped RuO2 OER electrocatalyst (Cu-RuO2) synthesized via one-step calcination of amorphous RuCu sample in air atmosphere. Results show that the catalytic performances of Cu-RuO2 catalysts toward OER are strongly dependent on the calcination temperature. Among the series of Cu-RuO2 catalysts, Cu-RuO2 prepared at the calcination temperature of 300 °C (Cu-RuO2-300) exhibits the highest activity for OER. At the current density of 10 mA cm−2, Cu-RuO2-300 shows an extremely low OER overpotential of 201 mV, which is much lower than the benchmark commercial RuO2 (233 mV) and most noble metal/non-noble metal catalysts reported in literature. The Tafel slope is as low as 55 mV dec−1, which is also lower than that on RuO2 catalyst (76 mV dec−1), suggesting a faster OER kinetics. In addition, Cu-RuO2-300 can maintain excellent durability in H2SO4 electrolyte. During the chronopotentiometric (CP) test, the potential of Cu-RuO2-300 catalyst shows very small attenuation (65 mV) at the time of 24 h whereas that of the reference RuO2 catalyst exhibits a 127 mV of change only within 4 h of test. Large electrochemical surface area and abundant exposed high-index facets are responsible for the high catalytic performances of the Cu-RuO2-300 catalyst. This work is instructive for the design and preparation of highly efficient and stable noble metal-based OER catalysts in acidic media.