Uncovering the role of the Cr dopant in RuO2 in highly efficient acid water oxidation†

The design of acidic oxygen evolution reaction (OER) electrocatalysts with high activity and durability is the key to achieving efficient hydrogen production. Herein, we report a Cr-doped RuO₂ (Ru_0.9Cr_0.1O₂) catalyst that exhibits good OER activity in acidic electrolytes. The doping of Cr increases the valence state of Ru, which enhances the activity of the catalyst, and a current density of 10 mA cm⁻² can be achieved at only 235 mV, which is superior to that of unmodified RuO₂ of 299 mV. The Tafel slope of the catalyst was 63.9 mV dec⁻¹, which is much better than that of unmodified RuO₂ at 91.1 mV dec⁻¹. In addition, this catalyst was able to maintain stable catalytic performance in 0.5 M H₂SO₄ for up to 30 hours. Density functional theory (DFT) calculations also showed that Cr doping optimized the adsorption of intermediates at Ru sites and significantly increased the catalytic activity of the Ru sites.