Binary ruthenium dioxide and nickel oxide ultrafine particles loaded on carbon nanotubes for high-stability oxygen...

RuO₂ is an efficient electrocatalyst for the oxygen evolution reaction (OER). However, during the OER process, RuO₂ is prone to oxidation into Ru^x+ (x > 4), leading to its dissolution in the electrolyte and resulting in poor stability of RuO₂. Here, we report a bicomponent electrocatalyst, NiO and RuO₂ co-loaded on carbon nanotubes (RuO₂/NiO/CNT). The results demonstrate that the introduction of NiO suppresses the over-oxidation of RuO₂ during the OER process, not only inheriting the excellent catalytic performance of RuO₂, but also significantly enhancing the stability of the catalyst for OER at high current densities. In contrast to RuO₂/CNT, RuO₂/NiO/CNT shows no significant change in activity after 150 h of OER at a current density of 100 mA cm^-2. Density functional theory (DFT) calculations indicate that NiO transfers a large number of electrons to RuO₂, thereby reducing the oxidation state of Ru. In conclusion, this study provides a detailed analysis of the phenomenon where low-valent metal oxides have the ability to enhance the stability of RuO₂ catalysts.