Constructing high coordination number of Ir–O–Ru bonds in IrRuO_x nanomeshes for highly stable acidic oxygen evolution reaction

IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction (OER) catalysts, but breaking the trade-off between their activity and stability is an unresolved question. Meanwhile, addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis (PEM-WE). Herein, we prepared an IrRuO_x nanomeshes (IrRuO_x NMs) with high coordination number (CN) of Ir–O–Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor. X-ray absorption spectroscopy analysis revealed that the IrRuO_x NMs possess high coordination number of Ir–O–Ru bonds (CN_Ir–O–Ru = 5.6) with a distance of 3.18 Å. Moreover, the nanomesh structures of IrRuO_x NMs provided hierarchical channels to accelerate the transport of oxygen and water, thus further improving the electrochemical activity. Consequently, the IrRuO_x NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm⁻² and slightly increase by 70 mV over 650 h test. Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_x NMs is the adsorbent evolution mechanism, which is beneficial for the robust structural stability.