Surface amorphization advances activity and stability for acidic oxygen evolution†

The oxygen evolution reaction (OER) in acidic environments is crucial for various energy storage/conversion technologies. Enhancing acidic OER efficiency through precise optimization of the electronic structure at active metal sites remains a significant challenge. Due to structural flexibility and accessible active sites, amorphization offers a knob to enhance the activity of Ru-based catalysts. Here, we developed a RuO₂/IrO₂ composite catalyst characterized by a crystalline core and an amorphous surface structure. Density functional theory results indicate that surface amorphization can effectively lower the reaction energy barrier and accelerate electron transfer than its fully crystalline counterpart. Operando differential electrochemical mass spectrometry proved that surface amorphization inhibits the leaching of lattice oxygen. As a result, the RuO₂/IrO₂ composite demonstrates superior OER performance, achieving a low overpotential of 174 mV at 10 mA cm⁻² and remarkable stability for 95 hours in a 0.5 M H₂SO₄ electrolyte. This work inspires new design ideas for high-performance acid electrocatalysts, providing insights for developing robust, efficient materials for sustainable energy applications.