3D ordered RuO₂/WO₃ heterostructure inverse opal arrays for highly-active and stable acidic oxygen evolution reaction

Development of highly active and stable acidic oxygen evolution reaction catalyst is very important for efficient water splitting while remains challenging. Herein, we report a highly ordered RuO₂/WO₃ inverse opals (IOs) catalyst to address the bottleneck problem of see-saw relationship between activity and stability, in which the crystalline and corrosion-resistant WO₃ facilitates electron transport and stabilizes RuO₂, whereas the lattice mismatch-induced amorphous-dominated RuO₂ provides abundant unsaturated coordination sites to enhance the acidic oxygen evolution reaction (OER) activity. Consequently, the RuO₂/WO₃ IOs demonstrates outstanding acidic OER performance in terms of a low overpotential of 180 mV to reach 10 mA·cm^–2, and excellent stability for maintaining 100 hours continuous test. Experimental characterizations and density functional theory calculations reveal that interface coupling between WO₃ and RuO₂ can enhance the spin polarization of electrons and increase the overlaps of the electronic projected density of states between the Ru d orbitals of active metal and the O p orbitals of oxygen intermediates, facilitating OER pathway to switch from lattice oxygen mechanism to adsorbate evolution mechanism, which significantly decreases the reaction energy barrier of OER process. Meanwhile, the rich oxygen vacancies and WO₃ supports in the heterostructures could inhibit the over-oxidation of Ru species, so as to enhance the activity and stability simultaneously.