3D ordered RuO <sub>2</sub>/WO <sub>3</sub> heterostructure inverse opal arrays for highly-active and stable acidic oxygen evolution reaction
Runlong Jia, Yan Tan, Aoshuang Li, Yijie Wang, Chuanwei Cheng
Abstract
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 RuO<sub>2</sub>/WO<sub>3</sub> inverse opals (IOs) catalyst to address the bottleneck problem of see-saw relationship between activity and stability, in which the crystalline and corrosionresistant WO<sub>3</sub> facilitates electron transport and stabilizes RuO<sub>2</sub>, whereas the lattice mismatch-induced amorphousdominated RuO<sub>2</sub> provides abundant unsaturated coordination sites to enhance the acidic oxygen evolution reaction (OER) activity. Consequently, the RuO<sub>2</sub>/WO<sub>3</sub> IOs demonstrates outstanding acidic OER performance in terms of a low overpotential of 180 mV to reach 10 mA·cm<sup>–2</sup>, and excellent stability for maintaining 100 hours continuous test. Experimental characterizations and density functional theory calculations reveal that interface coupling between WO<sub>3</sub> and RuO<sub>2</sub> 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 WO<sub>3</sub> supports in the heterostructures could inhibit the over-oxidation of Ru species, so as to enhance the activity and stability simultaneously.