Interface modulation of perovskite oxides to simultaneously enhance the activity and stability toward oxygen evolution reaction

Perovskite oxides hold great promise as the oxygen evolution reactions (OER) electrocatalysts owing to the merits of high intrinsic activity, flexible structures and rich abundance. Nevertheless, perovskites suffer from low electrical conductivity and poor stability. To solve above critical issue, coating the perovskites with carbon shell is a promising strategy. However, it is challenged by the conflicting preparation conditions for perovskites (oxidizing atmosphere) and carbon (reducing/inert atmosphere), which leads to a collapse of the perovskite structure during coating carbon and thus makes the coating process very difficult or even impossible. Herein, we developed a novel approach to successfully in situ coat an ultrathin carbon shell and exsolve homogeneous alloy nanoparticles on the surface of perovskite Sr2Fe1.3Ni0.2Mo0.5O6-δ (SFNM) (as the model material) to form the core–shell structure for the first time. Such constructed SFNM with coating carbon shell exhibits a low overpotential of 0.33 V at the current density of 10 mA cm−2 and excellent stability for as long as 160 h. Benefiting from the interface modulation, the core–shell structured catalyst exhibits an extraordinary OER activity and stability, far surpassing pristine SFNM and state-of-the-art RuO2. Through a combined experimental and theoretical approach, such carbon shell is energetic favorable for facilitating the OER process through generating built-in electric field, shifting the position of d-band center toward Fermi energy and decreasing the energy barrier of active sites. Moreover, the stability is significantly improved by the robust carbon shell protecting the perovskite from alkaline corrosion. Notably, this strategy can be extended to other electrocatalysts, enabling both superior activity and stability.