Ternary Phase Diagram-Facilitated Rapid Screening of Double Perovskites As Electrocatalysts for the Oxygen Evolution Reaction

The development of cost-effective, non-noble metal electrocatalysts for the oxygen evolution reaction (OER) is of paramount importance for sustainable technologies. Efficient screening strategies for electrocatalysts can greatly increase the commercialization speed of these advanced technologies. Here, ternary phase diagrams with large-scale tuning and designated-scale tuning strategies are applied for the first time to provide a new method for screening perovskite oxide-based electrocatalysts for OERs. Specifically, the family of double perovskites (Sr₂Fe_1.5-x-yCo_xNi_yMo_0.5O_6-δ, 0 ≤ x, y ≤ 1.5) was utilized to understand the role of transition metals in perovskite oxides. Ternary phase diagrams can facilitate a rapid screening process, provide a straightforward relationship between phase structures and catalytic activities, and help to confirm the effects of various combinations of transition metals on the OER activity. The Fe-Co system (Sr₂Fe_1.5-xCo_xMo_0.5O_6-δ) improves the catalytic activities, as demonstrated by the reduced Tafel slope and enhanced stability, while the Fe-Ni system (Sr₂Fe_1.5-yNi_yMo_0.5O_6-δ) improves the surface kinetic properties of the OER, as demonstrated by its reduced overpotential. Significantly, the Co, Ni, and Fe ternary phase systems can serve as the synergistic coactive sites (Sr₂Fe_1.5-x-yCo_xNi_yMo_0.5O_6-δ) to catalyze the OER, resulting in an improved overall OER performance. This systematic study not only demonstrates a new strategy to allow the rapid screening of double perovskite OER catalysts based on large-scale tuning and designated-scale tuning strategies but, more importantly, also provides an insightful understanding of the use of multitransition metal-based double perovskites for catalysis of the OER.