Hetero-Atomic Pairs with a Distal Fe 3+ -Site Boost Water Oxidation.

The hetero-atomic interaction has been the subject of many investigations, due to their heterogeneity, the individual roles of the atoms are still difficult to realize. Herein, an electrocatalyst with a hetero-atomic pair confined on a tungsten phosphide (WP) substrate so that the Fe 3+ -site of the pair is distal to the surface is shown to deliver an extremely low overpotential of 192 mV at 10 mA cm -2 and one of the highest oxygen production turnover frequencies (TOF) of 2.1 s -1 at 300 mV under alkaline environment for the oxygen evolution reaction (OER). Operando characterization shows the Lewis acidic Fe 3+ site boosts a large population of Co 4+/3+ and the deprotonation of coordinated water, allowing simultaneously enhanced electron-transfer as well as the proton-transfer. A significant contribution from the WP substrate modulates the order of hydroxide transfer in the pre-equilibrium step (PES) and rate-determining-step (RDS), leading to a remarkable OER performance.