Synergetic Engineering of High-Oxidation-State Cations on Phase Boundaries toward High-Efficiency Water Splitting

Graphical On the edge : High-energy interfaces with high-oxidation-state cations synergy were designed to induce lattice distortion. As-obtained Fe-o-NiAlOH presents super-hydrophilicity and excellent catalytical activity toward oxygen and hydrogen evolution reaction with 202 mV and 180 mV to drive 10 mA cm −2 , respectively. This work offers an effective well-defined electrocatalyst and shows the synergetic protocol of unstable high-oxidation-state cations and lattice defects for high-performance water decomposition catalysis. Interfacial structure engineering with multiple high-oxidation-state cations, especially those that show unstable higher-valence during catalysis towards superior electron synergy, for high-performance electrocatalysis is of great interest and full of challenges. Lattice distortion from lattice strain at phase boundaries as a result of interfacial structure engineering is also appealing. Fe oxyhydroxide containing Fe 3+ lead to unstable Fe 4+ with a short lifetime on edge/defect sites during steady-state water-oxidation catalysis. Such material was deliberately installed to achieve atom-scale combination with Ni 3+ relevant layered double hydroxide to construct high-energy interfaces for high-oxidation-state cations synergy and induce lattice distortion. The Fe-o-NiAlOH exhibited prominent property toward oxygen evolution reaction with 202 mV to drive 10 mA cm −2 . Fe-o-NiAlOH also showed hydrogen evolution reaction activity, requiring an overpotential of 180 mV for 10 mA cm −2 . Alkaline water electrolyzer with Fe-o-NiAlOH as both anodic and cathodic electrodes required only 1.64 V to reach 10 mA cm −2 . This work offers an effective well-defined electrocatalyst and shows the synergetic protocol of unstable high-oxidation-state cations and lattice defects for high-performance water decomposition catalysis.