Interstitial atom-doped NiFe alloy as pre-catalysts boost direct seawater oxygen evolution

Abstract

NiFe-based materials are excellent OER electrocatalysts. However, it is difficult to stabilize anions and cations during reconstruction, which also leads to the problem of high valence metals at low levels and poor stability in direct seawater. Herein, we propose the strategy of using interstitial P atom-doped NiFe alloys (P4.8-NiFe ANs-400) as pre-catalysts to stabilize anions and cations, thereby promoting the formation of abundant high-valent metal species and excellent activity and stability in direct seawater. The reconstructed P4.8-NiFe ANs-400 catalyst generates a large amount of high-valence transition metal Ni4+, which contributed to its low overpotential (214 mV) and long-term stability (100 h) in a seawater electrolyte at 100 mA cm−2. Experiments and theoretical calculations show that the interstitially doped P atoms share the charge around the Fe and the active Ni sites, optimizing the free energy of the OER intermediate and making the chlorine evolution reaction (CER) difficult to proceed.