Oxyanion Engineering Suppressed Iron Segregation in Nickel-Iron Catalysts Toward Stable Water Oxidation.

Liao, Hanxiao; Ni, Ganghai; Tan, Pengfei; Liu, Kang; Liu, Xuanzhi; Liu, Hele; Chen, Kejun; Zheng, Xusheng et al. · Adv Mater · 2023

basic_science · Level V

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Abstract

Nickel-iron catalysts represent an appealing platform for electrocatalytic oxygen evolution reaction (OER) in alkaline media because of their high adjustability in components and activity. However, their long-term stabilities under high current density still remain unsatisfactory due to undesirable Fe segregation. Herein, a nitrate ion (NO<sub>3</sub> <sup>-</sup> ) tailored strategy is developed to mitigate Fe segregation, and thereby improve the OER stability of nickel-iron catalyst. X-ray absorption spectroscopy combined with theoretical calculations indicate that introducing Ni<sub>3</sub> (NO<sub>3</sub> )<sub>2</sub> (OH)<sub>4</sub> with stable NO<sub>3</sub> <sup>-</sup> in the lattice is conducive to constructing the stable interface of FeOOH/Ni<sub>3</sub> (NO<sub>3</sub> )<sub>2</sub> (OH)<sub>4</sub> via the strong interaction between Fe and incorporated NO<sub>3</sub> <sup>-</sup> . Time of flight secondary ion mass spectrometry and wavelet transformation analysis demonstrate that the NO<sub>3</sub> <sup>-</sup> tailored nickel-iron catalyst greatly alleviates Fe segregation, exhibiting a considerably enhanced long-term stability with a six-fold improvement over FeOOH/Ni(OH)<sub>2</sub> without NO<sub>3</sub> <sup>-</sup> modification. This work represents a momentous step toward regulating Fe segregation for stabilizing the catalytic performances of nickel-iron catalysts.