Efficient NiFe-based oxygen evolution electrocatalysts and origin of their distinct activity

• Published in: Applied catalysis. B, Environmental Environmental, 2022-05, Vol.304, p.120937, Article 120937
• Main Authors: Han, Qinglin, Luo, Yuhong, Li, Jingde, Du, Xiaohang, Sun, Shujuan, Wang, Yanji, Liu, Guihua, Chen, Zhongwei
• Format: Article
• Language: English
• Subjects: Bimetallic NiFe catalyst; Catalysts; Density functional theory; Dissolution; Electrocatalysts; Electrolysis; Ferric oxide; Hydroxides; In situ Raman; Intermetallic compounds; Iron compounds; Nickel compounds; Oxygen; Oxygen evolution reaction; Oxygen evolution reactions; Phosphides; Surface transition
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2021.120937

Efficient oxygen evolution reaction (OER) electrocatalyst is essential for water electrolysis. Herein, high-performance NiFe-based layered double hydroxides (LDH), phosphide and sulfide OER pre-catalysts were fabricated and their distinct activity was unveiled. The as-prepared NixFe1−xS exhibits ultralow OER overpotential of 122 mV at 10 mA cm−2 in 1 M KOH. The alkali-electrolyzer using NixFe1−xS electrodes achieve superior performance exhibiting a voltage of 1.46 V at 10 mA cm−2. Experimental analysis reveals that, during OER, Fe dissolution into electrolyte occurs for NiFe LDH and NixFe1−xP, which were both converted into NiOOH, well explaining their similar activity. Interestingly, Fe dissolution is significantly mitigated in NixFe1−xS, forming partially oxidized Fe2O3/FeOOH species. Theoretical calculations confirmed that Fe2O3/FeOOH is responsible for the enhanced OER energetics of NixFe1−xS. These observations provide new insights on the distinct activity of NiFe-based electrocatalysts, guiding their rational design as well. [Display omitted] •Efficient NixFe1−xS, NixFe1−xP and NiFe LDH eletrocatalysts were fabricated for OER.•New insights on the distinct OER activity of these electrocatalysts was presented.•Fe dissolution occur for NiFe LDH and NixFe1−xP in-situ forming NiOOH catalytic phase.•Fe dissolution is mitigated in NixFe1−xS generating highly active Fe2O3/FeOOH species.