Formation and Stabilization of NiOOH by Introducing α‐FeOOH in LDH: Composite Electrocatalyst for Oxygen Evolution and Urea Oxidation Reactions

• Published in: Advanced materials (Weinheim) 2023-02, Vol.35 (7), p.e2209338-n/a
• Main Authors: Cai, Minmin, Zhu, Qian, Wang, Xiyang, Shao, Zhiyu, Yao, Lu, Zeng, Hui, Wu, Xiaofeng, Chen, Jun, Huang, Keke, Feng, Shouhua
• Format: Article
• Language: English
• Subjects: Absorption spectra; composite; Electrocatalysts; Electrochemical oxidation; Ferric hydroxide; Gibbs free energy; Heat of formation; Hydrothermal treatment; Hydroxides; Iron compounds; Materials science; Microbalances; Nickel compounds; NiOOH; Oxidation; oxygen evolution reaction; Oxygen evolution reactions; Photoelectrons; Stabilization; structure reconstruction; urea oxidation reaction; Ureas; α‐FeOOH
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202209338

NiOOH is considered as the most active intermediate during electrochemical oxidation reaction, however, it is hard to directly synthesize due to high oxidation energy. Herein, theoretical calculations predict that α‐FeOOH enables a decline in formation energy and an improvement in stabilization of NiOOH in NiFe‐based layered double hydroxide (LDH). Inspiringly, a composite composed of α‐FeOOH and LDH is well‐designed and successfully fabricated in hydrothermal treatment by adding extra Fe3+ resource, and stable NiOOH is obtained by the following electro‐oxidation method. Benefiting from strong electron‐capturing capability of α‐FeOOH, it efficiently promotes charge redistribution around the Ni/Fe sites and activates Ni atoms of LDH, verified by X‐ray photoelectron spectra (XPS) and X‐ray absorption spectra (XAS). The d‐band center is optimized that balances the absorption and desorption energy, and thus Gibbs free energy barrier is lowered dramatically toward oxygen evolution reaction (OER) and urea oxidation reaction (UOR), and finally showing an outstanding overpotential of 195 mV and a potential of 1.35 V at 10 mA cm−2, respectively. This study provides a novel strategy to construct highly efficient catalysts via the introduction of a new phase for complex multiple‐electron reactions. Owning to the strong electron‐capturing and hydrogen‐absorption capability of α‐FeOOH, NiOOH can be easily formedand stabilized in LDH, which exhibits highly efficient OER and UOR performance.