In situ activation of Br-confined Ni-based metal-organic framework hollow prisms toward efficient electrochemical oxygen evolution

• Main Authors: Cheng, Weiren, Xi, Shibo, Wu, Zhi-Peng, Luan, Deyan, Lou, David Xiong Wen
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Chemical engineering; Energy-Storage; Electrocatalysts
• Online Access: https://hdl.handle.net/10356/154363
• Institution: Nanyang Technological University

Fundamental insights into the structural evolution of oxygen electrocatalysts under operating conditions are of substantial importance for designing efficient catalysts. Here, on the basis of operando x-ray absorption fine structure spectroscopy, we probe the in situ activation of Br-confined conductive Ni-based metal-organic framework (Br-Ni-MOF) hollow prisms toward an active oxygen electrocatalyst during the oxygen evolution reaction (OER) process. The successive structural transformations from pristine Br-Ni-MOF to a β-Ni(OH)2 analog then subsequently to a γ-NiOOH phase during OER are observed. This post-formed γ-NiOOH analog manifests high OER performance with a superior overpotential of 306 mV at 10 mA cm−2 and a high turnover frequency value of 0.051 s−1 at an overpotential of 300 mV, making Br-Ni-MOF one of the most active oxygen electrocatalysts reported. Density functional theory calculations reveal that the strong electronic coupling between Br and Ni atoms accelerates the generation of the key *O intermediate toward fast OER kinetics.