Deciphering the role of ultra-low-loaded rhodium in NiFe-MIL-53 for superior oxygen evolution reaction

• Published in: Journal of energy chemistry Vol. 100; pp. 77 - 86
• Main Authors: Jia, Jinzhi, Zhang, Jinhua, Guo, Kailu, Zhang, Lanyue, Du, Gening, You, Hao, Huang, Junfeng, Tu, Mudong, Li, Hua, Peng, Yong, Dou, Wei, Xu, Cailing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2025
• Subjects: Catalytic mechanism; Electrochemical reconstruction; NiFe-MIL-53; Oxygen evolution reaction; Oxygen evolution reaction; Electrochemical reconstruction; Rh; NiFe-MIL-53; Catalytic mechanism
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2024.08.022

Through theoretical calculations and in-situ spectroscopic techniques, the catalytic mechanism of Rh@NiFe-MIL-53 was elucidated. The in-situ formed Rh@NiFeOOH phase is identified as the active species. Additionally, single-atom Rh enhances the stability of catalyst and reduces the energy barrier of rate-determining steps, showing excellent OER performance. [Display omitted] Designing highly active and stable electrocatalysts of oxygen evolution reaction (OER) is one of the crucial challenges. In this study, a novel OER electrocatalyst, NiFe-MIL-53 modified with ultra-low rhodium (Rh@NiFe-MIL-53), is successfully prepared via the hydrothermal method. In-situ Raman spectroscopy and electrochemical impedance spectroscopy reveal that the doped Rh accelerates the phase transformation of NiFe-MIL-53 and the in-situ formed Rh@NiFeOOH is the actual active species. More importantly, the enhanced reversibility of electrochemical reconstruction between NiFeOOH and NiFe(OH)2 after doping Rh is beneficial for improving the electrochemical stability of the catalyst. X-ray photoelectron spectroscopy spectra show the strong electronic interaction between single-atom Rh and Ni/Fe in Rh@NiFeOOH. Furthermore, theoretical calculations confirm that the integration of single-atom Rh into the NiFeOOH successfully reduces the band gap, regulates the d-band center (εd), accelerates the charge transfer, and optimizes the adsorption behavior of oxygen-containing intermediates, thereby lowering the energy barrier of rate-determining steps. Consequently, the optimized Rh@NiFe-MIL-53 exhibits excellent OER activity (240 mV) with a small Tafel slope of 48.2 mV dec−1 and long-term durability (over 1270 h at 10 mA cm−2 and 110 h at 200 mA cm−2). This work presents a new perspective on designing highly efficient OER electrocatalysts.