Tetrahydroxybenzoquinone-Based Two-Dimensional Conductive Metal–Organic Framework via π-d Conjugation Modulation for Enhanced Oxygen Evolution Reaction
Yantao Wang, Xiaowan Bai, Junfeng Huang, Wangzu Li, Jinhua Zhang, Hua Li, Yu Long, Yong Peng, Cailing Xu
Abstract
2D conductive metal–organic frameworks (2D c-MOFs) have attracted significant interest as efficient electrocatalysts for the oxygen evolution reaction (OER). However, effectively regulating their catalytic activity remains a significant challenge. Herein, density functional theory (DFT) was performed to explore the effect of π-d conjugation modulation on the electronic structure of the tetrahydroxy-1,4-benzoquinone-based 2D c-MOFs. The computational results indicate that the strong π-d conjugation caused by orbital hybridization between Co and Fe widens and enhances the hybridization between the d xz /d yz orbitals at the metal sites and the p orbitals of the ligands, thereby affecting the reconstruction of the MOFs during the OER process. Experimentally, CoFe-THQ with various atomic ratios was synthesized. The results indicated that the synthesized Co 0.6 Fe 0.4 -THQ powders only needs an overpotential of 247 mV to reach a current density of 10 mA cm –2 for the OER in alkaline medium, which is much lower than most reported transition metal-based electrocatalysts and even better than that of the benchmark RuO 2 electrocatalyst. Furthermore, in situ Raman and in situ Fourier transform infrared spectroscopy analyses revealed that Co 0.6 Fe 0.4 -THQ undergoes a different reconstruction evolution during the OER process compared to Co-THQ, with the mixed (Co, Fe) bimetallic oxides ((Co, Fe) 3 O 4 and α-(Co, Fe) 2 O 3 ) formed after reconstruction identified as the true active species. This study opens up an effective avenue for the rational design of high-activity 2D c-MOF electrocatalysts.