A Conductive Two-dimensional Trimetallic FeCoNi-Benzenehexathiol π–d Conjugated Metal–organic Framework for Highly Efficient Oxygen Evolution Reaction

Abstract

The poor electrically conductivity of metal–organic frameworks (MOFs) is the main factor hinder their application in electrocatalysis field. In this work, we synthesize a conductive two-dimensional (2D) trimetallic π-d conjugated metal–organic framework (MOF) FeCoNi-BHT (BHT = 1,2,3,4,5,6-benzenehexathiol) through coordinating Co, Fe and Ni ions with 1,2,3,4,5,6-benzenehexathiol ligands. FeCoNi-BHT is demonstrated possessing homogeneously dispersed abundant Co-S4, Fe-S4, Ni-S4 single-atom active sites (14.26 wt% of the metal elements) and a large specific surface area (267.05 m2g−1). The room temperature conductivity of FeCoNi-BHT is measured to be 92 S m−1, indicating its metallic behavior. DFT theoretical calculation reveals that the π–d conjugation structure of FeCoNi-BHT is responsible for its metallic behavior. In addition, FeCoNi-BHT exhibits prominent oxygen evolution reaction (OER) activity (an overpotential of 266 mV vs. RHE at 10 mA cm−2 and a Tafel value of 58 mV dec-1) in alkaline media. The combined experimental and DFT studies reveal that the synergistic effect of Co, Fe, Ni sites of FeCoNi-BHT contribute to its prominent OER activity. This work paves a new avenue of developing 2D π-d conjugated MOFs with different metal centers as highly efficient eletrocatalysts.