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

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 pi-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-S-4, Fe-S-4, Ni-S-4 single-atom active sites (14.26 wt% of the metal elements) and a large specific surface area (267.05 m(2)g(-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 pi-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 pi-d conjugated MOFs with different metal centers as highly efficient eletrocatalysts.