Surface functionalization of carbon cloth with conductive Ni/Fe-MOFs for highly efficient oxygen evolution

Abstract

Oxygen evolution reaction (OER) plays an important role in electrochemical energy conversion and storage. However, the slow charge transport and high free energy of intermediates conversion greatly restrain the kinetics of OER. Herein, we strategically adopt the hexahydroxytriphenylene (HHTP) ligand to prepare an impressive Ni-Fe bimetallic conductive Metal-organic framework (MOF) in-situ grown on carbon cloth ([Ni2.87Fe0.13(HHTP)2]n/CC) via the conventional one-step hydrothermal method. The obtained [Ni2.87Fe0.13(HHTP)2]n/CC was characterized by high electrical conductivity, large specific surface area and affluent nanopores, which enables the [Ni2.87Fe0.13(HHTP)2]n/CC to improve the electron conductivity and deliver more catalytic active sites. Benefitting from the synergistic interaction of bimetallic Ni-Fe site and nanostructure advantages, [Ni2.87Fe0.13(HHTP)2]n/CC shows the greatly enhanced catalytic activity of a low overpotential of 310 mV at 20 mA cm−2 towards OER. The density functional theory (DFT) calculations well corroborate that the activity improvement is mainly attributed to NiO4-FeO4 (Fe site), instead of the NiO4-NiO4 and NiO4-FeO4 (Ni site), indicating that the Fe doping increases the activity of Ni site. This work systematically examines the potential of [Ni2.87Fe0.13(HHTP)2]n/CC in the OER and provides new avenue for designing the next-generation conductive MOFs catalysts.