Interface-coupling of CoFe-LDH on MXene as high-performance oxygen evolution catalyst

Abstract

Oxygen evolution reaction (OER) is the bottleneck reaction of the overall water splitting process despite the intensive research in the past decades. Efficient yet stable low-cost OER catalysts have been widely explored but further improvement is still highly demanded. Herein, a type of hybrid OER catalyst was prepared by the growth of CoFe-LDH (layered double hydroxide) on the surface of Ti3C2 MXene nanosheets, which exhibits superior OER performance than the state-of-the-art RuO2. The enhancement of the OER performance could be attributed to the combination of oxygen-breaking ability of CoFe-LDH and metallic conductivity of Ti3C2 MXene substrate. Meanwhile, the direct growth of CoFe-LDH on the hydroxyl-rich surface of MXene effectively prevents itself from aggregation, exposing more CoFe-LDH edge active sites. What's more important is that the intimate interface between CoFe-LDH and Ti3C2 MXene brings in efficient charge transfer and oxygen activation, which is supported by the DFT calculation results. The direct growth of CoFe-LDH on MXene endows the insulating LDH with metallic features with the O 2p states become distributed above the Fermi level which is mediated by the possible anionic redox process. This work demonstrates the great potential of MXene-based hybrid nanostructure for energy conversion applications.