Superior role of MXene nanosheet as hybridization matrix over graphene in enhancing interfacial electronic coupling and functionalities of metal oxide

Abstract

A superior efficiency of MXene (Ti3C2) nanosheet as a hybridization matrix over graphene is evidenced by comparative investigation on uniformly-stacked MnO2–Ti3C2 and MnO2–reduced graphene oxide (rGO) nanohybrids. Density functional theory calculation and spectroscopic analyses demonstrate a stronger interfacial electronic coupling and greater charge transfer of polar MnO2 with hydrophilic Ti3C2 nanosheet than with hydrophobic rGO one, which maximizes the hybridization effect with the conductive nanosheet. Also, hybridization with Ti3C2 nanosheet is more effective in enhancing the ion diffusivity and porosity of MnO2 than that with strongly self-stacking rGO, which is attributable to weaker self-stacking tendency of Ti3C2. Due to these hybridization effects, the MnO2–Ti3C2 nanohybrid delivers larger specific capacitance with improved rate performance than does the MnO2–rGO nanohybrid, underscoring higher efficiency of MXene hybridization in improving electrode performance. This study clearly demonstrates that exfoliated MXene nanosheet can act as a superior hybridization matrix over rGO to explore strongly-coupled nanohybrids with improved energy-related functionality.