Holey carbon-nanotube-wrapped MXene for hydrogen evolution reactions and supercapacitor applications

In recent years, interest in noble metal-free catalysts for the hydrogen evolution reaction (HERs) and supercapacitor (SCs) applications has emerging for altering the high-price of the catalyst and prohibiting the dissolution/phase change of the catalysts in long term performances. In this study, we present a novel noble metal-free electrocatalyst composed of holey carbon nanotubes (h-CNTs) and MXene nanocomposites for electrocatalytic HERs and SCs. By wrapping h-CNTs into the surface of the MXene sheet, we address the limitations of pure MXenes and achieve superior electrochemical performance. Specifically, MXenes containing 20 wt% h-CNTs exhibit a low overpotential of 192 mV versus RHE and a small Tafel slope of 48.95 mV dec ⠃1 at 10 mA cm ⠃2 in 0.5 M H2SO4 with excellent cyclic stability. The presence of C=O functional groups and the existence of a holey in CNT probably enhanced the electrocatalytic activity. The excellent wrapping of h-CNTs on MXene efficiently exhibited the HER performances because of their individual effect and the arising of synergy, where the excellent interaction attained between the immobilized atom in the h-CNT and MXene. For SCs, MXenes containing 15 wt% h-CNTs display the highest specific capacitance of 404 F g ⠃1 at 4 A/g with excellent cyclic stability, maintaining 80% capacity after 4000 cycles at 10 A/g at ambient temperature in 2 M KOH. Furthermore, the MXene@h-CNT nanocomposite was subjected to density functional theory (DFT) calculation. Our findings demonstrate that the newly developed nanocomposite offers a promising route to boost HER and SCs performance for a wide range of technological (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, a novel noble metal-free electrocatalyst composed of holey carbon nanotubes (h-CNTs) and MXene nanocomposites was developed for electrocatalytic hydrogen evolution reaction (HER) and supercapacitor (SC) applications. The electrocatalyst exhibited superior electrochemical performance, with low overpotential and small Tafel slope for HER, as well as high specific capacitance and excellent cyclic stability for SC. The presence of functional groups and the excellent wrapping of h-CNTs on MXene contributed to the enhanced electrocatalytic activity.