Controlled chemical functionalization toward 3D-2D carbon nanohorn-MoS2 heterostructures with enhanced electrocatalytic activity for protons reduction

TL;DR

This study develops a covalently functionalized 3D-2D heterostructure of carbon nanohorns and MoS2, significantly enhancing electrocatalytic hydrogen evolution with stability comparable to commercial catalysts.

Contribution

It introduces a novel covalent functionalization method to create stable CNH-MoS2 heterostructures with improved electrocatalytic performance for proton reduction.

Findings

Achieved low overpotential of 0.029 V for hydrogen evolution

Registered low Tafel slope of 71 mV/dec

Demonstrated stability after 10,000 cycles

Abstract

The realization of novel heterostructures arising from the combination of nanomaterials is an effective way to modify their physicochemical and electrocatalytic properties, giving them enhanced characteristics stemming from their individual constituents. Interfacing carbon nanohorns (CNHs) possessing high porosity, large specific surface area and good electrical conductivity, with MoS2 owning multiple electrocatalytic active sites but lacking significant conductivity, robust interactions and effective structure, can be a strategy to boost the electrocatalytic reduction of protons to molecular hydrogen. Herein, we covalently introduce, in a stepwise approach, complementary functional groups at the conical tips and sidewalls of CNHs, along with the basal plane of MoS2, en route the construction of 3D-2D CNH-MoS2 heterostructures. The increased MoS2 loading onto CNHs, improving and facilitating charge delocalization and transfer in neighboring CNHs, along with the plethora of active sites, results in excellent electrocatalytic activity for protons reduction same to that of commercial Pt/C. We have registered minute overpotential, low Tafel slope and small charge-transfer resistance for electrocatalyzing the evolution of hydrogen from the newly prepared heterostructure of 0.029 V, 71 mV/dec and 34.5 {\Omega}, respectively. Furthermore, the stability of the 3D-2D CNH-MoS2 heterostructure was validated after performing 10,000 ongoing electrocatalytic cycles.