Controlled Chemical Functionalization toward 3D-2D Carbon Nanohorn-MoS2 Heterostructures with Enhanced Electrocatalytic Activity for Protons Reduction

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, in a stepwise approach, complementary functional groups are covalently introduced 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 as that of commercial Pt/C. Minute overpotential is registered, 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⁻¹, and 34.5 Ω, respectively. Furthermore, the stability of the 3D-2D CNH-MoS₂ heterostructure is validated after performing 10 000 ongoing electrocatalytic cycles.