Hybrid heterojunction of molybdenum disulfide/single cobalt atoms anchored nitrogen, sulfur-doped carbon nanotube /cobalt disulfide with multiple active sites for highly efficient hydrogen evolution

Abstract

A multicomponent 3D monolithic electrode was designed that consists of Co single atoms anchored/nitrogen, sulfur co-doped carbon nanotubes (CoSAs-NS-CNTs) on carbon cloth (CC) with ultra-thin MoS2 nanosheets externally decorated and ultra-small CoS2 nanodots internally confined (MoS2/CoSAs-NS-CNTs@CoS2/CC) to form a hybrid heterojunction electrode with double interfaces as vectorial electron transport pathways for promoting electrocatalytic performance. The integration of well-distributed MoS2 nanosheets and CoS2 nanodots linked with Co single atoms anchored/N, S co-doped CNTs endows abundant multiple active sites, outstanding conductivity, and the downshifted d-band center with a thermodynamically favorable hydrogen adsorption free energy (ΔGH*) for effectively catalyzing hydrogen evolution reaction (HER). As a result, the optimal MoS2/CoSAs-NS-CNTs@CoS2/CC electrode exhibits outstanding HER performance with overpotentials of 72 and 56 mV at 10 mA cm−2 and small Tafel slopes of 59.4 and 43.2 mV dec-1 in acidic and alkaline solutions, respectively, outperforming most of the previously reported molybdenum/cobalt sulfide-based electrocatalysts. Moreover, the electrode also displays good durability and stability reflected from the small decrease on activity after 5000 CV cycles and nearly no decay in current density after electrolysis for 20 h.