Enhanced Activities in Alkaline Hydrogen and Oxygen Evolution Reactions on MoS2 Electrocatalysts by In-Plane Sulfur Defects Coupled with Transition Metal Doping

2D transition metal disulfides (TMDs) are promising and cost-effective alternatives to noble-metal-based catalysts for hydrogen production. Activation of the inert basal plane of TMDs is crucial to improving the catalytic efficiency. Herein, introduction of in-plane sulfur vacancies (S-v) and 3d transition metal dopants in concert activates the basal planes of MoS2 (M-S-v-MoS2) to achieve high activities in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Acetate introducing mild wet chemical etching removes surface S atoms facilitating subsequent cation exchange between the exposed Mo atoms and targeted metal ions in solution. Density-functional theory calculation demonstrates that the exposed 3d transition metal dopants in MoS2 basal planes serve as multifunctional active centers, which not only reduce Delta G(H*) but also accelerate water oxidation. As a result, the optimal Ni-S-v-MoS2 and Co-S-v-MoS2 electrocatalysts show excellent stability and alkaline HER and OER characteristics such as low overpotentials of 101 and 190 mV at 10 mA cm(-2), respectively. The results reveal a strategy to activate the inert MoS2 basal planes by defect and doping co-engineering and the technique can be extended to other types of TMDs for high-efficiency electrocatalysis beyond water splitting.

Automated summary

Activation of the basal planes of MoS2 using sulfur vacancies and transition metal doping can achieve efficient hydrogen and oxygen evolution reactions. This approach can be extended to other TMDs for high-efficiency electrocatalysis.