Effects of 60Co γ-ray irradiation of thin-layer molybdenum disulfide for the hydrogen evolution reaction

Abstract

Molybdenum disulfide (MoS₂) with its low cost, excellent electrochemical stability and large specific surface area is expected to replace noble metals such as platinum as a new type of high-efficiency electrocatalyst. Since it is very difficult to effectively improve the catalytic performance only from intrinsic materials, we used the ⁶⁰Co γ-ray as the irradiation source to modify thin layer MoS₂ nanosheets (MoS₂ NSs), and explore the irradiation effect and the mechanism of catalytic performance improvement. The structure–activity relationship was investigated in depth by characterizing the morphology and structure of MoS₂ NSs before and after γ-ray irradiation, combined with the changes in HER performance. The results show that the irradiation-induced defects are dominated by sulfur (S) vacancies, which can efficiently regulate the intrinsic electronic structure of MoS₂ NSs. The introduction of defects increases the number of active sites on the surface of nanosheets and improves the reaction kinetics, optimizing the hydrogen evolution reaction (HER) performance. When the irradiation dose is too large, we reveal that the oxygen atoms passivate the S vacancies in the MoS₂ NSs and cause the concentration of S vacancies to decrease, resulting in the reduction of electrocatalytic performance. It is concluded that the appropriate irradiation dose is the key factor to improve the HER performance of MoS₂ NSs.