Molybdenum disulfide on reduced graphene oxide hybrids were developed via one pot hydrothermal route as a catalyst for hydrogen evolution reaction

Abstract

Green hydrogen production from the cathodic reaction of water splitting (hydrogen evolution reaction) is one of the most significant discoveries in recent years. In this regard, molybdenum disulfide (MoS₂) is used as an alternative catalyst for platinum due to its high availability and lower binding energy, which is close to zero. 1-T MoS₂, 3-R MoS₂, and 2-H MoS₂ are the major phases of MoS₂, and 2-H MoS₂ is the most stable form, but only the edge sites are activated, and the whole basel plane is almost inactive. Therefore, the activity of 2-H MoS₂ is based on the nature of the edges-sites. In this study, MoS₂–graphene oxide (MoS₂–GO) composites were prepared via a one-step hydrothermal method on the three distinct GO materials, which were prepared under different oxidation durations (24, 48, and 72 h) in the modified hummer’s method. The MoS₂ with differently oxidized GO was characterized by SEM, PXRD, and FTIR to disclose the characteristics of the materials. In addition, the electrochemical performance of MoS₂-GO was investigated by using linear sweep voltammetry (LSV). The results showed that MoS₂ layers were successfully grown on the surface of GO, which is prepared at the highest oxidation duration (72 h). It has a higher number of shaped edges with uniform growth. According to the FTIR results of GO and GO- MoS₂, 72 h oxidized GO has more (COOH) carboxylic groups, and the growth of MoS₂ has been initiated through COOH groups. The XRD spectrum of the MoS₂/RGO revealed that the MoS₂ prepared on 72 h oxidized GO nanosheets (MoS₂/RGO-72) had the highest d spacing value due to the inserted GO into the MoS₂ layers. Moreover, MoS₂/RGO-72 was the best catalyst for the hydrogen evolution reaction (HER) because MoS₂/RGO-72 needs the lowest potential value to initiate the HER reaction (overpotential). Finally, the growth of MoS₂ on GO is possible to change by varying the oxidation duration of GO to have MoS₂/RGO material with a greater number of activated sharp edges.