WS₂/graphene Composite With High Efficiency Hydrogen Evolution Reaction Performance

The electrocatalytic hydrogen evolution reaction（HER）has attracted wide attention because of it consumes continuons supplies electric energy and generate hydrogen.The key issue of electrocatalytic hydrogen evolution reaction（HER）is to explore efficient catalysts with low cost.For now,the widely application of Pt catalysts with brilliant catalytic performance is limited by its high cost and rare reserve.Recently,many studies showed nanostructured transition metal sulfides have excellent catalytic performance as well,and they are cheaper and abundant on the earth,which make nanostructured transition metal sulfides become alternative choices of the noble metals in hydrogen evolution reaction.In this paper,transition metal WS₂ was chosen to investigate the effect of catalytic performance in hydrogen evolution reaction.The main results in this paper are as follows:（1）In the present paper,low-boiling-point solvents（IPA:water=1:1）are adopted for the controllable preparation of ultra-thin WS₂ nanosheets by an improved liquid phase exfoliation process directly from the raw WS₂ powder.WS₂ powder by pretreatment,ultrasonication,centrifugation and other processes exfoliated WS₂ nanosheets.The thickness of obtained WS₂ nanosheets is about¹.5 nm with lateral size of¹.2μm.It is worth noting that the mesoporous structure of the as-obtained nanosheets increases the number of active edges.（2）The results of polarization curve and Tafel curves indicate that the as-obtained WS₂ nanosheets are an effective electrocatalysts towards HER with a low onset potential of 65 mV,a Tafel slope of 55 mV dec^-1.With the increase of the size of exfoliated WS₂ nanosheets,its catalytic performance increase.（3）Preparation of nanostructured graphene by an improved liquid phase exfoliation process directly from the graphite,and then preparing WS₂/GQD compounds by physical method.The catalytic performance of WS₂ nanosheets was improved with the introduction of graphene due to the increase of relative specific surface area and the velocity of charge transfer,which makes its catalytic performance improve further,with the overpotential was 42 mV.