| As the cleanest fuel,hydrogen is emerging as an ideal energy carrier and a suitable candidate of fossil fuels.So it is significant to look for an efficiency and sustainable technique to produce hydrogen.Although electrochemical water splitting offers an ideal way for hydrogen production,noble metals are requisited to decrease the energy loss.However,high cost and scarcity of these noble metal-based electrocatalysts severely limit their widespread applications in renewable energy conversion systems.Therefore,a great deal of effort has been made toward cost-effective and earthabundant catalysts as possible alternatives to precious metal materials.In this thesis we prepare MoS2 x Se2(1-x)and CoSe2/MoSe2 for water splitting.MoS2 x Se2(1-x)was obtained through a one-pot hydrothermal synthesis strategy.XRD,Raman,TEM,Element-mapping and XPS were used to record their crystallographic and micro-structures.It turned out that MoS2 x Se2(1-x)has similar flower-like morphology which is actually assembled from distorted and interconnected nanosheets.The layer distance of ternary MoS2 x Se2(1-x)is larger than binary compounds which also provide a new way to enhance electrocatalytic activity.The electrochemical measurements were all performed in 0.5 mol/L H2SO4 aqueous solution.As-prepared MoS2 x Se2(1-x),MoSe2 and MoS2 nanosheets were used to catalyze hydrogen evolution reaction(HER).The results of the tests revealed that the catalytic activity of ternary MoS2 x Se2(1-x)is better than MoSe2 and MoS2.The MoS2 x Se2(1-x)displays a geometric catalytic current density of-10 m A/cm2 at an overpotential of-188 m V vs.RHE and a Tafel slope of 43 m V/dec as cathodic catalytic.It is difficult to tune the x value simply by changing the molar ratios of S and Se in the hydrothermal synthesis of the MoS2 x Se2(1-x)materialsCoSe2/MoSe2 was also obtained through a one-pot hydrothermal synthesis strategy.XRD,Raman and TEM were used to record their crystallographic and micro-structures.It turned out that CoSe2/MoSe2 is assembled by MoSe2 nanosheets and CoSe2 nanoparticles which exposed more defects than binary compounds.In 0.5 mol/L H2SO4(or 1 mol/L KOH),the HER catalytic activity of CoSe2/MoSe2 is better than MoSe2 and CoSe2.The CoSe2/MoSe2 displays a geometric catalytic current density of-10 m A/cm2 at an overpotential of-175 m V vs.RHE(241m V)and a Tafel slope of 33 m V/dec.CoSe2/MoSe2 was also used to catalyze oxygen evolution reaction(OER),the catalytic activity of CoSe2/MoSe2 is also better than binary compounds. |
