Preparation Of Molybdenum And Cobalt Based Chalcogenide For Electrocatalysis

Hydrogen is a kind of sustainable clean energy.It is an effective way to solve the energy crisis to transform the global energy structure with hydrogen as the main energy.Electrolysis of water hydrogen production is currently environmentally sustainable hydrogen production method,but in the process of electrolysis will appear a high hydrogen over potential,leading to serious energy consumption.Catalyst is an effective method to reduce hydrogen evolution potential.At present,most of the commercial catalysts are Pt precious metals,but they are expensive and have limited reserves.Therefore,the non-precious metals represented by Transition metal chalcogenides?TMDCs?have attracted extensive attention.Three kinds of TMDCs,MoS₂,MoSe₂ and CoSe₂,were studied in this paper.Firstly,this paper uses sulfur source CS₂ as a soft template,adds appropriate amount of silicon quantum dots?SiQDs?,and jointly regulates and synthesizes SiQDs-MoS₂ with CS₂.Through XRD,SEM,Raman,XPS and other test characterization methods,the influence of silicon quantum dots on product morphology,structure and phase state is explored.The results show that the MoS₂ with 3D mesh morphology is synthesized by the interaction of CS₂ and silicon quantum dots.The addition of silicon quantum dots makes mesoporous appearance and promotes the conversion of 2H phase MoS₂ to 1T phase,enhancing the conductivity of MoS₂.The electrocatalytic test results showed that SiQDs-MoS₂-2 prepared by adding 200?L quantum dots had the best electrocatalytic hydrogen evolution performance with the smallest overpotential,the Tafel slope as low as 60 mV decade^-1,and the charge transfer resistance was greatly reduced.Therefore,SiQDs-MoS₂ electrocatalyst with excellent electrocatalytic hydrogen evolution performance was synthesized.Secondly,this paper prepared MoSe₂ by means of mixed solvent heat,optimized the synthesis time,temperature and solvent ratio,and studied the influence of DMF on the structure,morphology and phase state of MoS₂ by means of XRD,SEM,XPS,Raman and TEM.The results show that when mixed solvent is used,flower spherical MoSe₂ is synthesized under the condition of H₂O:DMF=5:3,and MoSe₂ with enlarged layer spacing is obtained.At the same time,the phase of MoSe₂ changes from 2H phase to 1T phase due to molecular embedding.The electrocatalytic test results show that MoSe₂?5:3?prepared under the hydrothermal reaction condition of 180?,24 hours,H₂O:DMF=5:3had the highest electrocatalytic activity,lower Tafel slope and superior conductivity.MoSe₂ catalyst with excellent electrocatalytic performance was obtained by means of solvent heat of DMF.Finally,the hydrothermal method was used to prepare the ortho-phase CoSe₂.Through the optimization of process conditions,36 hours and 180?were obtained as the best reaction conditions.By means of XRD,SEM and Raman,the influence of time on the morphology and structure of CoSe₂ was mainly explored.The results showed that the normal phase CoSe₂ was prepared by water heat at 180?and 36 hours,presenting petal-like nanorods.Compared with CoSe₂ prepared at other times,it has the best electrocatalytic hydrogen evolution performance,and the Tafel slope is close to that of commercial Pt/C catalyst,which has great potential development value.