Preparation And Electrocatalytic Hydrogen Precipitation Performance Of Doped Molybdenum Disulfide-Based Catalyst Materials

The current global energy crisis and the environmental pollution caused by the use of fossil fuels have prompted us to think about new ways of generating energy.Hydrogen energy has the advantages of high energy efficiency,zero pollution and continuous regeneration.However,the large-scale production of hydrogen energy,as a promising new energy source for applications,is a challenge for industry,and the search for efficient,environmentally friendly and low-cost catalysts for hydrogen precipitation reactions is particularly critical.In this paper,a series of high-performance electrocatalysts with different doping amounts were synthesized through the structural design of carrier doped materials,and non-precious metal doped molybdenum disulfide-based catalysts with high hydrogen precipitation performance and relatively low cost were developed,and the related mechanisms such as electrochemical hydrogen precipitation reaction performance and catalytic active sites were analyzed and discussed.（1）Graphene preparation was carried out based on a modified Hummers method,and MoS₂/RGO composites were synthesized hydrothermally using sodium molybdate and L-cysteine as Mo and S sources,respectively,at a MoS₂:RGO mass ratio of 1.5:1.The analysis of the physical phase structure and microscopic morphology revealed that the surface was composed of closely arranged MoS₂ nanosheets,and the MoS₂ particles in the material were uniformly dispersed,and it was easier to form a structure with fewer lamellae between MoS₂ and RGO with the same particle size,which was beneficial to improve the electrochemical performance.The electrocatalytic hydrogen precipitation performance test results showed that the overpotential,Tafel slope,bilayer capacitance and impedance values of the MoS₂/RGO catalyst were 163 m V,58 m V dec^-1,18.9 m F cm^-2 and 12.0Ω,respectively.The three-dimensional RGO skeleton provided a platform with larger specific surface area for the loading of MoS₂,supported and stabilized the MoS₂ structure and accelerated the HER electron transfer.（2）Based on the optimal MoS₂ mass ratio,single-element Fe-MoS₂/RGO and nitrogen-doped MoS₂/NRGO composites were synthesized,and the effects of different elemental doping amounts on the catalytic performance of HER were explored.The results show that Fe_3%-MoS₂/RGO material with the optimal m_Fe:m_Mo 33%,good electrocatalytic performance was achieved:the overpotential is 177 m V,the Tafel slope is 50.9 m V dec^-1,and the impedance is 9.5Ω.For the optimal nitrogen-doped MoS₂/NRGO-30 electrode material,the overpotential was only 139 m V,the Tafel slope was 54 m V dec^-1,and the impedance was 11.2Ω,which has good HER catalytic performance.Single-element doping can change the electronic structure and generate more defects to form catalytically active sites,thus lowering the energy barrier.（3）Finally,the two-element doped Fe-MoS₂/NRGO composites were successfully synthesized under the conditions of obtaining the optimal doping ratios of Fe and N elements.The physical structure,microscopic morphology,hydrogen precipitation reaction activity and catalytic mechanism of the catalysts were analyzed in depth:Fe-MoS₂ bonded with NRGO sheets formed a continuous framework,which promoted the rapid electron transfer;Fe-MoS₂/NRGO possessed the largest specific surface area of103.6 m²g^-1;the overpotential was 77.8 m V,the Tafel slope was only 41 m V dec^-1,the bilayer capacitance is 74.9 m F cm^-2,and the interfacial impedance is 8.7Ω;density functional theory suggests that the energy gap is reduced to 0.1541 e V by doping the diatom.The adsorption of N atoms reduces the energy barrier required to drive the HER process,effectively promoting its conductivity.The results confirmed that the morphology and structure of porous Fe-MoS₂/NRGO nanosheets were optimally tuned after Fe and N co-doping,and the 3D nanostructures also exposed more active sites and provided a fast charge transfer pathway for electrolytic water,and the intrinsic activity of MoS₂ was sufficiently improved.