Preparation Of Molybdenum Disulfide Composite Materials And Its Electrochemical Hydrogen Evolution Properties Of The Research

Nano-structured molybdenum disulfide（MoS₂） catalysts have been extensively developed for the hydrogen evolution reaction（HER）.A novel hydrothermal intercalation approach is employed to fabricate nanoflower-like 2H–MoS₂ with the incorporation of three polymers, polyvinylpyrrolidone（PVP）, polyvinyl alcohol（PVA）, and polyethylenimine（PEI）. The as-prepared MoS₂ specimens were characterized by techniques of scanning electron microscope（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, together with Raman and Fourier transform infrared spectroscopy（FTIR）. The HER properties of these lamellar nanoflower-like composites were evaluated using electrochemical tests of linear sweep voltammetry（LSV）, Tafel polarization, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.The existent polymer enlarges the interlayer spacing of the lamellar MoS₂, and reduces its stacked thickness. The lamellar MoS₂ samples exhibit a promoting activity in HER at low additions of these three polymers（0.04 g/g MoS₂ for PVA and PEI, and 0.08 g/g MoS₂ for PVP）. This can be attributed to the fact that the expanded interlayer of MoS₂ can offer abundant exposed active sites for HER. Conversely, high additions of the polymers exert an obvious interference in the HER activity of the lamellar MoS₂. Compared with the samples of MoS₂/PVP–0.08 and MoS₂/PEI–0.04, the MoS₂/PVA–0.04 composite exhibits excellent activity in HER, in terms of higher current density and lower onset potential.In order to further improve the electrochemical performance of molybdenum disulfide. The molybdenum disulfide（MoS₂）/nickel-phosphorus（Ni-P） composites obtained via a solvothermal synthesis process have been developed for hydrogen evolution reaction（HER） in a basic solution. Herein, the effects of addition for Ni-P powders and the phosphorus content on the structure and HER activity of the composites were evaluated. The as-prepared composites were characterized by techniques of X-ray diffraction（XRD）, scanning electron microscope（SEM）, Raman spectroscopy, X-ray photoelectron spectra（XPS）. The HER properties of these composites were evaluated using electrochemical tests of linear sweep voltammetry（LSV）, Tafel polarization, cyclicvoltammetry（CV） and electrochemical impedance spectroscopy（EIS）. The formation of MoS₂ on the surfaces of Ni-P powders enhances the crystallizations of them, and the metastable phosphides can be validated. Also, during the incorporation between MoS₂ and Ni-P powders, the 2H-MoS₂ tends to transfer to the monolayer phase of 1T-MoS₂. The coexistences of phosphides and 1T-MoS₂ are exactly benefit for the enhancement in HER.Among the composite, the MoS₂/Ni-LP-0.36, MoS₂/Ni-MP-0.36 and MoS₂/Ni-HP-0.36 composites show the excellent HER performance; among these three samples,MoS₂/Ni-MP-0.36 exhibits the remarkably electrocatalytic activity. The prominent HER behavior of the MoS₂/Ni-P composite can be due to the synergetic effects of the presence of monolayer 1T-MoS₂ on the surface, the excellent conductivity of Ni-P powder at the bottom, as well as the coexistence of phosphides.