Synthesis And Electrocatalytical Hydrogen Evolution Performance Of MoS_x/P-CNTs Composites

Hydrogen,as a kind of clean energy with merits of green and sustainable,has received extensive attention from all countries and is recognized as the most promising new energy source since the increasing prominence of energy and environmental issues.Electrochemical hydrogen evolution reaction?HER?is a promising approach to produce H₂ because of its advantage of high efficiency,high purity and simple operation process.However,the required catalyst should possess high activity and stability,low-costing,large-scale production,so,how to prepare the active electrode material with high performance is one of the hot topics in current research.In this paper,the MoS_x/P-CNTs composite was prepared by a facile hydrothermal process,and the influence of different factors on the properties of its HER performance was investigated.The P-CNTs was obtained by a pyrolysis process.The experiment indicated that the incorporation amount of P increased along with the pyrolysis temperature.Both high temperature process and P incorporation led to the diameter of CNTs being larger and the crystalline being deteriorated,which is beneficial to reduce the chemical inertness on the surface of CNTs and make it easy to form stable composite with other substances.The flower-like MoS_x was synthesized by hydrothermal process.The further investigation suggested that MoS_x was amorphous and contained lots of unsaturated S atom.When it was annealed at high temperature,the MoS_x material recrystallized and transferred to be hexagonal MoS₂ finally,which has a poor electrochemical performance.The MoS_x/P-CNTs composite was prepared by a facile hydrothermal process.The experiment indicated that high temperature process as well as P incorporation could reduce the chemical inertness on the surface of CNTs,which reduced its self-agglomeration characteristics in some sense,making the MoS_x and P-CNTs can form stable composite.On the other hand,the addition of P-CNTs effectively improved the conductivity of MoS_x materials,which is in favour of the improvement of electron transportation and the composite electrochemical performance during the HER process.The MoS_x@P-CNTs composite was prepared by urea-assisted synthesis via a facile hydrothermal process.The corresponding characterization analysis suggested that leaves-like MoS_x nanosheets were uniformly anchored on P-CNTs substrate to form an original leaves-branch architecture.What is more,orthogonal experimental results showed that the impact factors to overpotential of?₁₀ of MoS_x@P-CNTs composite in-order is hydrothermal temperature,hydrothermal time and the dosage of PMA and P-CNTs,P doping amount.In addition,the amount of active catalyst coated electrode also played a certain influence on the performance of HER.Electrochemical tests indicated that the MoS_x@P-CNTs composite had excellent electrochemical performance and stability,with an overpotential of 151 mV?vs.RHE?to reach a current density of 10 mA cm^-2 and a smaller Tafel slope of 49 mV dec^-1.Moreover,the overpotential of?₁₀ only has a 17 mV recession at the current density of 80 mA cm^-2 after 2000 CV cycles,which can be ascribed to the synergistic effect of MoS_x nanosheets and P-CNTs substrate.