Study On Preparation Of Transition Metall Matrix Composites And Their Electrocatalytic Performance

One of the effective ways to solve the energy shortage and environmental pollution is to develop efficient and clean renewable energy,which has become the top priority of researchers'research and development.Hydrogen energy is a recognized clean new energy,which is often produced by electrolyzing water to produce hydrogen.Common high-efficiency catalysts are noble metal catalysts,which increases the cost of hydrogen production and is not conducive to industrial production and application.Among the HER catalysts developed in recent years,transition metal sulfides have become very promising candidates for platinum-free electrocatalysts in renewable energy applications.Due to its natural abundance,low cost and good catalytic performance,molybdenum-based,tungsten-based,and other chalcogenide materials have become representative non-precious materials for electrolysis of hydrogen production?HER?by water decomposition.This article designs and prepares ultra-thin transition metal-based catalysts on different supported substrates to expose more active sites.Synergistic interaction with supported materials with different conductivity improves catalytic activity,and also avoids the use of Nafion adhesives during testing.And conductive agents have the disadvantage of reducing the energy density of the catalyst.Therefore,three transition metal-based composite materials are constructed in this paper.The main contents are as follows:?1?In this work,a new type of vertical binary WS2/WO3 nano flower array has been synthesized by using a simple hydrothermal process using nickel foam?NF?as a carrier.The preparation method is convenient and green and pollution-free.The prepared materials have sheet-like and rod-like structures.The binary WS₂/WO₃/NF catalyst showed excellent electrocatalytic activity in hydrogen evolution reaction?HER?.In 1.0 M KOH solution,the Tafel slope was 39.76 mV/dec.The overpotential at a current density of 10 mA/cm² is only 106 mV,and the material also shows good performance in the stability test sheet.The framework of the binary WS₂/WO₃/NF can provide better dispersion,shorter electron transfer distance,and a strong combination between WS₂/WO₃ and NF,which can achieve excellent HER activity and stability.Compared with the reported WS2-based electrocatalyst,this hybrid material shows higher catalytic activity in HER.?2?Proposed the use of concentrated acid-oxidized carbon cloth?oCF?as the base material,and prepare a uniform and highly dispersed vertical MoS2 nanosheet array supported on oCF through hydrothermal synthesis.Due to the in-situ growth of vertical MoS2 nanosheets,more HER active sites can be exposed,and a faster charge transfer rate and ultra-long durability are shown during the hydrogen evolution test.The initial potential of HER is 129 mV,the overpotential to reach a current density of 10 mA/cm2 is155 mV,the Tafel slope is 118 m V/dec,and it has excellent long-term stability in alkaline media.It was confirmed that the oxygen functional groups on oCF may help vertical growth,and also help better dispersion of MoS2 nanosheets and a strong bond between MoS2 and oCF.The oxidation treatment of CF provides a simple and novel method for preparing transition metal sulfide electrocatalysts with excellent HER performance.?3?A simple one-step synthetic route was used to prepare a novel noble metal-free HER electrocatalyst.The composite material was based on fiberboard,and ultra-small molybdenum carbide?Mo2C?nanoparticles were embedded in nitrogen-rich carbon?NC?nanolayers at high temperature to form Mo2C@NC/fiberboard composite.In addition,the Mo2C@NC/fiberboard hybrid material showed higher electrocatalytic activity under alkaline conditions,and showed a smaller initial overpotential of 86 mV.The synergy between Mo2C and N dopants produces superactive non-metallic catalytic sites on the carbon nanolayer,which are more active than in Mo2C.Through the high-temperature graphitized fiber paperboard,the base material of the catalyst has a certain conductivity,thereby promoting the hydrogen evolution reaction rate and reaction effect of the catalyst,and playing a good synergistic effect.At the same time,the use of fiberboard can greatly reduce the production cost of composite materials,and it is hoped that it will be practically used in hydrogen production.