Investigation Of One-Dimensional Nanostructures Of Transition Metal Carbide And Phosphide For Water Splitting Performance

With the rapid growth of the global economy and the industrial development,the demand of energy in countries around the world continues to grow.Currently,fossil fuels are main source of energy worldwide.The use of fossil fuels increases the emission of carbon dioxide and harmful gas,which is facing the impact of environmental pollution and the greenhouse effect.As the flourish of new energy technologies such as wind energy,tidal energy,geothermal energy,and solar energy,their production capacities are of great time and space dependence.Discontinuity in energy supply and regional heterogeneity influenced the various new energy technologies for large scale applications in current production and life.Hydrogen has an important position in new energy technology because of the high energy density,combustion heat value,and the sustainable feature.It is also considered as the most potential energy in the 21st century.Water splitting technology come into being.And the produced hydrogen and oxygen are of high purity,which can meet the needs of industry.At the same time,the excess capacity caused by other new energy technologies can be used to electrolyze water to produce hydrogen and oxygen.Excess electrical energy is converted into hydrogen for energy storage,which can be widely used in new applications such as fuel vehicles to improve global energy efficiency.However,the high cost and energy consumption impede the worldwide applications.So,it is necessary to apply catalysts to reduce the barrier of the water splitting reaction.Furthermore,the current commercial catalysts such as Pt/C and Ir O₂ are expensive,and are only for a single response to catalytic performance,which cannot meet the needs for large-scale applications.Therefore,people have turned their attention to non-precious metal bifunctional catalysts,and made a lot of theoretical and experimental studies.The research focus of this thesis is bifunctional catalysts of transition metal carbides and phosphides.By adjusting the electronic structure and micromorphology,and optimizing the experimental conditions,one-dimensional carbon nanofibers were used as the matrix to obtain the bifunctional catalysts with excellent performance.Combined with various characterization methods,we explored the synergy between various elements in the material,and understood the reaction mechanism.The main content is as follows:1.Co/Mo₂C-NCNTs catalysts were prepared by a facile electrospinning method with the subsequent heat treatment.Owing to the synergy effects between Co and Mo₂C nanoparticles,the energy of the M-H bond was reduced,and the affinity of Co to OH^-was improved.The three-dimensional structure composed of carbon nanotubes and networked carbon nanofibers increased the specific surface area of the catalyst and exposed more active sites.Co/Mo₂C-NCNTs showed excellent OER and HER performances in 1 M KOH(OER:?₁₀=310 m V and HER:?₁₀=170 m V).Overall water splitting also shows excellent catalytic activity and stability during the reaction process.2.NP-Ni Co P-CNF catalysts were also prepared by electrospinning method with the subsequent heat treatment.Unlike traditional phosphating methods,non-toxic phytic acid is introduced as the phosphorus source.According to the characterization of analytical testing techniques such as EXAFS,the doping of N and P and the introduction of Ni and Co effectively improve the catalytic activity of the catalysts.The prepared NP-Ni Co P-CNF catalysts showed excellent performance for both OER and HER in 1 M KOH(OER:?₁₀=260 m V and HER:?₁₀=98 m V),and the cell voltage for water splitting was only 1.645 V.