Study On The Synthesis And Properties Of Fe/Co Based Transition Metal Nanocomposites

In this paper,Fe/Co-based transition metal nanocomposites were successfully prepared by using metal organic framework?MOF?as the template,and the effects of the components and structures of materials on performance of electrochemical energy storage and conversion were investigated.Specific research contents are as follows:1.Study on the synthesis and electrocatalytic oxygen evolution performance of FeCo/C@Ni?OH?₂ based on CoFe-PBAUsing FeCo-based metal organic framework FeCo-PBA as the template,partially carbonized FeCo-PBA and Ni?OH?₂ nanosheets composites were successfully prepared by combinating calcining and hydrothermal process.Because of the synergistic effect between partially carbonized Fe Co-PBA and Ni?OH?₂ nanosheets,this material exhibited excellent electrocatalytic activity for oxydrogen evolution in alkaline electrolyte?1 M KOH?.First,FeCo-based metal organic framework FeCo-PBA was prepared by room temperature co-precipitation method.Then,calcining FeCo-PBA at high temperature in the atmosphere of argon to obtain partially carbonized FeCo-PBA nanocubes.The electrocatalytic oxygen evolution performance test showed that samples obtained by calcination for 2 hours at 380°C was the best.Through hydrothermal process,partially carbonized FeCo-PBA and Ni?OH?₂nanosheets composites were prepared.The experimental results showed that compared with the partially carbonized FeCo-PBA nanocubes,composite had higher activity of electrocatalytic oxydrogen evolution and excellent cyclic stability,which provided a feasible idea for the synthesis of high efficient and stable non-noble metal electrocatalytic catalyst for oxydrogen evolution.2.Study on the synthesis and supercapacitor performance of Fe/Co-based oxide hierarchical structure based on PBUsing Fe-based metal organic framework Prussian blue?PB?as the template,through ion exchange and calcination method,Fe/Co/Ni based oxide hierarchical structure were prepared.Owing to the synergy between transition metal oxides,Fe/Co/Ni based oxide hierarchical structure showed that compared with single transition metal oxides more excellent properties of supercapacitor.Firstly,Fe-based organic framework PB with different amount of Co/Ni-based hydroxide nanosheets on the surface was prepared by chemical precipitation method,and then Fe/Co/Ni-based oxide hierarchical structure was prepared by ion exchange with NaOH alcohol solution and calcination in air atmosphere.The experimental results showed that hierarchical structure of Fe-Co oxide had better supercapacitor performance,which is mainly due to the better synergistic effect between Fe/Co based oxides.3.Study on the synthesis and electrocatalytic properties of carbon nanotubes and MoS₂nanocomposites based on MOFNitrogen-doped carbon nanotubes embedded with different metal particles were prepared by calcining the mixture of Fe/Co-based metal organic frames and melamine,the relationship between calcining temperature and electrocatalytic performance of samples,and between the mass ratio of Fe/Co-based metal organic frames and melamine and electrocatalytic performance of samples was investigated.?1?Using Co-based metal organic framework ZIF-67 as the template,nitrogen-doped carbon nanotubes embedded in CoP nanoparticles and MoS₂ nanosheets composites were successfully prepared by combinating calcining,low-temperature solid-phase phosphating and hydrothermal process.Due to the similarity between CoP and hydrogenase,abundant active sites for hydrogen evolution at the edge of MoS₂ nanosheets,and the synergistic effect between CoP,nitrogen-doped carbon nanotubes and MoS₂ nanosheets,this material exhibited excellent electrocatalytic activity for hydrogen evolution in alkaline electrolyte?1 M KOH?.First,Co-based metal organic framework ZIF-67 was prepared by room temperature co-precipitation method.Then,ZIF-67 and melamine were mixed and ground at a certain mass ratio,and then calcined at high temperature in the atmosphere of argon to obtain nitrogen-doped carbon nanotubes embedded in metallic Co.The results showed that the mass ratio of ZIF-67 and melamine was 0.13,and the samples obtained after calcination for 2 hours at 700°C had the best performance of electrocatalytic hydrogen evolution.Through low temperature solid-phase phosphating process,CoP nanoparticle embedded in nitrogen-doped carbon nanotubes were prepared.The experimental results showed that compared with the nitrogen-doped carbon nanotubes embedded with metallic Co,composite has higher activity of electrocatalytic hydrogen evolution and excellent cyclic stability,which provided a feasible idea for the synthesis of high efficient and stable non-noble metal electrocatalytic catalyst for hydrogen evolution.?2?Using Fe-based metal organic framework NiFe-PBA as the template,nitrogen-doped carbon nanotubes embedded in NiFe alloy was successfully prepared by calcining.Because of the special electronic structure of NiFe alloy,abundant active sites for hydrogen evolution at the edge of MoS₂ nanosheets and the synergistic effect between Ni Fe alloy,nitrogen-doped carbon nanotubes and MoS₂ nanosheets,the material in alkaline electrolyte?1 M KOH?exhibited excellent electrocatalytic overall water splitting.Firstly,Fe-based metal organic framework NiFe-PBA was prepared by room temperature co-precipitation.Then,NiFe-PBA and melamine were mixed and ground at a certain mass ratio,and then calcined at high temperature in the atmosphere of argon to obtain nitrogen-doped carbon nanotubes embedded in NiFe alloy.Electrochemical tests showed that the mass ratio of NiFe-PBA and melamine was 0.02,and the electrochemical performance of samples obtained by calcination for 2 hours at 875°C was the best,which provided a feasible idea for the synthesis of high efficient and stable non-precious metal electrocatalytic overall water splitting catalysis.4.Study on the synthesis and electrocatalytic properties of carbon nanotubes based on MOFCarbon nanotubes and MoS₂ composite materials were successfully prepared by hydrothermal treatment of carbon nanotubes prepared in the previous chapter,and the changes of electrocatalytic properties of samples before and after loading of MoS₂ nanosheets and the influence of the loading of MoS₂ nanosheets on the electrocatalytic properties of the composites were investigated.?1?Nitrogen-doped carbon nanotubes embedded in CoP nanoparticles and MoS₂nanosheets nanocomposites was prepared by hydrothermal treatment using nitrogen-doped carbon nanotubes embedded in CoP nanoparticles as the substrate.The experimental results showed that the electrocatalytic hydrogen evolution activity of the composite was higher than that of nitrogen-doped carbon nanotubes embedded in CoP nanoparticles.When the mass ratio of nitrogen-doped carbon nanotubes embedded in CoP nanoparticles to sodium molybdate was2.5,the sample had the best electrochemical performance and excellent cyclic stability.The composite provided a feasible way for the synthesis of highly efficient and stable non-noble metal electrocatalytic hydrogen evolution catalyst.?2?Nitrogen-doped carbon nanotubes embedded in NiFe alloy and MoS₂ nanosheets nanocomposites was prepared by hydrothermal treatment using nitrogen-doped carbon nanotubes embedded in NiFe alloy as the substrate.The experimental results show that compared with nitrogen-doped carbon nanotubes embedded in NiFe alloy,the electrocatalytic decomposition voltage of the composite is lower.When the mass ratio of nitrogen-doped carbon nanotubes embedded in NiFe alloy and sodium molybdate was 2.5,the composite had the best electrocatalytic overall water performance and excellent cyclic stability which provided a feasible way for the synthesis of highly efficient and stable non-noble metal electrocatalytic overall water catalyst.