The Construction And Electrochemical Characterization Of Three Dimensional Porous Carbon Based Materials Decorated With Transition Metals

The research about the development of non-noble metal based electrocatalysts with low price and high catalytic ability is of great significance to the commercialization of poton exchange membrane fuel cell,microbial fuel cell,and metal air battery because of the high price of commercial noble-metal based catalysts.Three-dimensional porous carbon-based materials,as one kind of non-noble metal based electrocatalysts,has gotten lots of attention from domestic and international scholars about their structural design and catalytic performance optimization.However,the majority of noble-metal free materials generally exhibit limited catalytic activity,which can't satisfy the practical needs.In this article,we center on the construction of three-dimensional porous carbon-based materials and regulate the electronic arrangement on the surface of the materials through introducing heteroatom nitrogen into carbon matrix.Meanwhile,highly efficient catalytic active sites are formed with the addition of transition metals and the electrocatalytic ability of materials can be promoted furthermore.The carbon nanotubes have been grown on the carbon skeleton by the in-situ growth of carbon nanotubes method and the growth of carbon nanotubes can greatly enhance the electrical conductivity and connectivity of materials.Finally,the effect of the addition of Ni/Co bimetal and different metals on the catalytic ability of materials has also been explored and a series of non-noble metal catalysts with high catalytic activity and stability have been obtained.The main research results of this article are as follows.1.Poly?methyl methacrylate??PMMA?nanospheres are prepared by emulsion polymerization method and treated as the template.Polydopamine layer can be formed on the surface of PMMA nanospheres due to the adsorption characteristics of polydopamine and three dimention porous carbon materials can be constructed.Hollow carbon spheres can be in-situ formed in the structure because of the decomposition of PMMA under high temperature and this kind of hollow spheres can provide abundant vacancies for the transportation of reactants during the reaction process.Moreover,Co element can be anchored on the surface of nanospheres through the chemical bond between Co and functional groups existed on the surface of polydopamine.The Co-N catalytic center can improve the electrocatalytic activity and stability of the materials furthermore.Compared with the sample without the adding of Co element,the on-set potential collected by oxygen reduction polarization curve of the sample with the adding of Co element has positively shifted by 109 mV,suggesting its excellent electrocatalytic ability.2.Vacuum-assisted impregnation method is adopted to fill the biomass sucrose into ordered PMMA template.Three-dimension Co-N-doped porous carbon materials are gotten after carbonization under high temperature.Carbon nanotubes can be grown on the porous carbon skeleton by the in-situ growth of carbon nanotubes method and the growth of carbon nanotubes can greatly enhance the electrical conductivity and connectivity of the materials.The electron transfer rate in the electrocatalytic process can be accelerated and the recombination between one-dimensional carbon materials and three-dimensional carbon can be achieved.The electrocatalytic performance of the sample with the presence of carbon nanotubes has been greatly improved.The zinc-air battery using the as-synthesized sample as the cathode catalyst has showed power density of 163 mW cm^-2 and high cycling stability.3.Nickel-metal organic framework?Ni-MOF?is synthesized through hydrothermal method.Silica template is introduced into Ni-MOF by in-situ embedding method and honeycomb-like three-dimensional porous carbon materials can be obtained.Based on the porous carbon and the growth of carbon nanotubes,Co element,as the second metal source,is added into the reaction system and Ni/Co polarization site can be formed.The formation of Ni/Co sites can enhance the electrocatalytic activity of materials furthermore.The results show that the catalyst has outstanding catalytic ability for oxygen reduction reaction,oxygen evolution reaction,and hydrogen evolution reaction.At the same time,the single chamber microbial fuel cell using the as-synthesized sample as the cathode catalyst has exhibited maximum power density of 1971.2 mW m^-2 and can work stably for over 250 h.The zinc-air battery using the as-synthesized sample as the cathode catalyst has showed high power density and cycling stability.4.2,4,6-?2-pyridyl?triazine?TPTZ?,as the organic linker,can combine with metal?M=Fe,Co,Ni,Cu?ions through coordinate bond.Silica nanospheres are adopted as the template and three-dimensional M-N doped porous carbon materials can be obtained.During this reaction,metal ion can coordinate with its neighbor nitrogen atoms existed in the molecular structure of TPTZ and the metal can be confined in this region.This kind of combination is beneficial for the dispersion of catalytic sites and can suppress the agglomeration of the metal sites.Besides,M-N catalytic active site can promote the stability and efficiency of the catalyst.The results illustrate that Fe-based catalyst prepared in the experiment has showed the highest catalytic ability for oxygen reduction reaction.By the comparison of the catalytic activities of different samples with different metal?Fe,Co,Ni,and Cu?adding,the results illustrate that Fe-based catalyst prepared in the experiment has showed the highest catalytic ability for oxygen reduction reaction.Especially,the catalytic activity of Fe-based catalyst surpasses commercial Pt-C catalyst in 0.1 M KOH solution and the results indicate that the adding of Fe is the most effective way for synthesizing catalytic materials with high catalytic performance.