Preparation Of Carbon/Metallic Compound Composites And Their Application In Electrocatalysis

With the growth of the world’s population,the demand for energy is increasing gradually,what’s more,the use of a large number of fossil energy causes environmental damage.In order to relieve the crisis of current energy and environment,new clean energies are urgently needed.Electrocatalytic reaction,due to its advantages of high efficiency,low emission,environmental protection and low price,can alleviate the current problems greatly.Noble metals,such as Pt/C,Ru O₂ and Ir O₂ are excellent catalysts for electrocatalytic reactions.However,the widespread application of these catalyst materials have made them faced with great obstacles,because their high prices,poor stability and other problems made them difficult to be widely applied.Therefore,based on the high conductivity and excellent chemical stability of the carbon materials.The combination of transition metal compounds and carbon materials made them appropriate as electrocatalysts for bifunctional catalytic reactions.In this work,different transition metal compounds are combined with carbon matrix.Therefore,their electrochemical properties are studied and the main research contents and conclusions are as follows:1.The catalyst materials were synthesized by one-step hydrothermal method using carbon nanotubes with the excellent conductivity as conductive matrix.With the cobalt nitrate as cobalt source and the trithiocyanuric acid trisodillm salt as sulfur source to form the Co₉S₈nanoparticles.Then,these Co₉S₈ nanoparticles of with uniform size were embedded on the surface of carbon tubes.Through discussing the synergistic effect of sulfur bond between cobalt sulfide nanoparticles and carbon nanotubes,the acceleration of sulfur bond on the bifunctional catalytic reaction of electrocatalytic oxygen evolution（OER）and electrocatalytic oxygen reduction（ORR）was clearly analyzed.After analyzing the catalytic performance,it can be concluded that this catalyst has excellent bifunctional catalytic performance.During the OER,when the current density is 10 m A cm^-2 and the overpotential attain to 0.331 V,which is even better than the commercial Ru O₂.What’s more,its half potential is 0.810 V,which is comparable to 0.82 V of commercial Pt/C.Because of its good bifunctional catalytic performance,its practical application was evaluated.Therefore,a rechargeable Zn-Air battery has been constructed using it as the electrocatalysts.Then,its charge-discharge properties and stability in the long time were evaluated.It can be concluded that,the catalyst shows great catalytic performance,which is even better than the mixture of commercial Pt/C and Ru O₂ and it has good application prospects.2.This work use a facial method to produce the single atom catalyst to catalyst the ORR.The ORR catalytic performance of the catalyst is still far from that of the commercial Pt/C catalyst.Therefore,the synthesis conditions need to be further change to improve its catalytic performance.3.Through a simple one-step calcining process to produce the catalyst,which has excellent catalytic performance.Potassium ferricyanide as the Fe source and N source and the polyethylenimine was used to be the N source and cationic binder.The interaction between iron oxide particles and carbon materials containing the Fe-N-C bond was studied to optimize the electrocatalytic ORR performance and accelerate the occurrence of catalytic reaction.After analyzed the catalytic performance of the catalyst,it can be concluded that this catalyst has excellent ORR catalytic performance.Its half-wave potential is 0.85 V（E1/2≈0.85 V vs reversible hydrogen electrode,RHE）,which is much higher than the commercial Pt/C(E_1/2≈0.82 V).Therefore,it can be concluded that the interaction between iron oxide particles and carbon materials containing Fe-N-C bond has great positive effect on the electrocatalytic ORR,moreover,the preparation method is also applicable to the preparation of other catalysts.