| Graphite phase carbon nitride can be used as an ideal carrier material for noble metal nanoparticles based on its wide sources,low cost and easy preparation,and rich in N active sites in six membered ring structure.However,the application of carbon nitride in oxygen reduction electrocatalytic reaction is seriously restricted due to its small specific surface area and low conductivity,which is not benefit to the application in the field of energy.Therefore,this paper focuses on the problems of low conductivity and slow reaction kinetics of carbon nitride in oxygen reduction reaction.The research is carried out from the interface scale and different dimensional structure design.The research is mainly carried out as follows:(1)Based on the metal carrier interface interaction,platinum nanoparticles were intercalated into graphite phase carbon nitride by gamma irradiation to construct carbon nitride/platinum electron transport channel.The metal nanoparticles grew into spherical particles with the minimum free energy and were uniformly distributed on the surface of the carbon nitride with the radiation dose of 140 k Gy.At this time,the material has a good metal carrier interface and the best electrocatalytic activity.The half-wave potential was 0.816 V and the limit current density reached 5.56 m A·cm-2.(2)Based on the research foundation of gamma irradiation technology in the previous chapter,3D structure engineering design was introduced.A polar solvent dimethyl sulfoxide was used to control the size and morphology of carbon nitride to improve the available specific surface area of carbon nitride.Then,carbon black with good conductivity and nuclear positive charge functionalization was introduced to form a three-dimensional cross-linked spherical shape with carbon nitride based on electrostatic self-assembly.Finally,metal was supported on the surface of carbon nitride by gamma ray.The nitrogen-containing active sites on the surface of graphite phase carbon nitride and the micelles on the surface of carbon black can well anchor platinum nanoparticles and prevent noble metal agglomeration.A three-dimensional Spherical shape structure was prepared and its oxygen reduction performance was studied.Among them,the catalyst exhibited a high initial potential of 0.93 V.The calculation results show that the catalyst has high selectivity for four electron reaction,stable three-dimensional spherical shape structure,reliable cycle stability and excellent methanol toxicity resistance.(3)Then the effect of low-dimensional structure engineering on the reduction performance of carbon nitride was explored.The carbon nitride was exfoliated into carbon nitride nanosheets,then polymerization with pyrrole monomer,the mixture was pyrolyzed at high temperature.The conjugated carbon materials were introduced to carbon nitride for enhancing the electron transport rate.Meanwhile,more active sites of metal were introduced into the composite by gamma irradiation,and then study the catalytic performance of the structure for oxygen reduction.The limiting current density of one dimensional hollow tubular carbon nitride is 6.9 m A·cm-2,the experimental data show that the hollow tubular structure can weaken the electron transfer resistance,accelerate the transmission and diffusion of oxygen and electrolyte,provide abundant active sites for the conversion of oxygen molecules,significantly reduce the reaction energy barrier,and improve the electrocatalytic activity.To sum up,this paper study the structural design of carbon-based electrocatalysts,and provide certain theoretical basis and technical support for material research in the field of energy. |
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