Preparation And Application Of Porous Carbon Nano Bowls

Porous carbon nanomaterials(PCNs)have been widely used in various fields such as optics,electronics,biology,medical and other fields due to their unique physical and chemical properties.The morphology,pore structures and pore size of materials have great influence on its properties and stability,for example,the asymmetric morphology of the PCNs as a supercapacitors electrode material can greatly improve the volume of energy density,which is helpful for its practical application in supercapacitors.However,morphology control of PCNs is still a great challenge due to lack of systematic theoretical knowledge.And thus,most of the reported PCNs are usually spherical nanoparticles,and the monodispersed PCNs with asymmetric morphology are rarely reported,because all carbon nanostructures tend to condense and aggregate during the carbonization process.In addition,the reported preparation method is too complex and the yield is too low for scalable preparation of PCNs with asymmetric morphology.Therefore,it is very important to develop a controllable and facile preparation method.In this paper,bowl-like monodispersed porous carbon nanoparticles(BMPCNs)have been successfully prepared with a facile and scalable approach,based on a combination of the Stober process and the assembly process of cetyltrimethylammonium bromide(CTAB)wormlike micelles with silica/resorcinol-formaldehyde oligomers at the interface of tetraethyl orthosilicate(TEOS)droplets.The formation mechanism of BMPCNs has been discussed.In addition,their electrochemical supercapcitve properties were preliminarily investigated.On this foundation,the nitrogen-doped bowl-like monodispersed porous carbon nanoparticles was successfully prepared,and their electrochemical performance was investigated.Further,BMPCNs was used as support to load ZrO2 and SnO2 nanoparticles,and the electrochemical characteristics and adsorption behavior for organic pollutant of the obtained nanocomposite materials were studied.Finally,the preparation method of 50 nm hollow Porous carbon balls have successfully developed and their electrochemical performance was investigated.The detail contents and results are as follows:(1)The resorcinol and formaldehyde were chosen as polymer precursor,TEOS as inorganic precursor and CTAB as both morphology-controlling agent and pore-forming agent,and ammonia solution(NH3.H2O)as pH regulator and water-ethanol as co-solvent.After the processes of sol-gel,hydrothermal reaction,high temperature carbonization and etching SiO2 template,the BMPCNs about 200-300 nm have been successfully prepared.The influences of preparation parameters,such as the concentration of each reactant,ratio of ethanol/H2O,reaction time and so on were discussed.Further,to investigate the bowl shape evolution,time-dependent experiments were carried out and the products collected at different stages.The results show that the bowl-like structure was formed by the simple self-assembly process of CTAB wormlike micelles and SiO2 oligomerization and phenolic resin at the interface of TEOS droplets.Benefiting from the unique features of high surface area(1254.7 m2/g)and a large porosity(1.87 cm3/g),hierarchical pore structure consisting of micropores and mesopores in which 950 °C carbonized sample(W-950),the resultant BMPCNs show a high capacitance(up to 286 F/g at 0.5 A/g),and outstanding cycling stability(94.8%capacity retention after 10000 cycles at 10 A/g)in electrochemical double-layer capacitors,suggesting its promising applications in field of energy conversion and storage.In addition,this method has excellent reproducibility and feasibility for scalable synthesis,the yield of BMPNPs can be stable at 31 g.(2)The nitrogen-doped bowl-like monodispersed porous carbon nanoparticles have been successfully prepared by using melamine as nitrogen source.The effects of carbonization temperature on the morphology,specific surface area,nitrogen content and graphitization degree of the samples were investigated.Their electrochemical performance as electrode material of supercapacitor and electro-catalytic behavior for oxygen reduction reaction(ORR)were measured.The results showed that,the sample carbonized at 750 ? have high surface area(1415.4 m2/g),and the specific capacitance(235 F/g at 0.5 A/g).At the same time,it has shown definite catalytic activity for ORR.(3)To prepare the nanocomposite materials of BMPCNs/ZrO2 and BMPCNs/SnO2,the influence of experiment parameters,such as the kind and concentration of zirconium and tin source,the reaction temperature and time,on the uniformly loading of ZrO2 and SrnO2 nanoparticles at the surface of BMPCNs,was investigate systematically.An optimized experiment condition has been obtained,in which the loading amount,the distribution and the size of ZrO2 and SnO2 nanoparticles are perfectly manageable.Moreover,the nanocomposite of BMPCNs/ZrO2 exhibits good adsorption ability for organic pollutant of Congo red,and the nanocomposite of BMPCNs/SnO2 provided good capacitive performance as electrode materials of supercapacitor.(4)The hollow Porous carbon nanospheres with diameter of 50 nm have successfully prepared by using porous SiO2 nanospheres as template.The influence of synthesis parameters on the distribution and the shell thickness of the hollow Porous carbon nanospheres were investigated,and the electrochemical characterization were measured.