Study of Synthesis,Wettability and Application of Porous Carbon Materials

Author:Jiao Yuan

Supervisor:wang ai ying

Database:Doctor

Degree Year:2017

Download:52

Pages:131

Size:9905K

Keyword:

Porous carbon materials refer to carbon materials with porous structures,which give them high space ratio and surface area.Since carbon materials are abundant,easy to be obtained,and possible to connect with other atoms through different hybridization,thus gaining electrical and thermal conductivity,chemical and physical stability,they have promising future in various fields.However,since diamond has a mild hydrophilic surface while graphite has a mild hydrophobic surface,carbon materials show limit changes in wettability.To obtain carbon materials with wettability changing in a larger range,both plasma enhanced chemical vapor deposition(PECVD)and dual-templating methods have been adopted to synthesize porous carbon materials in this thesis.When using PECVD for porous carbon material synthesis,plasma has been used for polymer surface treatment,including etching and deposition of amorphous carbon film;through alternating deposition pressure,porous carbon materials have been synthesized.More important,dual-templating has also been successfully developed for another kind of porous carbon material,where the wettability of porous carbon materials has been focused,and the related applications have also been explored.PECVD is one of the widely used deposition method for amorphous carbon films.Here,we used PECVD to deposit both amorphous carbon film and porous carbon materials.Their wettability,thermal stability and formation mechanism have also been studied.The results showed that different from dense and smooth amorphous carbon films formed in high vacuum system,when deposition pressure increased from 100 mTorr to 300 mTorr,the materials’ morphology changed from stacked plates into porous network formed by round particles connecting each other.Since air can fill in the space in porous structure and then repel water,the porous carbon materials show good hydrophobicity.Meanwhile,the materials are oleophilic,which gives the material potential in oil-water separation.When heated and cooled between 340 oC to 380 oC,this porous material’s surface composition appeared to be reversibly changing between two different states.The formation mechanism of porous carbon materials has been explored by adding an extra electrode,forming two anodes or cathodes in the deposition system.The high deposition pressure leads to more collision among particles,decreasing their kinetic energy so that they cannot hit the deposited surface.Instead,low-energy particles attached and gathered with each other,forming porous structure.For more adjustable porous structure,dual-templating strategy has been used to synthesize porous carbon materials with macro-meso hierarchical structure as well.Wettability and conductivity of the fabricated porous carbon materials have been studied.When using PET fabric as hard template,block polymer F127 as soft template,phenolic resol as carbon precursor,hierarchical porous carbon materials have been produced.Pore dispersion and size of meso-pores could be adjusted by changing the ratio of phenolic resol to F127;conductivity could be adjusted by different carbonization duration and temperature.It has been discovered that this kind of porous carbon materials has superhydrophilicity which can last for long time even when kept under ambient atmosphere.Carbonized phenolic resol is hydrophilic,and the macropores from the decomposition of PET fabrics acts as passageway for water,the synergy of the composition and structure leads to the long-last superhydrophilicty.Through different carbonization duration and temperature,porous carbon materials with different conductivity have been synthesized and showed different application as battery electrode or liquid concentration detection.Those have better conductivity have been used as battery electrodes,and showed high capacity because of the high surface area;those have less conductivity have shown promising future in liquid concentration detection,and the high surface area helps to get a better sensitivity.This dual-templating method has been extended to many different hard templates,including plants which are abundant in nature,all succeeded in synthesizing superhydrophilic and conductive hierarchical porous carbon materials,showing wide applicability.