Electrosorption capacitance of nanostructured carbon-based materials.
The fundamental mechanism of electrosorption of ions developing a double layer inside nanopores was studied via a combination of experimental and theoretical studies. A novel graphitized-carbon monolithic material has proven to be a good electrical double-layer capacitor that can be applied in the separation of ions from aqueous solutions. An extended electrical double-layer model indicated that the pore size distribution plays a key role in determining the double-layer capacitance in an electrosorption process. Because of the occurrence of double-layer overlapping in narrow pores, mesopores and micropores make significantly different contributions to the double-layer capacitance. Mesopores show good electrochemical accessibility. Micropores present a slow mass transfer of ions and a considerable loss of double-layer capacitance, associated with a shallow potential distribution inside pores. The formation of the diffuse layer inside the micropores determines the magnitude of the double-layer capacitance at low electrolyte concentrations and at conditions close to the point of zero charge of the material. The effect of the double-layer overlapping on the electrosorption capacitance can be reduced by increasing the pore size, electrolyte concentration, and applied potential. The results are relevant to water deionization.
Hou
Chia-Hung
CH
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0373, USA.
Liang
Chengdu
C
Yiacoumi
Sotira
S
Dai
Sheng
S
Tsouris
Costas
C
D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D025802:Electric Capacitance; D004563:Electrochemistry; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
D002244:Carbon