Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation.Activated carbon as one of the most important adsorbents is tried to be d...Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation.Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its＂Textural Characteristics＂and＂Surface Chemistry＂.These two terms,coupled with each other,are responsible for behavior of activated carbon in adsorption processes and in catalytic applications.Although as-prepared activated carbons are usually nonselective and their surfaces suffer from lack of enough reactive groups,their different aspects may be improved and developed by diverse types of modifications.Oxidation is one of the most conventional modifications used for activated carbons.It may be used as a final modification or as a pre-modification followed by further treatment.In this paper,methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.展开更多
Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. However, activated carbons are conventionally made from fossil ...Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. However, activated carbons are conventionally made from fossil precursors, such as coal and petroleum, which are limited resources and easily aggregate large block in high temperature carbonization processes. In this novel work, we examined the use of rice straw as a potential alternative carbon source precursor for the production of graphene-like active carbon. A very slack activated carbon with ultra-thin two-dimensional （2D） layer structure was prepared by our proposed approach in this work, which includes a pre-treatment process and potassium hydroxide activation at high temperatures. The obtained active carbon derived from rice straw exhibited a capacitance of 255 Fig at 0.5 A/g, excellent rate capability, and long cycling capability （98% after 10,000 cycles）.展开更多
The electrochemical storage of energy in a special kind of active carbon materials used as capacitor electrodes is considered. Petroleum coke was used for preparation of carbons with different porosities by KOH and va...The electrochemical storage of energy in a special kind of active carbon materials used as capacitor electrodes is considered. Petroleum coke was used for preparation of carbons with different porosities by KOH and vapor etching with catalysis of FeCI3 in turn. Carbon electrodes were fabricated and used as electrodes of double layer capacitors. Nitrogen adsorption was used to characterize the porous structure of the carbons. The electrochemical performance of the capacitors in 6 mol/L KOH was investigated with constant current charge and discharge experiments. A specific capacitance larger than 160 F/g was achieved with an electrode composed of 75% active carbon with a specific surface area of 1180 m2/g and 20% graphite as conductive agent. Evaluation of capacitor performance was conducted by different techniques, e.g. voltammetry and impedance spectroscopy. Characteristics of the capacitor were also discussed. A hybrid power source consisting of nickel- hydrogen and double layer capacitor was demonstrated by powering successfully a simulated power load encountered in communication equipment.展开更多
Nitrogen-containing carbons were prepared by modification of activated carbons.The modified carbons were used as electrode materials with improved electrochemical performance.Precursor anthracite was activated by KOH(...Nitrogen-containing carbons were prepared by modification of activated carbons.The modified carbons were used as electrode materials with improved electrochemical performance.Precursor anthracite was activated by KOH(KOH:anthracite= 1:1), modified by melamine or urea and then treated at 1173 K to obtain the modified carbons.The porous structure, the chemical composition and the electrochemical characteristics of the carbons were investigated by nitrogen sorption, XPS and electrochemical methods respectively.Electrochemical experiments were performed in an organic electrolytic solution of 1 M(C2H5)4NBF4/PC.The samples modified by the different methods showed differences in chemical composition that introduced varying degrees of electrochemical performance enhancement.The presence of nitrogen enhanced the electron donor properties and the surface wettability of the activated carbons:this ensured a sufficient utilization of the exposed surface for charge storage.展开更多
A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material charac...A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m2/g and 0.308 4 cm3/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance.展开更多
As the quantity of waste tires increases,more pyrolysis carbon black(CBp),a type of low value-added carbon black,is being produced.However,the application of CBp has been limited.Therefore,it is necessary to identify ...As the quantity of waste tires increases,more pyrolysis carbon black(CBp),a type of low value-added carbon black,is being produced.However,the application of CBp has been limited.Therefore,it is necessary to identify and expand applications of CBp.This work focuses on the preparation of activated carbon(AC)from CBp using the physicochemical activation of carbon dioxide(CO_(2))and potassium hydroxide(KOH).Thereafter,AC is applied to the electrode of the electrical double-layer capacitor(EDLC).The AC prepared by CO_(2)/KOH activation exhibited a hierarchical pore structure.The specific surface area increased from 415 to 733 m^(2)g^(−1),and in combination with low ash content of 1.51%,ensured abundant ion diffusion channels and active sites to store charge.The EDLC comprising the AC(AC-2)electrode prepared by excitation of CO_(2)(300 sccm)and KOH had a reasonable gravimetric specific capacitance of 192 F g^(−1)at 0.5 A g^(−1),and exhibited a good rate capability of 73%at 50 A g^(−1)in a three-electrode system.Moreover,the EDLC device comprising the AC-2 electrode delivered excellent cycling stability(capacitance retention of 106%after 10000 cycles at 2 A g^(−1)in a two-electrode system).Furthermore,a symmetric supercapacitor based on an AC electrode that exhibits a supreme energy density of 4.7 Wh kg^(−1)and a maximum power density of 6362.6 W kg^(−1)is demonstrated.展开更多
文摘Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards oxidation.Activated carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its＂Textural Characteristics＂and＂Surface Chemistry＂.These two terms,coupled with each other,are responsible for behavior of activated carbon in adsorption processes and in catalytic applications.Although as-prepared activated carbons are usually nonselective and their surfaces suffer from lack of enough reactive groups,their different aspects may be improved and developed by diverse types of modifications.Oxidation is one of the most conventional modifications used for activated carbons.It may be used as a final modification or as a pre-modification followed by further treatment.In this paper,methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.
基金financially supported by the Fundamental Research Funds for the Central Universities(Nos.XDJK2017D003,XDJK2017B055)the Program for Excellent Talents in Chongqing(No.102060-20600218)+1 种基金the Program for Innovation Team Building at Institutions of Higher Education in Chongqing(No.CXTDX201601011)the Chinese Government Scholarship(No.2016AUN032)
文摘Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. However, activated carbons are conventionally made from fossil precursors, such as coal and petroleum, which are limited resources and easily aggregate large block in high temperature carbonization processes. In this novel work, we examined the use of rice straw as a potential alternative carbon source precursor for the production of graphene-like active carbon. A very slack activated carbon with ultra-thin two-dimensional （2D） layer structure was prepared by our proposed approach in this work, which includes a pre-treatment process and potassium hydroxide activation at high temperatures. The obtained active carbon derived from rice straw exhibited a capacitance of 255 Fig at 0.5 A/g, excellent rate capability, and long cycling capability （98% after 10,000 cycles）.
基金The authors greatly acknowledge financial support from the National Natural Science Foundation of China(No.59807001).
文摘The electrochemical storage of energy in a special kind of active carbon materials used as capacitor electrodes is considered. Petroleum coke was used for preparation of carbons with different porosities by KOH and vapor etching with catalysis of FeCI3 in turn. Carbon electrodes were fabricated and used as electrodes of double layer capacitors. Nitrogen adsorption was used to characterize the porous structure of the carbons. The electrochemical performance of the capacitors in 6 mol/L KOH was investigated with constant current charge and discharge experiments. A specific capacitance larger than 160 F/g was achieved with an electrode composed of 75% active carbon with a specific surface area of 1180 m2/g and 20% graphite as conductive agent. Evaluation of capacitor performance was conducted by different techniques, e.g. voltammetry and impedance spectroscopy. Characteristics of the capacitor were also discussed. A hybrid power source consisting of nickel- hydrogen and double layer capacitor was demonstrated by powering successfully a simulated power load encountered in communication equipment.
基金Projects 50672025 and 50730003 supported by the National Natural Science Foundation of China
文摘Nitrogen-containing carbons were prepared by modification of activated carbons.The modified carbons were used as electrode materials with improved electrochemical performance.Precursor anthracite was activated by KOH(KOH:anthracite= 1:1), modified by melamine or urea and then treated at 1173 K to obtain the modified carbons.The porous structure, the chemical composition and the electrochemical characteristics of the carbons were investigated by nitrogen sorption, XPS and electrochemical methods respectively.Electrochemical experiments were performed in an organic electrolytic solution of 1 M(C2H5)4NBF4/PC.The samples modified by the different methods showed differences in chemical composition that introduced varying degrees of electrochemical performance enhancement.The presence of nitrogen enhanced the electron donor properties and the surface wettability of the activated carbons:this ensured a sufficient utilization of the exposed surface for charge storage.
基金Project(2007BAE12B01) supported by the National Key Technology Research and Development Program of China
文摘A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m2/g and 0.308 4 cm3/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance.
基金supported by the National Natural Science Foundation of China (Grant No. 12175089)the National Key Research and Development Program of China (Grant No. 2019YFC1907900)+4 种基金the Key Research and Development Program of Yunnan Province (Grant No. 202103AF140006)the Applied Basic Research Programs of Yunnan Provincial Science and Technology Department (Grant No. 202001AW070004)the Freely Exploring Fund for Academicians in Yunnan Province (Grant No.202005AA160008)the Key Laboratory of Resource Chemistry,Ministry of Education (Grant No. KLRC_ME2001)the Applied Basic Research Programs of Sichuan Provincial Science and Technology Department(Grant No. 2021yj0007)
文摘As the quantity of waste tires increases,more pyrolysis carbon black(CBp),a type of low value-added carbon black,is being produced.However,the application of CBp has been limited.Therefore,it is necessary to identify and expand applications of CBp.This work focuses on the preparation of activated carbon(AC)from CBp using the physicochemical activation of carbon dioxide(CO_(2))and potassium hydroxide(KOH).Thereafter,AC is applied to the electrode of the electrical double-layer capacitor(EDLC).The AC prepared by CO_(2)/KOH activation exhibited a hierarchical pore structure.The specific surface area increased from 415 to 733 m^(2)g^(−1),and in combination with low ash content of 1.51%,ensured abundant ion diffusion channels and active sites to store charge.The EDLC comprising the AC(AC-2)electrode prepared by excitation of CO_(2)(300 sccm)and KOH had a reasonable gravimetric specific capacitance of 192 F g^(−1)at 0.5 A g^(−1),and exhibited a good rate capability of 73%at 50 A g^(−1)in a three-electrode system.Moreover,the EDLC device comprising the AC-2 electrode delivered excellent cycling stability(capacitance retention of 106%after 10000 cycles at 2 A g^(−1)in a two-electrode system).Furthermore,a symmetric supercapacitor based on an AC electrode that exhibits a supreme energy density of 4.7 Wh kg^(−1)and a maximum power density of 6362.6 W kg^(−1)is demonstrated.
