Kroll-carbons based on silica and alumina templates as high-rate electrode materials in electrochemical double-layer capacitors

Hierarchical Kroll-carbons (KCs) with combined micro- and mesopore systems are prepared from silica and alumina templates by a reductive carbochlorination reaction of fumed silica and alumina nanoparticles inside a dense carbon matrix. The resulting KCs offer specific surface areas close to 2000 m2 g−1 and total pore volumes exceeding 3 cm3 g−1, resulting from their hierarchical pore structure. High micropore volumes of 0.39 cm3 g−1 are achieved in alumina-based KCs due to the enhanced carbon etching reaction being mainly responsible for the evolution of porosity. Mesopore sizes are uniform and precisely controllable over a wide range by the template particle dimensions. The possibility of directly recycling the process exhaust gases for the template synthesis and the use of renewable carbohydrates as the carbon source lead to a scalable and efficient alternative to classical hard- and soft templating approaches for the production of mesoporous and hierarchical carbon materials. Silica- and alumina-based Kroll-carbons are versatile electrode materials in electrochemical double-layer capacitors (EDLCs). Specific capacitances of up to 135 F g−1 in an aqueous electrolyte (1 M sulfuric acid) and 174 F g−1 in ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are achieved when measured in a symmetric cell configuration up to voltages of 0.6 and 2.5 V, respectively. 90% of the capacitance can be utilized at high current densities (20 A g−1) and room temperature rendering Kroll-carbons as attractive materials for EDLC electrodes resulting in high capacities and high rate performance due to the combined presence of micro- and mesopores

Kroll-carbons based on silica and alumina templates as high-rate electrode materials in electrochemical double-layer capacitors

Hierarchical Kroll-carbons (KCs) with combined micro- and mesopore systems are prepared from silica and alumina templates by a reductive carbochlorination reaction of fumed silica and alumina nanoparticles inside a dense carbon matrix. The resulting KCs offer specific surface areas close to 2000 m2 g-1 and total pore volumes exceeding 3 cm3 g-1,} resulting from their hierarchical pore structure. High micropore volumes of 0.39 cm3 g-1 are achieved in alumina-based KCs due to the enhanced carbon etching reaction being mainly responsible for the evolution of porosity. Mesopore sizes are uniform and precisely controllable over a wide range by the template particle dimensions. The possibility of directly recycling the process exhaust gases for the template synthesis and the use of renewable carbohydrates as the carbon source lead to a scalable and efficient alternative to classical hard- and soft templating approaches for the production of mesoporous and hierarchical carbon materials. Silica- and alumina-based Kroll-carbons are versatile electrode materials in electrochemical double-layer capacitors (EDLCs). Specific capacitances of up to 135 F g-1 in an aqueous electrolyte (1 M sulfuric acid) and 174 F g-1 in ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are achieved when measured in a symmetric cell configuration up to voltages of 0.6 and 2.5 V{, respectively. 90 of the capacitance can be utilized at high current densities (20 A g-1) and room temperature rendering Kroll-carbons as attractive materials for EDLC electrodes resulting in high capacities and high rate performance due to the combined presence of micro- and mesopores

ZnPd/ZnO Aerogels as Potential Catalytic Materials

Many different aerogel materials are known to be accessible via the controlled destabilization of the respective nanoparticle suspensions. Especially for applications in heterogeneous catalysis such materials with high specific surface areas are highly desirable. Here, a facile method to obtain a mixed ZnPd/ZnO aerogel via a reductive treatment of a preformed Pd/ZnO aerogel is presented. Different morphologies of the Pd/ZnO aerogels could be achieved by controlling the destabilization of the ZnO sol. All aerogels show a high CO2 selectivity of up to 96% and a very good activity in methanol steam reforming that delivers hydrogen, which is one of the most important fuels for future energy concepts. The method presented is promising for different transition metal/metal oxide systems and hence opens a path to a huge variety of materials

Kroll-carbons based on silica and alumina templates as high-rate electrode materials in electrochemical double-layer capacitors

Hierarchical Kroll-carbons (KCs) with combined micro- and mesopore systems are prepared from silica and alumina templates by a reductive carbochlorination reaction of fumed silica and alumina nanoparticles inside a dense carbon matrix. The resulting KCs offer specific surface areas close to 2000 m2 g−1 and total pore volumes exceeding 3 cm3 g−1, resulting from their hierarchical pore structure. High micropore volumes of 0.39 cm3 g−1 are achieved in alumina-based KCs due to the enhanced carbon etching reaction being mainly responsible for the evolution of porosity. Mesopore sizes are uniform and precisely controllable over a wide range by the template particle dimensions. The possibility of directly recycling the process exhaust gases for the template synthesis and the use of renewable carbohydrates as the carbon source lead to a scalable and efficient alternative to classical hard- and soft templating approaches for the production of mesoporous and hierarchical carbon materials. Silica- and alumina-based Kroll-carbons are versatile electrode materials in electrochemical double-layer capacitors (EDLCs). Specific capacitances of up to 135 F g−1 in an aqueous electrolyte (1 M sulfuric acid) and 174 F g−1 in ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are achieved when measured in a symmetric cell configuration up to voltages of 0.6 and 2.5 V, respectively. 90% of the capacitance can be utilized at high current densities (20 A g−1) and room temperature rendering Kroll-carbons as attractive materials for EDLC electrodes resulting in high capacities and high rate performance due to the combined presence of micro- and mesopores

Kroll-carbons based on silica and alumina templates as high-rate electrode materials in electrochemical double-layer capacitors

Hierarchical Kroll-carbons (KCs) with combined micro- and mesopore systems are prepared from silica and alumina templates by a reductive carbochlorination reaction of fumed silica and alumina nanoparticles inside a dense carbon matrix. The resulting KCs offer specific surface areas close to 2000 m2 g−1 and total pore volumes exceeding 3 cm3 g−1, resulting from their hierarchical pore structure. High micropore volumes of 0.39 cm3 g−1 are achieved in alumina-based KCs due to the enhanced carbon etching reaction being mainly responsible for the evolution of porosity. Mesopore sizes are uniform and precisely controllable over a wide range by the template particle dimensions. The possibility of directly recycling the process exhaust gases for the template synthesis and the use of renewable carbohydrates as the carbon source lead to a scalable and efficient alternative to classical hard- and soft templating approaches for the production of mesoporous and hierarchical carbon materials. Silica- and alumina-based Kroll-carbons are versatile electrode materials in electrochemical double-layer capacitors (EDLCs). Specific capacitances of up to 135 F g−1 in an aqueous electrolyte (1 M sulfuric acid) and 174 F g−1 in ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are achieved when measured in a symmetric cell configuration up to voltages of 0.6 and 2.5 V, respectively. 90% of the capacitance can be utilized at high current densities (20 A g−1) and room temperature rendering Kroll-carbons as attractive materials for EDLC electrodes resulting in high capacities and high rate performance due to the combined presence of micro- and mesopores