Search

[Display omitted] • Electrochemically active Oxygen doped carbon (O-PCNs) was fabricated by superbase templated method. • The template basicity on the functionalities and the supercapacitor performances of the derived O-PCNs were disclosed. • The O-PCN-20 is rich in porosity, large in surface area (930 m2/g) and high in active oxygen content (11.4 atom%). • · The O-PCN-20 electrode exhibits large capacitance of 375 F/g@1.0 A/g and energy density of 25.7 Wh/kg@900 W/kg. Templating techniques have been widely adopted for the synthesis of porous carbons, such as oxygen-doped porous carbon nanosheets (O-PCNs), but the effect of the surface characteristics of templates on the surface functionality and performance of a derived carbon has not been well studied. Herein, a series of laboratory-made superbases of K/Mg(OH) 2 with different K/Mg ratios were employed as template to fabricate nanocarbon materials. The aim is to find out how the strength of template basicity could influence the surface functionalities and the supercapacitor performances of the derived O-PCNs. The resulting materials are rich in conjugated hydroxyl and carbonyl groups that are electrochemically active owing to the protection of the conjugated hydroxyl group by KOH and the dehydrogenation step catalyzed by magnesium oxide. Systematic investigations revealed that with the increase of basic strength, the content of the derived electrochemically active oxygen species in the forms of conjugated carbonyl (C O) and hydroxyl (C OH) first increases from 8.4 atom% to 11.4 atom% then decreases to 9.25 atom%. Moreover, the microporosity of the O-PCNs stepwise increases with the rise of KOH loading, ascribable to the effect of KOH etching on the carbon skeleton. The O-PCN-20 templated by 20 % K/Mg(OH) 2 is rich in porosity, large in surface area (930 m2/g) and high in active oxygen content (11.4 atom%). With high active surface area and extra Faradaic capacitance, O-PCN-20 exhibited superior supercapacitor performances including large specific capacitance of 375 F/g@1.0 A/g, high rate capability of 81.1 % (from 1.0 A/g to 20 A/g), energy density of 25.7 Wh/kg@900 W/kg and excellent cycling stability with near 100 % capacitance retentions after 10 000 cycles and more than 86.2 % capacitance retention over 20 000 cycles at large current density of 10 A/g, indicating O-PCN-20 has potential to be used as electrode material for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • An all-solid-state (ASS) strategy without using any solvents and activators was developed. • The ASS strategy derived carbon owns abundant nitrogen species and large packing density. • The resultant product show superior supercapacitor performances with both high gravimetric and volumetric performances. Template synthesis of porous carbon with rich functionalities by a scalable strategy without using any solvents and activators will be a green and promising route. Herein, we reported an all-solid-state synthesis strategy by mixing glucose and graphitic carbon nitride (g -C 3 N 4) by milling and then undergoing a segmented carbonization in which first at low temperature of 573 K to polymerize sucrose onto g -C 3 N 4 , then at high temperature of 973 K to carbonized the composite to obtain a porous carbon (denoted as GNC) with abundant nitrogen species over 20 atom% and large packing density (0.91–1.25 g cm−3). Due to the features of large packing density and rich electrochemically-active N species, as electrode for supercapacitive energy storage, the developed GNC exhibit a comparable energy storage level with both high gravimetric energy density of 26.8 Wh kg−1@1000 W kg−1 and volumetric energy density of 30.8 Wh L−1@1150 W L−1, suggesting a potentiality in energy storage field. Importantly, the present strategy owns characteristics of ease of operation, green and scalable, which would be a promising synthesis route towards the fabrication of functional carbon utilizing in many fields like sorption & separation, catalysis, energy storage and so on. [ABSTRACT FROM AUTHOR]

As an industrial material for supercapacitive energy storage, commercial activated carbons (AC) could achieve a satisfactory gravimetric performances by electric double layered capacitance (EDLC) due to their rich microporosity, but the volumetric performances are usually poor resulted from the low packing density. Herein, we presented a strategy to address this tradeoff relationship and to achieve both high gravimetric and volumetric performance by filling the macro/mesoporosity with extra nitrogen doped carbon. The reconstructed activated carbon could inherit most of microporosity from the parent AC, while the macro/mesoporosity of them was greatly decreased, resulting in increase of packing density and the improvement of surface hydrophilicity. Benefited from the increase of packing density and maintenance of microporosity, the resultant activated carbon achieves greatly enhanced energy storage level including three times higher capacitance of 384 F cm−3@ 1.0 A/g (vs 128 F cm−3@ 1.0 A/g for pristine AC), high rate capability of 73.4% (vs 59.2% for pristine AC), larger energy density of 27.5 Wh L−1@ 900 W L−1 (vs 10.0 Wh L−1@747 W L−1). Importantly, the present strategy provides a facile and unique method to process activated carbon, which offers a possibility improving the energy storage level of the commercial activated carbon. [Display omitted] • Commercial activated carbon (AC) was processed by filling the macro/mesoporosity. • The filled AC owns increased packing density and more nitrogen functionalities. • The filled AC achieves greatly enhanced supercapacitor performances. [ABSTRACT FROM AUTHOR]