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Carbon materials have become a focal point in supercapacitors (SCs) due to their perfect charge–discharge behavior, relatively low cost, and excellent electrochemical stability, but the limited electrochemical activity restricts their further development. MXenes (Ti3C2Tx) combine high electrical conductivity, hydrophilicity, and abundance surface functional groups, which contribute to high energy density when compounded with carbon materials. In this work, carbon material derived from mineral water bottles is modified with cetyltrimethylammonium bromide (CTAB) that spontaneously forms into porous heterogeneous structures with Ti3C2Tx under electrostatic interactions. The carbon material hinders the reaggregation of Ti3C2Tx, while Ti3C2Tx increases the electrochemical activity on the surface of the carbon material. A hierarchical porous carbon with a large specific surface area of 1754.3 m2 g−1, promoting the electrolyte migration kinetics and high specific capacitance in 6 m KOH electrolyte (404.1 F g−1 at 1 A g−1). The symmetric SC made as‐prepared carbon electrode shows an extended voltage window (1.8 V), an optimal energy density (31.19 Wh kg−1 at a power density of 450 W kg−1) and a low capacitance decay (1% after 15 000 cycles) in 1.5 m Na2SO4. The preparation of electrode material with a unique structure provides a practical and innovative strategy for the value‐added utilization of waste plastics. [ABSTRACT FROM AUTHOR]

Achieving high rate capability of porous carbon at high mass loading is important for developing advanced supercapacitors. But it still remains a big challenge because thick electrode causes severely reduced electric conductivity and blocked ion migration channels. Herein, we develop a micelle-induced assembly method to prepare conductive porous carbon through puzzling flexible graphene quantum dots (GQDs). The unique sp2 hybridized GQDs ensure the product with a two times higher electric conductivity than the commercial activated carbon. The interconnected mesoporous structure promotes robust ion transport kinetics especially at high mass loadings. As supercapacitor electrode, it shows high capacitances of 315 and 170 F g−1 at 1 and 100 A g−1, respectively. Importantly, at a very high mass loading of 20 mg cm−2, it shows a remarkably high areal capacitances of 2.8 F cm−2 at 10 A g−1, which is much better than other reported carbon materials. The symmetric supercapacitors show maximum energy densities of 9.21 and 6.45 Wh kg−1 at the mass loadings of 2 mg cm−2 and 20 mg cm−2, respectively, revealing the structural advantage of GQD-puzzled porous carbon for practical applications. Conductive porous carbon prepared by micelle-induced assembly of graphene quantum dots shows high capacitive and rate performance at high mass loadings due to sufficient ion and electron transport paths. Image 1 • Porous carbon with high conductivity was prepared using the sp2 hybridized GQDs. • Sufficient electron/ion transport paths enable robust electrochemical kinetics. • The sample shows remarkable rate performance especially at high mass loadings. [ABSTRACT FROM AUTHOR]

To satisfy the practical needs of the sustainability and industrialization of supercapacitors, it is essential to maintain good electrochemical performance at high mass loading above the commercial levels (10 mg cm−2). Herein, a unique 3D porous carbon with high mass loading is successfully prepared from Linum usitatissimum L. stem via a simple route of high temperature carbonization and subsequent KOH activation. The as-prepared porous carbon displays rich N/O heteroatoms, hierarchical porous, and interconnected vertical channels, which enable fast electron/ion transport and afford additional capacitance. These characteristics give the resultant carbon high capacitances of 434/245 F g−1 at 1/50 A g−1. Importantly, the as-prepared carbon can achieve mass loadings of 20 mg cm−2 and maintain decent electrochemical performance at this mass loadings, owing to short electron/ion transfer pathway as well as sufficient active sites. Specifically, the assembled symmetric supercapacitor delivers superior areal capacitance of 3.7 F cm−1 at 1 A g−1 and remarkably capacitance retention of 2.5 F cm−1 at 5 A g−1 under 20 mg cm−1. This work enlightens a sustainable and facile way for constructure advanced electrode material. • Porous carbon was facilely prepared from Linum usitatissimum L. stem. • N/O atoms provide sufficient active sites for high mass loading electrode. • LUC-800 exhibits high capacitances of 434 F g−1 at 1 A g−1. • LUC-800 still delivers a high energy density at 20 mg cm−2. • This work provides a promising approach for utilization of agricultural waste. [ABSTRACT FROM AUTHOR]

The development of materials that can be applied to high-energy-density supercapacitors and high-efficiency adsorbents remains challenging. In this paper, a novel walnut shell-derived porous carbon (WSC) decorated bimetallic sulfide (Co/Zn-S@WSC) composite was successfully fabricated by a facile high-temperature alkaline activation and vulcanization strategy. The WSC with a three-dimensional (3D) porous structure plays the role of a "skeleton" during the preparation and growth of the composite, allowing the metal-organic framework (MOF) derived sulfides Co/Zn-S to be distributed evenly across the 3D framework of porous carbon. The prepared Co/Zn-S@WSC demonstrates a multi-level pore structure, which reduces ion transport paths and facilitates energy storage, thus the electrochemical properties of the electrode are enhanced efficiently. The electrode samples were tested in a 6 mol/L KOH electrolyte. Co/Zn-S@WSC presents a specific capacitance of 987.2 F·g−1 at a current density of 1 A·g−1. In addition, an asymmetric supercapacitor (ASC), using Co/Zn-S@WSC (positive electrode) and WSC (negative electrode), shows a high energy density of 42.59 Wh·kg−1 at a power density of 374.88 W·kg−1 and cycling stability with 92% capacity retention after 10,000 cycles. Benefiting from a rational hierarchical pore structure, Co/Zn-S@WSC exhibits the promising adsorption capibilities for methylene blue (MB). A simple, efficient, and practical method for the development and application of novel multifunctional materials is provided by this work. [Display omitted] • A novel WSC decorated Co/Zn-S composite (Co/Zn-S@WSC) was successfully fabricated. • The Co/Zn-S@WSC composite forms the multi-level pore structure. • ASC shows excellent cycling stability with 92% capacity retention after 10,000 cycles. • Co/Zn-S@WSC composite also exhibits the promising adsorption of MB. [ABSTRACT FROM AUTHOR]