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Hard carbon has attracted great attention for energy storage owing to low cost and extremely high microporosity, however, hindered by its low electrical conductivity. The common strategy to improve the conductivity is through graphitization process which requires temperatures as high as 3000 °C and inevitably destroys the porous structure. Herein, a balance between the specific surface area and electrical conductivity in a 3D porous hard carbon by in situ iron‐catalyzed graphitization process together with the Si–O–Si network is successfully achieved. The Fe can accelerate the localized graphitization at relatively low temperature (1000 °C) to form nanographite domains with enhanced conductivity, while the Si–O–Si network contributes to generating a 3D porous structure. As a result, the optimized hard carbon exhibits a 3D interconnected and hierarchical porous structure with extremely high specific surface area (2075 m2 g−1) and excellent electrical conductivity (12 S cm−1) which is comparable with that of artificial graphite. And thus, high capacitance of 315 F g−1 and excellent rate capability (174 F g−1 at 40 A g−1) are simultaneously achieved when used as electrodes for supercapacitors. The strategy is promising to build hard carbon materials with well‐tuned properties for high‐performance energy storage. [ABSTRACT FROM AUTHOR]

Suppressing the Pt dissolution still remains a big challenge in improving the long‐term stability of Pt‐based catalysts in electrochemical energy conversion. In this work, the degradation of Pt nanoparticles is successfully suppressed via weakening the Pt–O dipole effect by adjusting the electronic structure of surface Pt atoms. The specially designed graphitic‐N‐doped carbon nanosheets with balanced N content and graphitization degree as well as fewer defects are prepared for anchoring Pt nanoparticles to enhance the electronic metal–support interaction. This can accelerate the electron transfer from Pt to substrate, decrease the surface electron density of Pt, and attenuate the Pt–O interaction. As a result, the rate of Pt dissolution decreases by 95% compared to that of commercial Pt/C toward the oxygen reduction reaction and thus the catalytic stability is significantly improved in the electrochemical accelerated durability test. The theoretical simulation shows that the inhibition of surface Pt dissolution is attributed to the enhanced energy barrier in the initial relaxation process. [ABSTRACT FROM AUTHOR]

Large surface area, high conductivity, and rich active site of carbon electrode materials are necessary characteristics for energy storage devices. However, high conductivity and high nitrogen doping of carbon electrode materials are difficult to coordinate. Here, a facile method via the carbonization of nitrogen‐containing Schiff base polymer has been developed to prepare high conductivity and high nitrogen‐doped hierarchical porous carbon. The organic components with a benzene ring structure in the polymer promote the formation of more sp2‐graphitized carbon, which is beneficial for the improvement of electrical conductivity. Nitrogen‐doped hierarchical porous carbon calcined at 900°C under the NH3 atmosphere possesses high nitrogen content of 7.48 at%, a large specific surface area of 1613.2 m2/g, and high electrical conductivity of 2.7 S/cm. As electrode materials in an aqueous‐based supercapacitor, nitrogen‐doped hierarchical porous carbon exhibits superior specific capacitance of 385 F/g at 1 A/g as well as excellent rate performance (242 and 215 F/g at a current density of 100 and 200 A/g, respectively). In addition, the specific capacitance of electrode measured in a two‐electrode system is 335 F/g at 1 A/g, and the long‐term cycling stability can be achieved with more than 94% initial capacitance after 10 000 cycles. The constructed symmetric supercapacitor delivers high energy density and high power density. The outstanding electrochemical performances combined with the novel and scalable synthetic approach make the nitrogen‐doped hierarchical porous carbon potential electrode material for electrochemical devices. [ABSTRACT FROM AUTHOR]

Highly conductive and nitrogen‐rich carbon materials have broad application prospects in energy storage, yet they are somehow contradictory because good conductivity requires high‐temperature heat treatment, which decomposes most nitrogen species. Herein, a novel approach to synthesize a nitrogen‐rich and highly conductive carbon material with extraordinary capacitance through a two‐step nitrogen‐fixation sol–gel method is reported. The process benefits from the coordination of Zn2+ with nitrogen atoms in the precursor sol and the stabilizing bonding between silicon and nitrogen during high‐temperature chemical vapor deposition. The final product shows a high nitrogen content of 5.6 at%, a hierarchical porous structure with a high specific surface area (1610 m2 g−1), and an extraordinary conductivity (23 S cm−1), which enables an impressive capacitance of 380 F g−1. This nitrogen‐fixing method starting with a composite sol–gel may offer a reliable route to the preparation of high‐performance supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]