Carbon‐based nanomaterials have been regarded as promising non‐noble metal catalysts for renewable energy conversion system (e.g., fuel cells and metal–air batteries). In general, graphitic skeleton and porous structure are both critical for the performances of carbon‐based catalysts. However, the pursuit of high surface area while maintaining high graphitization degree remains an arduous challenge because of the trade‐off relationship between these two key characteristics. Herein, a simple yet efficient approach is demonstrated to fabricate a class of 2D N‐doped graphitized porous carbon nanosheets (GPCNSs) featuring both high crystallinity and high specific surface area by utilizing amine aromatic organoalkoxysilane as an all‐in‐one precursor and FeCl3·6H2O as an active salt template. The highly porous structure of the as‐obtained GPCNSs is mainly attributed to the alkoxysilane‐derived SiOx nanodomains that function as micro/mesopore templates; meanwhile, the highly crystalline graphitic skeleton is synergistically contributed by the aromatic nucleus of the precursor and FeCl3·6H2O. The unusual integration of graphitic skeleton with porous structure endows GPCNSs with superior catalytic activity and long‐term stability when used as electrocatalysts for oxygen reduction reaction and Zn–air batteries. These findings will shed new light on the facile fabrication of highly porous carbon materials with desired graphitic structure for numerous applications.
Carbonaceous materials are widely investigated as anodes for potassium‐ion batteries (PIBs). However, the inferior rate capability, low areal capacity, and limited working temperature caused by sluggish K‐ions diffusion kinetics are still primary challenges for carbon‐based anodes. Herein, a simple temperature‐programmed co‐pyrolysis strategy is proposed for the efficient synthesis of topologically defective soft carbon (TDSC) based on inexpensive pitch and melamine. The skeletons of TDSC are optimized with shortened graphite‐like microcrystals, enlarged interlayer spacing, and abundant topological defects (e.g., pentagons, heptagons, and octagons), which endow TDSC with fast pseudocapacitive K‐ion intercalation behavior. Meanwhile, micrometer‐sized structure can reduce the electrolyte degradation over particle surface and avoid unnecessary voids, ensuring a high initial Coulombic efficiency as well as high energy density. These synergistic structural advantages contribute to excellent rate capability (116 mA h g−1 at 20 C), impressive areal capacity (1.83 mA h cm−2 with a mass loading of 8.32 mg cm−2), long‐term cycling stability (capacity retention of 91.8% after 1200 h cycling), and low working temperature (−10 °C) of TDSC anodes, demonstrating great potential for the practical application of PIBs.
Heteroatom doping, especially nitrogen doping, has been regarded as an efficient strategy to break through the capacity limitation of carbonaceous anode materials in potassium-ion batteries (PIBs). Constructing edge-nitrogen-rich carbon skeleton with highly exposed active sites and efficient charge transfer is critical for the high performance of nitrogen-doped carbonaceous anode materials. Herein, a kind of ultrahigh edge-nitrogen (up to 16.2 at%) doped carbon nanosheets (ENCNS) has been developed by an efficient assembly of high-nitrogen-ratio melamine (MA) with polyacrylic acid grafted graphene oxide (GO-g-PAA) molecular brushes. The assembled PAA/MA structure facilitates the formation of an edge-nitrogen-rich carbon skeleton during heat treatment, while the highly conductive graphene backbone with a 2D nanomorphology enables shortened ion diffusion pathways and numerous exposed active surfaces. As a result, the ENCNS demonstrate excellent rate performance (up to 144 mAh g−1 at 10 A g−1) and good cycle stability (136 and 100 mAh g−1 after 400 cycles at 5 and 10 A g−1, respectively).
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