Nitrogen‐Doped Graphitic Porous Carbon Nanosheets Derived from In Situ Formed g‐C<sub>3</sub>N<sub>4</sub> Templates for the Oxygen Reduction Reaction

Chemistry An Asian Journal

et al. 2018

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This study describes a self-doping and additive-free strategy for the synthesis of metal-nitrogen-doped porous carbon materials (CMs) via carbonizing well-tailored precursors, metal-containing ionic liquids (M-ILs). The organic skeleton in M-ILs serves as both carbon and nitrogen sources, while metal ions acts as porogen and metallic dopants. A high nitrogen content, appropriate content of metallic species and hierarchical porosity synergistically endow the resultant CMs (MIBA-M-T) as effective electrocatalysts for the oxygen reduction reaction (ORR). MIBA-Fe-900 with a high specific surface area of 1567 m g exhibits an activity similar to that of Pt/C catalyst, a higher tolerance to methanol than Pt/C, and long-term durability. This work supplies a simple and convenient route for the preparation of metal-containing carbon electrocatalysts.

Section: Resultssupporting

confidence: 56%

Metal‐Nitrogen‐doped Porous Carbons Derived from Metal‐Containing Ionic Liquids for Oxygen Reduction Reaction

Wang

Chemistry An Asian Journal

et al. 2018

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“…The weak CO peak may be attributed to the presence of C(O)OH, originating from the precursors or O‐containing species on the surface of fibrous carbon. The high‐resolution N 1s spectroscopy displayed three prominent peaks, corresponding to pyridinic‐N (398.0 eV), pyrrolic‐N (400.1 eV), and graphitic‐N (401.0 eV) . Incorporating N‐species (particularly pyridinic‐N and graphitic‐N) into the carbon matrix has a positive impact on enhancing the overall electrical conductivity and wettability, thus accelerating the transfer of electron and charge .…”

Section: Resultsmentioning

confidence: 99%

Electrospun N‐Doped Porous Carbon Nanofibers Incorporated with NiO Nanoparticles as Free‐Standing Film Electrodes for High‐Performance Supercapacitors and CO₂ Capture

et al. 2018

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Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition-metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle-dispersed electrospun N-doped porous CNF (NiO/PCNF) and as free-standing film electrode for high-performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N-doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free-standing NiO/PCNF electrodes show a high specific capacitance of 850 F g at a current density of 1 A g in 6 m KOH aqueous solution, good rate capability, as well as excellent long-term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO uptake, and high-efficiency CO electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high-performance supercapacitors and CO electroreduction.

“…The key to success of HCSs in various applications is based on the availability of precisely controlled diameter and shell thickness, surface chemistry, and dispersibility in media. Numerous investigations have been devoted to the synthesis of porous carbon spheres via various strategies, including hard or soft‐templating method, emulsion self‐assembly process, and stöber‐based routes . Among the studies reported, many have focused on the preparation of hollow structural units with tunable sizes.…”

Section: Introductionmentioning

confidence: 99%

Space‐Confined Synthesis of ZIF‐67 Nanoparticles in Hollow Carbon Nanospheres for CO₂ Adsorption

Zhu

et al. 2019

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The synthesis of HCSs based core-shell structured nanocomposite can offer many benefits and potential applications. First, the remarkable durability stemming from the carbon framework would be highly beneficial for enduring harsh reaction conditions including acidic, alkaline, and organic regent. [4] Secondly, meso-/ micropores distributed on the surface of carbon shell can provide pathways for the diffusion of mass, which would reduce the diffusion resistance. [6] Last but not the least, the presence of huge inner space of HCSs with respect to the volume of carbon shell itself affords a huge reaction site. Therefore, it is important to experimentally and theoretically investigate the inner space of HCSs-based nanocomposites with controllable sizes for their optimum utilization.Zeolitic imidazole frameworks (ZIFs) with tetrahedral network topologies are a subclass of metal-organic frameworks (MOFs) composed of transition metals (Co, Cu, Zn, etc.) linked by imidazole ligands, which have attracted extensive interest since the original report by Yaghi and co-workers. [16,17] High porosity originating from high crystallinity and regular topology structure makes ZIFs one of the best porous materials for the selective capture of CO 2 . [18][19][20][21][22][23][24][25][26][27] The outstanding chemical and thermal stability of ZIFs are also favorable for its application under harsh conditions. [28][29][30][31][32][33][34][35] It is well established that the surface-to-volume ratio and total porosity of ZIFs are inversely related to its size, and have a significant influence on the adsorption capacity. [36,37] In this regard, reducing ZIFs to nanoscale size is favorable for increasing specific surface area and total porosity as well as enhancing uptake and selectivity.In this context, we report the synthesis of ZIF-67@HCSs material via a space-confined strategy, and its application for CO 2 capture. The as-synthesized ZIF-67@HCSs exhibited a unique core-shell structure composed of single microporous carbon shell and several nanoscale ZIF-67 cores. Due to the nanoconfined environment inside HCSs, these nanoreactors outperformed the conventional solution-based synthesis. [38] The results showed that:(1) the huge inner space of HCSs could be fully utilized without volume expansion, thus enhancing the tap density; (2) spaceconfined synthesis could control the size and morphology of ZIF-67 nanoparticles; (3) high chemical and thermal stability of ZIF-67 nanoparticles protected by hydrophobic carbon shell can avoid the moisture effects for real postcombustion gas separation, and therefore enhance the long-term stability. As expected, the ZIF-67@HCSs endowed with controlled morphology and high porosity exhibited outstanding adsorption capacity for CO 2 .Herein, the design and synthesis of ZIF-67 nanoparticles (NPs) with tunable size grown inside hollow carbon nanospheres (ZIF-67@HCSs) via a space-confined strategy is reported. HCSs are first prepared via pyrolysis of polystyrene@polypyrrole (PS@PPy) composite nanospheres. Furthe...