A facile and template‐free synthetic approach was utilized to obtain a series of nitrogen and oxygen‐doped microporous carbon spheres (CTS‐X‐700) from carbazole‐terephthalaldehyde based co‐polymer spheres (CTS). The inherent spherical morphology of the co‐polymer remained intact even after activation at high temperature (700 °C). The synthesized materials exhibit BET surface area of up to 1340 m2 g−1 with an interconnected porous network consisting of ultramicropores and supermicropores along with a small amount of mesopores. Moreover, a good balance of heteroatom surface functionalities (N content up to 3.2 % and O content up to 12 %) was maintained without compromising the porosity by systematically varying the activation conditions. These features result in a high specific capacitance value of 407 F g−1 at 1.0 A g−1 in aqueous acid electrolyte with a three‐electrode system and superior cycle stability of 100 % capacitance retention even after 10000 cycles. Furthermore, the high energy density (10.6 W h kg−1 at a current density of 0.5 A g−1) in an aqueous electrolyte of the assembled supercapacitor device further demonstrates the possible applications of the synthesized materials as high‐performance energy storage devices.
Indole-based copolymer spheres serve as a precursor for the facile and easily scalable synthesis of a series of nitrogenrich microporous carbons. The influence of chemical activation and carbonization parameters on the morphology, chemical composition, and electrochemical behavior of the porous carbons has been monitored. The copolymers exhibit an inherent porous framework, which ensures abundant microporosity and BET surface area as high as 1255 m 2 g −1 in the porous carbon materials. Homogeneously distributed high nitrogen doping in the copolymer was maintained up to 3.8% even at a high carbonization temperature of 900 °C. The carbon material ITS-2-700 displays high specific capacitance in aqueous acidic (420 F g −1 ) and alkaline (357 F g −1 ) electrolytes. Moreover, the complete capacitance retention in both electrolytes emphasizes its feasibility as suitable supercapacitor materials. At a higher carbonization temperature of 900 °C, the porous carbon material (ITS-2-900) shows excellent ORR catalytic activity with a 0.99 V (vs RHE) onset potential and a high limiting current density (5.1 mA cm −2 ). ITS-2-900 exhibits superior durability and resistance toward methanol oxidation when compared with the commercial Pt/C electrocatalyst.
Exploring and designing a non‐precious metal‐based electrocatalyst for oxygen reduction reactions with high efficiency is imperative for commercializing fuel cell technology. In the present work, an approach to synthesize N, and S ‐doped porous carbon catalysts with trace Fe derived from N, S enriched hyper‐crosslinked polymer for ORR by ZnCl2 activation at high temperature is described. The optimized catalyst (HCP‐NSZn‐900) exhibited an impressive catalytic activity towards ORR due to its high surface area, excellent porosity, and effective doping of Fe and heteroatoms. Accordingly, HCP‐NSZn‐900 demonstrates a high onset potential of 0.98 V (vs. RHE) with a large diffusion‐limited current density of 4.72 mA cm−2, and improved tolerance to methanol crossover, significantly longer durability in contrast to the Pt/C catalyst. Furthermore, HCP‐NSZn‐900 confirmed the 4‐electron transfer selectivity (n∼4.0). Therefore, the synthesized materials could be a potential replacement for Pt/C catalyst for energy conversion technologies.
Developing an efficient metal‐free electrocatalyst to compete with the noble metal‐based catalysts for oxygen reduction reaction (ORR) is of great significance in the field of energy storage and conversion. We have designed a metal‐free electrocatalyst via dual doping of nitrogen and phosphorus in a porous carbon structure from a cyclotripolyphosphazene (CTP)‐based polymer. The optimized material (CTP‐800) demonstrates an excellent ORR catalytic performance with an onset potential of 0.89 V, a high limiting current density of 4.58 mA cm−2, and a favorable 4‐electrons mediated reaction mechanism in the KOH electrolyte. Moreover, the electrochemical stability, as well as methanol compatibility of CTP‐800, are superior to the commercially available Pt/C catalyst. The remarkable electrocatalytic performance of CTP‐800 can be credited to the high surface area with rich micropores/mesopores and homogenous distribution of heteroatoms.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.