AUTHOR=Khan Karim , Tareen Ayesha Khan , Aslam Muhammad , Zhang Yupeng , Wang Renheng , Khan Sayed Ali , Khan Qudrat Ullah , Rauf Muhammad , Zhang Han , Ouyang Zhengbiao , Guo Zhongyi TITLE=Facile Synthesis of Mayenite Electride Nanoparticles Encapsulated in Graphitic Shells Like Carbon Nano Onions: Non-noble-metal Electrocatalysts for Oxygen Reduction Reaction (ORR) JOURNAL=Frontiers in Chemistry VOLUME=7 YEAR=2020 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00934 DOI=10.3389/fchem.2019.00934 ISSN=2296-2646 ABSTRACT=

This manuscript presented a large scale synthesis of Graphitic Shells like carbon nano onions (GS-CNOs) by direct solution method using mayenite electride as a catalyst for synthesis of CNOs. Thermal characterization, microstructural analysis, and high resolution electron microscopy have confirmed the graphitization and revealed the resulting GS-CNOs with particle size about 15 nm, maximum BET surface area of 214 m2.g−1, and moderate conductivity of 250 S.cm−1, thus providing a new approach to synthesize GS-CNOs. The reported GS-CNOs, which acts as more active but less expensive electrocatalysts with onset potential of 1.03 V, half wave potential of 0.88 V vs. the reversible hydrogen electrode (RHE), and limited current density of 5.9 mA.cm−2, higher than that of benchmark 20% Pt/C (1.02 eV, 0.82 V, 5.2 mA.cm−2). The synthesized nano-powder acts as an origin of ORR activity via a four electron (4e−) pathway, along with significantly enhanced stability, in alkaline media. The high ORR activity is ascribed to GS-CNOs embedded sufficient metallic C12A7:e− particles, which favor faster electron movement and better adsorption of oxygen molecules on catalyst surface. Hence, we explored first time large scale synthesis of GS-CNOs with gram level and provide efficient approach to prepare novel, lowest cost, potential non-noble metals catalyst for fuel cells.