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Thermodynamically Stable Mesoporous C 3 N 7 and C 3 N 6 with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction
Author(s) -
Kim In Young,
Kim Sungho,
Premkumar Selvarajan,
Yang JaeHun,
Umapathy Siva,
Vinu Ajayan
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201903572
Subject(s) - mesoporous material , materials science , nitride , electron transfer , crystallography , chemistry , catalysis , nanotechnology , organic chemistry , layer (electronics)
Carbon nitrides with a high N/C atomic ratio (>2) are expected to offer superior basicity and unique electronic properties. However, the synthesis of these nanostructures is highly challenging since many parts of the CN frameworks in the carbon nitride should be replaced with thermodynamically less stable NN frameworks as the nitrogen content increases. Thermodynamically stable C 3 N 7 and C 3 N 6 with an ordered mesoporous structure are synthesized at 250 and 300 °C respectively via a pyrolysis process of 5‐amino‐1H‐tetrazole (5‐ATTZ). Polymerization of the precursor to the ordered mesoporous C 3 N 7 and C 3 N 6 is clearly proved by X‐ray and electron diffraction analyses. A combined analysis including diverse spectroscopy and FDMNES and density functional theory (DFT) calculations demonstrates that the NN bonds are stabilized in the form of tetrazine and/or triazole moieties in the C 3 N 7 and C 3 N 6 . The ordered mesoporous C 3 N 7 represents the better oxygen reduction reaction (ORR) performances (onset potential: 0.81 V vs reversible hydrogen electrode (RHE), electron transfer number: 3.9 at 0.5 V vs RHE) than graphitic carbon nitride (g‐C 3 N 4 ) and the ordered mesoporous C 3 N 6 . The study on the mechanism of ORR suggests that nitrogen atoms in the tetrazine moiety of the ordered mesoporous C 3 N 7 act as active sites for its improved ORR activity.