The catalytic activity of manganese oxynitrides in the oxygen reduction reaction (ORR) was investigated in alkaline solutions to clarify the effect of the incorporated nitrogen atoms on the ORR activity. These oxynitrides, with rock-salt-like structures with different nitrogen contents, were synthesized by reacting MnO, Mn2 O3 , or MnO2 with molten NaNH2 at 240-280 °C. The anion contents and the Mn valence states were determined by combustion analysis, powder X-ray diffraction, and X-ray absorption near-edge structure analysis. An increase in the nitrogen content of rock-salt-based manganese oxynitrides increases the valence of the manganese ions and reinforces the catalytic activity for the ORR in 1 m KOH solution. Nearly single-electron occupancy of the antibonding eg states and highly covalent Mn-N bonding thus enhance the ORR activity of nitrogen-rich manganese oxynitrides.
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December 2022
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
Luminescent materials are indispensable for applications in lighting, displays and photovoltaics, which can transfer, absorb, store and utilize light energy. Their performance is closely related with their size and morphologies, exact atomic arrangement, and local configuration about photofunctional centers. Advanced electron microscopy-based techniques have enabled the possibility to study nanostructures with atomic resolution.
View Article and Find Full Text PDFAnal Chim Acta
November 2021
Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, College of Chemistry and Chemical Engineering, Hubei University, Wuhan, 430062, China; State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, 430062, China. Electronic address:
In this work, boron carbon oxynitride quantum dots (BCNO QDs) were prepared by a one-step hydrothermal process of ethanolamine and boric acid. BCNO QDs exhibited blue fluorescence with the optimal excitation/emission fluorescence peak at 335 and 420 nm, respectively. As an efficient fluorescence quencher, manganese dioxide (MnO) nanosheets can effectively quench the fluorescence of BCNO QDs via the inner filter effect (IFE).
View Article and Find Full Text PDFEnviron Pollut
November 2021
Department of Chemistry, Research Institute of Physics and Chemistry, Jeonbuk National University, Jeonju, 54896, Republic of Korea. Electronic address:
In this work, we prepared nanocomposites of nickel-decorated manganese oxynitride on graphene nanosheets and demonstrated them as photocatalysts for degradation of acetylsalicylic acid (ASA). The catalyst exhibited a high degradation efficiency over ASA under visible light irradiation and an excellent structural stability after multiple uses. Compared to manganese oxide (MnO) and manganese oxynitride (MnON) nanoparticles, larger specific surface area and smaller band gap were observed for the nanocomposite accounting for the enhanced photocatalytic efficiency.
View Article and Find Full Text PDFACS Appl Mater Interfaces
December 2020
Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 50-1, Sang-Ri, Hyeonpung-Myeon, Dalseong-Gun, Daegu 42988, Republic of Korea.
Metal oxynitrides have been considered recently as emerging electrode materials for supercapacitors. Herein, we converted titanate nanotubes into a series of titanium oxynitride (TiON) nanorods at nitridation temperatures of 800, 900, and 1000 °C in ammonia gas and tested them as supercapacitor electrodes. TiON-800, TiON-900, and TiON-1000 showed capacities of 60, 140, and 71 F g, respectively, at a current density of 1 A g.
View Article and Find Full Text PDFChemSusChem
January 2017
Chemistry Department, Brookhaven National Laboratory, Upton, NY, 11973, United States.
We report the synthesis and characterization of graphenesupported cobalt-manganese-oxynitride nanocatalysts (CoMnON/G) as bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A nitriding treatment of spinel compound CoMnO increased the ORR activity considerably, and the most active material catalyzed the ORR with only a 30 mV half-wave potential difference from the commercial carbon-supported platinum (Pt/C) in alkaline media. In addition to high activity, the catalyst also exhibited an intrinsic stability that outperformed Pt/C.
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