Browsing by Author "Masa, Justus"

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Co-Mn hybrid oxides supported on N-doped graphene as efficient electrocatalysts for reversible Oxygen electrodes
(Journal of The Electrochemical Society., 2018-06-27) Lu, Zhenjie; Chen, Xingxing; Liu, Penggao; Huang, Xinning; Wei, Jiong; Ren, Zhong; Yao, Songdong; Fang, Zhigang; Wang, Tao; Masa, Justus
Journal of The Electrochemical Society The Electrochemical Society, find out more Co-Mn Hybrid Oxides Supported on N-Doped Graphene as Efficient Electrocatalysts for Reversible Oxygen Electrodes Zhenjie Lu1, Xingxing Chen7,1, Penggao Liu2, Xinning Huang3, Jiong Wei6,1, Zhong Ren1, Songdong Yao1, Zhigang Fang1, Tao Wang7,2 and Justus Masa7,4,5 Published 27 June 2018 • © 2018 The Electrochemical Society Journal of The Electrochemical Society, Volume 165, Number 9 Citation Zhenjie Lu et al 2018 J. Electrochem. Soc. 165 H580 141 Total downloads 99 total citations on Dimensions. Turn on MathJax Get permission to re-use this article Share this article Share this content via email Share on Facebook (opens new window) Share on Twitter (opens new window) Share on Mendeley (opens new window) Hide article information Author affiliations 1 Research Group of Functional Materials for New Energy, School of Chemical Engineering, University of Science and Technology Liaoning, 114051 Anshan, People's Republic of China 2 Key Laboratory of Energy Materials Chemistry, Institute of Applied Chemistry, Xinjiang University, 830046 Urumqi, People's Republic of China 3 Engineering Training Center, University of Science and Technology Liaoning, 114051 Anshan, People's Republic of China 4 Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum, 44780 Bochum, Germany 5 Department of Chemistry, Kyambogo University, Kyambogo, Uganda Author notes 6 Present address: College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, Nankai University, 300071 Tianjin, China. 7 E-mail: xingchenstar79@163.com; renbility@163.com; justus.masa@rub.de ORCID iDs Xingxing Chen https://orcid.org/0000-0002-5754-2236 Justus Masa https://orcid.org/0000-0002-8555-5157 Dates Received 5 January 2018 Published 27 June 2018 DOI https://doi.org/10.1149/2.1411809jes Buy this article in print Journal RSS Sign up for new issue notifications Create citation alert Abstract Despite metal-air batteries possessing very high theoretical energy densities, inefficient reversibility of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) at the oxygen electrode undermines their rechargeability, which has slowed their market entry. Herein, we demonstrate a simple procedure for synthesis of a hybrid of MnO and metallic Co supported on N-doped graphene that exhibits activity and stability as a bifunctional ORR/OER catalyst, with a round trip ORR/OER overvoltage of 0.85 V, which remained constant for at least 70 h when cycling alternately, between oxygen evolution at a current density of 10 mA cm−2 and oxygen reduction at −1 mA cm−2. Insights into the key properties of the catalyst that influence its performance are proposed based on structural characterization by TEM, SEM, Raman spectroscopy, XRD and XPS. Besides MnO and metallic Co as the predominant crystalline species in the Co-Mn hybrid oxide, XPS revealed Mn3O4 and CoO rich surfaces, ascribed to oxidation of MnO and metallic Co due to atmospheric exposure. The synergetic interaction between the Co-Mn hybrid oxides and N-doped graphene, as well as Co-Mn interaction, favor improved ORR, OER and bifunctional ORR/OER performance of the catalyst.
Fatty acid composition of muscle, liver, and adipose tissue of freshwater fish from Lake Victoria, Uganda
(Journal of Aquatic Food Product Technology., 2011) Masa, Justus; Ogwok, Patrick; Muyonga, John Herbert; Kwetegyeka, Justus; Makokha, Vincent; Ocen, Denis
Fish oils may differ in fatty acid (FA) composition depending on diet. Oils extracted from muscle, liver, and adipose tissue of Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus), silver fish (Rastrineobola argentea), lungfish (Protopterus aethiopicus), Victoria squeaker (Synodontis victoriae), and two catfishes (Clarias gariepinus and Bagrus docmac) from Lake Victoria, a tropical freshwater lake, were evaluated for FA composition. Oil contents of muscles, livers, and adipose tissues were in the range of 3.16 to 13.8%, 3.62 to 53.4%, and 28.8 to 42.4%, respectively. Omega-3 polyunsaturated FA, particularly alpha-linolenic (ALA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids, were found to be in substantial amounts in oils from all seven fish species. Ratios of polyunsaturated FA to saturated FA (0.79 to 1.18) were in the range considered adequate for normal health. Overall, the results show that the fish species studied are a rich source of omega-3 polyunsaturated FA.
Lignosulfonate biomass derived N and S co-doped porous carbon for efficient oxygen reduction reaction
(Royal Society of Chemistry., 2018-06-26) Zhang, Mingli; Song, Yanliang; Tao, Hengcong; Yan, Chao; Masa, Justus; Liu, Yongchao; Shi, Xiaoyou; Liu, Shizhen; Zhang, Xu; Sun, Zhenyu
Finding sustainable, active, inexpensive, and stable electrocatalysts to replace Pt-based materials for the oxygen reduction reaction (ORR) remains a significant challenge. Here we report the use of functionalized lignin biomass as both carbon and dopant source for the direct synthesis of N and S dual-doped carbon sheet networks with abundant mesopores and high surface area. The resulting N and S-doped porous carbon exhibits good activity, long-term durability, and high selectivity for metal-free oxygen reduction electrocatalysis, approaching the performance of 20 wt% Pt/C, the state of the art ORR catalyst. Our method using natural biological resources thus offers a promising way to produce very promising noble metal-free ORR catalysts with potential application in alkaline fuel cells and metal–air batteries.