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Ba0.5Sr0.5Co0.8Fe0.2O3-δ催化析氧催化剂氟离子取代/化学还原双活性位点构筑
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作者 张新磊 时佳维 蔡卫卫 《聊城大学学报(自然科学版)》 2020年第4期51-57,共7页
环境和能源问题是制约当今社会快速发展的两个瓶颈,而氢能作为一种清洁新型可再生能源技术具备同时解决这两个问题的潜力.电解水制氢被认为是闭环氢能链条的关键所在,而其中阳极析氧反应(OER)动力学缓慢是制约当前电解水技术大规模推广... 环境和能源问题是制约当今社会快速发展的两个瓶颈,而氢能作为一种清洁新型可再生能源技术具备同时解决这两个问题的潜力.电解水制氢被认为是闭环氢能链条的关键所在,而其中阳极析氧反应(OER)动力学缓慢是制约当前电解水技术大规模推广的主要问题.大量前期工作表明,以Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF)为代表的钙钛矿氧化物类催化剂具有优越的OER活性.为了进一步提升BSCF催化剂的OER活性,本论文使用氟离子取代和化学还原法在BSCF构筑活性氧O2-/O-和金属双活性位点,促进BSCF的OER活性的提升.结果表明,这种拥有双活性位点的改性BSCF催化剂表现出较原始BSCF催化剂高的多的OER催化活性。 展开更多
关键词 电化学析氧 钙钛矿氧化物 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 氟离子取代 化学还原
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Anionic polymerization of fluorine-substituted phenyl methacrylates
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作者 Bin Li Pan Zhou +2 位作者 Yuefei Chen Biao Jiang Hongping Zhu 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第1期107-113,共7页
Synthesis and anionic polymerization of the fluorine-substituted phenyl methacrylates are herein reported. A series of monodi-, and multi-substituted fluorophenyl methacrylates H2C=C(CH3)C(O)OC6H4F-4 (M^1a), H2... Synthesis and anionic polymerization of the fluorine-substituted phenyl methacrylates are herein reported. A series of monodi-, and multi-substituted fluorophenyl methacrylates H2C=C(CH3)C(O)OC6H4F-4 (M^1a), H2C=C(CH3)C(O)OC6H4F-3 (M^1b), HEC=C(CH3)C(O)OC6H3F2-2,4 (M^2), H2C=C(CH3)C(O)OC6H2F3-2,3,4 (M^3), H2C=C(CH3)C(O)OC6HF4-2,3,5,6 (M^4), and H2C=C(CH3)C(O)OC6F5 (M^5) were synthesized and characterized. Initially, the polymerization was carded out on the monomer M^1a by using nBuLi, tBuLi, and KH as the respective catalysts; this approach produced the polymers in yields of 12%-50%, but with lower molecular weights. Similar results were obtained by using tBuLi for catalytically polymerizing the other five monomers. By introducing a co-catalyst MeAl(BHT)2, the catalysts Nail, LiH, and tBuOLi each were tested to polymerize M^1a, which gave the polymers in very low yields (3%-7%). Polymer yields of 13%-27% were obtained by each of the catalysts LiAlH4, nBuLi, PhLi, and tBuLi in connection with MeAI(BHT)2, but a better yield (61%) was achieved with KH/MeAl(BHT)2. The KH/MeAl(BHT)2 catalyst system was further employed to polymerize M^1b and M^2, which afforded respective polymer yields of 12%-63% and 10%-53%, depending on the molar ratios of KH:MeAl(BHT)2 as well as on the monomer concentrations. All of the polymers produced were syndiotactically rich in structure, as indicated by either ^1H or ^19F NMR data. The polymerization mechanism by the combined catalyst system is proposed. 展开更多
关键词 fluorophenyl methacrylates the combined catalyst system anionic polymerization syndiotactic polymer ^1H and ^19F NMR data
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