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Insights into perovskite-catalyzed peroxymonosulfate activation: Maneuverable cobalt sites for promoted evolution of sulfate radicals
Applied Catalysis B: Environment and Energy ( IF 22.1 ) Pub Date : 2017-09-01 , DOI: 10.1016/j.apcatb.2017.08.088
Xiaoguang Duan , Chao Su , Jie Miao , Yijun Zhong , Zongping Shao , Shaobin Wang , Hongqi Sun

Metal-based catalysis has significantly contributed to the chemical community especially in environmental science. However, the knowledge of cobalt-based perovskite for aqueous phase oxidation still remains equivocal and insufficient. In this study, we discovered that Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite was exclusively effective for peroxymonosulfate (PMS) activation to produce free radicals, whereas the BSCF was inert to activate peroxydisulfate (PDS) and hydrogen peroxide. The BSCF/PMS exhibited superior performance to the benchmark Co3O4 nanocrystals and other classical PMS activators such as α-MnO2 and spinel CoFe2O4, meanwhile achieving an impressive stability with manipulated cobalt leaching in neutral and basic environment. In situ electron paramagnetic resonance (EPR) revealed the evolution of massive sulfate radicals (SO4) and hydroxyl radicals (OH) during the oxidation. A comprehensively comparative study of BSCF and Co3O4 nanocrystals was performed, including electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) in PMS solution as well as hydrogen temperature-programmed reduction (H2-TPR) and oxygen temperature-programmed desorption (O2-TPD) tests. The results unveil that the cobalt-based perovskite, BSCF, exhibited a better electrical conductivity and redox potential than the spinel cobalt oxide to interact with PMS. More importantly, the oxygen vacancies and less-electronegativity A-site metals may secure cobalt sites with a lower valence state for donating electrons to PMS simultaneously for radical generation. This study advances the mechanism of cobalt-based heterogeneous catalysis in environmental remediation.



中文翻译:

钙钛矿催化过氧单硫酸盐活化的见解:可操纵的钴位点,促进硫酸根自由基的进化

金属基催化为化学界做出了重要贡献,尤其是在环境科学领域。但是,钴基钙钛矿用于水相氧化的知识仍然是模棱两可和不足的。在这项研究中,我们发现Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O3 (BSCF)钙钛矿仅对过氧一硫酸盐(PMS)活化产生自由基有效,而BSCF对活化过氧二硫酸盐(PDS)和氢是惰性的过氧化物。所述BSCF / PMS表现出优异的性能,以基准钴3 ö 4个纳米晶体和其他经典PMS活化剂如α-MnO的2和尖晶石的CoFe2 O 4,同时在中性和碱性环境中通过操纵钴的浸出实现了令人印象深刻的稳定性。原位电子顺磁共振(EPR)揭示硫酸盐块状原子团(SO的演变4 - )和羟基自由基(OH)在氧化过程中。对BSCF和Co 3 O 4纳米晶体进行了全面的比较研究,包括PMS溶液中的电化学阻抗谱(EIS)和循环伏安图(CV)以及氢气程序升温还原(H 2 -TPR)和氧气程序升温解吸(O 2-TPD)测试。结果表明,钴基钙钛矿BSCF的电导率和氧化还原电势高于尖晶石型钴氧化物与PMS的相互作用。更重要的是,氧空位和负电性较低的A位金属可确保以较低价态形成钴位,以便同时向PMS供电子以产生自由基。这项研究提出了环境修复中钴基多相催化的机理。

更新日期:2017-09-01
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