Study of Direct Synthesis of Hydrogen Peroxide Acid Solutions at a Heat-Treated MnCl鈥揚orphyrin/Activated Carbon Cathode from H2 and O2

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• 作者：Ichiro Yamanaka ; Takeshi Onizawa ; Hirobumi Suzuki ; Noriko Hanaizumi ; Naoya Nishimura ; Sakae Takenaka
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：February 23, 2012
• 年：2012
• 卷：116
• 期：7
• 页码：4572-4583
• 全文大小：596K
• 年卷期：v.116,no.7(February 23, 2012)
• ISSN：1932-7455

文摘

Heat-treated MnCl鈥損orphyrin supported on activated carbon (AC) catalyzed electrochemical reduction of O₂ to H₂O₂ using an H₂/O₂ fuel cell reactor. Suitable preparation conditions for an Mn鈥損orphyrin electrocatalyst were studied for the H₂O₂ formation, such as types of porphyrin rings, heat-treatment temperatures in He, and Mn loadings. The effects of reaction conditions, H₂SO₄ concentration, P(O₂), P(H₂), and electrolyte flow on the H₂O₂ formation were studied. Then, 0.5 wt % MnCl鈥揟PP/AC heat treated at 823 K and 0.3 wt % MnCl鈥揙EP/AC heat treated at 723 K showed good electrocatalytic activities for the H₂O₂ formation (TPP: 5,10,15,20-tetrakis(phenyl)-21H,23H-porphyrin, OEP: 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin). A maximum H₂O₂ concentration of 1.0 mol dm^鈥? with 47% current efficiency (CE) was obtained under suitable conditions. The heat-treated MnCl鈥揟PP/AC and MnCl鈥揙EP/AC electrocatalysts were characterized using temperature-programmed desorption, X-ray absorption near-edge structure spectroscopy, elemental analysis, cyclic voltammetry, and rotating ring-disk electrode voltammetry. Elimination of Cl from MnCl鈥揟PP and MnCl鈥揙EP supported on AC was essential to generate an active site for the H₂O₂ formation. A model of the Mn active site was proposed.