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    改性碳纸阳极偶联自然空气扩散阴极同步电合成过氧化氢

    Modified carbon paper anode coupled with a natural air-diffusion cathode for synchronous electrosynthesis of hydrogen peroxide

    • 摘要: 电化学合成过氧化氢(H2O2)是一种极具前景的H2O2合成方法,可通过阳极的二电子水氧化反应和阴极的二电子氧还原反应两种途径产生,现有研究仍以单极反应模式为主,存在电流效率偏低的问题。有鉴于此,设计并制备了聚偏二氟乙烯(PVDF)涂覆的碳纸阳极和无需曝气的自然空气扩散阴极(NADE),构筑了阴阳极偶联同步电化学合成H2O2体系。结果表明:(1)PVDF涂覆可提高碳纸的疏水性和亲气性,进而提升阳极电合成H2O2性能;(2)自然空气扩散阴极的工艺条件确定为以碳布为气体扩散层,聚四氟乙烯为粘结剂,负载量7.5 mg cm−2的氧化炭黑为催化剂;(3)在3 V vs. RHE电位下,质子交换膜分隔的电解槽中,阴阳极偶联体系可实现151.5%的总电流效率和36.9 μmol min−1的H2O2产率,其中阳极和阴极的电流效率分别为52.9% 和98.6%。此外,该体系可稳定运行超过12 h,H2O2生成量达到4.2 mmol。研究表明疏水亲气的碳纸阳极与自然空气扩散阴极的协同构筑可显著提高H2O2的总体电流效率,为其绿色高效电化学合成提供了新思路。

       

      Abstract: Electrochemical synthesis of hydrogen peroxide (H2O2) is a highly promising route for H2O2 production, which can proceed via two pathways: the two-electron water oxidation reaction at the anode and the two-electron oxygen reduction reaction at the cathode. However, current electrochemical H2O2 production is still dominated by single-electrode reaction modes, resulting in relatively low faradaic efficiency. To address this issue, we designed and fabricated a poly(vinylidene fluoride) (PVDF)-coated carbon fiber paper (CFP) anode and a natural air-diffusion cathode that operates without forced aeration, and further constructed an anode-cathode coupled electrochemical system for H2O2 synthesis. The results show that: (1) PVDF coating enhances the hydrophobicity and aerophilicity of CFP, thereby improving the anode performance for electrochemical H2O2 synthesis; (2) the optimized natural air-diffusion cathode employs carbon cloth as the gas diffusion layer, PVDF as the binder, and oxidized carbon black with a loading amount of 7.5 mg cm−2 as the catalyst; and (3) in a proton exchange membrane separated electrolytic cell, the coupled anode-cathode system achieved a total current efficiency of 151.5% and an H2O2 production rate of 36.9 μmol min−1 at 3 V vs. RHE, with anodic and cathodic faradaic efficiencies of 52.9% and 98.6%, respectively. In addition, the system operated stably for more than 12 h, during which the accumulated amount of H2O2 reached 4.2 mmol. These results demonstrate that the synergistic coupling of a hydrophobic and aerophilic CFP anode with a naturally air-diffusion cathode can significantly improve the overall faradaic efficiency for H2O2 production, providing a new strategy for its green and efficient electrochemical synthesis.

       

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