Abstract:

Electrochemical reduction of CO₂ by renewable electricity is regarded as a promising method to storage energy and reduce emissions environmental problems. However, the hydrogen evolution side reaction at the cathode will reduce the performance of electrochemical reduction of CO₂. Nanowires were prepared on the copper foam electrode to expand the electrochemical active area of the electrode. Then, the copper foam nanowire electrode was treated with trimethoxy (1H, 1H, 2H, 2H-heptadecafluorodecyl) silane to make the electrode surface change from aerophobic to aerophilic, which was expected to strengthen the mass transfer of gas-phase CO₂, increase the three-phase contact line of the reaction and further improve the performance of electrochemical reduction of CO₂. Experimental results showed that compared with the copper foam nanowire electrode without aerophilic treatment, although the prepared aerophilic electrode possessed lower electrochemical active area, its superaerophilic property was conducive to the mass transfer of CO₂, inhibited the transport of H⁺ in electrolyte and weakened the hydrogen evolution side reaction. As a result, the H₂ Faraday efficiency dropped by 17.7% at -1.5V (vs. Ag/AgCl) and the performance of electrochemical reduction of CO₂ was improved.

Key words: electrochemical, reduction, carbon dioxide, copper nanowires, superaerophilic, mass transfer

摘要：

利用可再生电能进行电化学还原CO₂被认为是一种有前景的储能和减排技术，但在阴极发生析氢副反应，将降低电化学还原CO₂的性能。采用泡沫铜为基底制备铜纳米线电极扩展电极的电化学活性面积，然后通过十七氟癸基三甲基硅烷对电极进行亲气处理，使电极表面从疏气状态变为超亲气状态，从而强化气相反应物CO₂传质，增加反应三相接触线，提高电极的电化学还原 CO₂性能。实验结果表明：与未亲气处理的泡沫铜纳米线电极相比，所制备的超亲气泡沫铜纳米线电极虽然具有较小的电化学活性面积，但其超亲气的特性更有利于CO₂的传质，抑制了电解液中氢离子的传输，有效削弱了析氢副反应的发生。在电解电位为-1.5V（vs. Ag/AgCl）时，H₂法拉第效率降低了17.7%，电化学还原CO₂性能提升。

关键词: 电化学, 还原, 二氧化碳, 铜纳米线, 超亲气, 传质