ABSTRACT

In order to reduce CO₂ to ethanol, the CuIn alloy-particle modified CuInS₂ (CuIn AP/CIS) composite thin-film electrodes have been suggested and their catalytic activity and selectivity have been examined. The CuIn AP/CIS composite thin films have been fabricated via by two-step electrodeposition route – electrodepositing the Cu₂O particles on the CuInS₂ thin films, followed by electrodeposition of metallic indium on the Cu₂O/CuInS₂ thin films. Compared to the Cu₂O/CuInS₂ composite thin-film electrode, the CuIn AP/CIS composite thin-film electrode exhibits high catalytic activity and selectivity for ethanol formation. At the CuIn AP/CIS composite thin-film electrode with electrodeposition of In for 30 s, ethanol concentration reaches 0.046 mM at 1.5 h. The results of the electrochemical impedance spectra show that the interface charge-transfer is the rate-determining step in the CO₂ reduction process, and the CuIn AP/CIS composite thin-film electrode with electrodeposition of In for 30 s exhibits the smallest resistant of the interface charge-transfer. The study on the adsorbed intermediates shows that the surface modification of CuIn AP increases *CO coverage and decreases *H coverage significantly, thus promoting coupling of *CO. Therefore, the selectivity for ethanol formation is improved.

摘要

为了将CO ₂还原为乙醇，已经提出了CuIn合金颗粒改性的CuInS ₂ (CuIn AP/CIS)复合薄膜电极，并且已经检验了它们的催化活性和选择性。CuIn AP/CIS 复合薄膜是通过两步电沉积工艺制备的——在 CuInS ₂薄膜上电沉积 Cu ₂ O 颗粒，然后在 Cu ₂ O/CuInS ₂薄膜上电沉积金属铟。与 Cu ₂ O/CuInS _{2 相比}作为复合薄膜电极，CuIn AP/CIS 复合薄膜电极对乙醇形成具有高催化活性和选择性。在电沉积 In 30 s 的 CuIn AP/CIS 复合薄膜电极上，乙醇浓度在 1.5 h 时达到 0.046 mM。电化学阻抗谱结果表明界面电荷转移是CO _{2 中}的速率决定步骤。在还原过程中，电沉积 In 30 s 的 CuIn AP/CIS 复合薄膜电极表现出最小的界面电荷转移电阻。对吸附中间体的研究表明，CuIn AP的表面改性显着增加了*CO覆盖率并显着降低了*H覆盖率，从而促进了*CO的偶联。因此，提高了乙醇形成的选择性。