Abstract:

In this study, the graphite powder/Nafion-Pb electrode was prepared by using Nafion solution as binder and coated with graphite powder on Pb electrode. The prepared electrode was characterized by BET and SEM and used in electrolysis experiment. It was observed that the specific surface area of the graphite powder/Nafion-Pb electrode was 0.3022m²/g, which was much larger than that of the bare Pb-electrode, and the graphite powder supported on the surface of Pb formed flake patches, which could provide more active sites for electroreduction of oxalic acid. The oxalic acid reduction activity and glycolic acid selectivity were evaluated through a series of electrolysis experiments at a range of potential and temperature. The results showed that the conversion rate of oxalic acid reached 50.85%, glycolic acid selectivity reached 73.26% and Faraday efficiency reached 80.85% of the graphite powder/Nafion-Pb electrode were significantly higher than those of the Pb electrode when the saturated calomel electrode was used as reference electrode at a constant reduction potential of -1.6V and a temperature of 60℃.

Key words: electrochemistry, electroreduction of oxalic acid, glycollic acid, surface, graphite powder coating

摘要：

以Nafion溶液为黏结剂，在纯铅基体上涂覆4.17μm的石墨粉颗粒，制备了石墨粉/Nafion-铅复合电极，对其进行了比表面积分析及扫描电子显微镜镜表征，并用于电还原草酸制备乙醇酸的实验。可以观察到石墨粉/Nafion-铅复合电极的比表面积为0.3022m²/g，远大于纯铅比表面积，并且负载在铅表面的石墨粉形成斑块和裂缝结构，能够为草酸电还原提供更多的活性位点，使草酸能够在电极表面进行四电子的深度还原，从而生成更多的乙醇酸。通过改变电位、温度等工艺条件进行了一系列电还原实验，评价了其草酸还原活性及乙醇酸选择性等性能，结果表明以饱和甘汞电极为参比电极，在恒定还原电位-1.6V、60℃的条件下，石墨粉/Nafion-铅复合电极对草酸的转化率达到了50.85%，乙醇酸的选择性高达73.26%，且乙醇酸的法拉第效率为80.90%，这些性能均显著优于纯铅电极。

关键词: 电化学, 草酸电还原, 乙醇酸, 表面, 石墨粉涂层