Wang Ying, Qu Jiuhui, Wu Rongcheng, Lei Pengju
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.
Water Res. 2006 Mar;40(6):1224-32. doi: 10.1016/j.watres.2006.01.017. Epub 2006 Feb 28.
The Pd/Sn-modified activated carbon fiber (ACF) electrodes were successfully prepared by the impregnation of Pd2+ and Sn2+ ions onto ACF, and their electrocatalytic reduction capacity for nitrate ions in water was evaluated in a batch experiment. The electrode was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS) and temperature programmed reduction (TPR). The capacity for nitrate reduction depending on Sn content on the electrode and the pH of electrolyte was discussed at length. The results showed that at an applied current density of 1.11 mA cm(-2), nitrate ions in water (solution volume: 400 mL) were reduced from 110 to 3.4 mg L(-1) after 240 min with consecutive change of intermediate nitrite. Ammonium ions and nitrogen were formed as the main final products. The amount of other possible gaseous products (including NO and N2O) was trace. With the increase of Sn content on the Pd/Sn-modified ACF electrode, the activity for nitrate reduction went up to reach a maximum (at Pd/Sn = 4) and then decreased, while the selectivity to N2 was depressed. Higher pH value of electrolyte exhibited more suppression effect on the reduction of nitrite than that of nitrate. However, no significant influence on the final ammonia formation was observed. Additionally, Cu ion in water was found to cover the active sites of the electrode to make the electrode deactivated.
通过将Pd2+和Sn2+离子浸渍到活性炭纤维（ACF）上，成功制备了Pd/Sn修饰的活性炭纤维电极，并在批量实验中评估了它们对水中硝酸根离子的电催化还原能力。通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）、X射线光电子能谱（XPS）和程序升温还原（TPR）对电极进行了表征。详细讨论了电极上Sn含量和电解液pH值对硝酸盐还原能力的影响。结果表明，在施加电流密度为1.11 mA cm(-2)时，经过240分钟，水中（溶液体积：400 mL）的硝酸根离子从110 mg L(-1)降至3.4 mg L(-1)，中间产物亚硝酸盐不断变化。铵离子和氮气是主要的最终产物。其他可能的气态产物（包括NO和N2O）的量很少。随着Pd/Sn修饰的ACF电极上Sn含量的增加，硝酸盐还原活性先升高至最大值（Pd/Sn = 4时），然后降低，而对N2的选择性降低。电解液较高的pH值对亚硝酸盐还原的抑制作用比对硝酸盐还原的抑制作用更大。然而，未观察到对最终氨生成有显著影响。此外，发现水中的Cu离子会覆盖电极的活性位点，使电极失活。
