NH_4~+对甲酸在炭载Pd催化剂上氧化性能的影响

为了解HClO4、NH4ClO4和NaClO4电解液对炭载Pd(Pd/C)催化剂电极对甲酸氧化的电催化性能的影响,在用X射线衍射(XRD)谱、能量色散谱(EDS)和透射电子显微镜(TEM)对Pd/C催化剂进行表征的基础上,采用电化学方法测量了Pd/C催化剂在不同电解液中对甲酸氧化的电催化性能.发现在不同电解液中,Pd/C催化剂对甲酸氧化的电催化活性和稳定性按NH4ClO4NaClO4HClO4的次序降低.由于甲酸的存在,不同电解液的pH相差较小,因此,电解液的pH影响较小,而阳离子的影响较大.在NaClO4电解液中的性能优于在HClO4电解液中的性能是pH的影响.在NH4ClO4电解液中的性能优于在NaClO4电解液中是由于NH4+能降低CO在Pd/C催化剂电极上的吸附强度和吸附量,这一发现对提高直接甲酸燃料电池(DFAFC)的性能很有意义.

Effect of NH4+ on the Electrocatalytic Performance of Carbon Supported Pd Catalyst for Formic Acid Oxidation

We investigated the effect of HClO₄, NH₄ClO₄, and NaClO₄ electrolytes on the electrocatalytic performance of a Pd/C catalyst electrode for formic acid oxidation. The Pd/C catalyst was characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The performance of the Pd/C catalyst electrode during formic acid oxidation in different electrolytes was measured using electrochemical methods. We found that the electrocatalytic activity and stability of the Pd/C catalyst electrode for formic acid oxidation decreased in the following order: NH₄ClO₄ > NaClO₄ > HClO₄. The difference in pH between the different electrolytes was small because of the presence of formic acid. Therefore, the electrolyte pH has a small effect and the cations have a large effect. The better performance of the NaClO₄ electrolyte compared to the HClO₄ electrolyte is due to a pH effect. The better performance of the NH₄ClO₄ electrolyte compared to the NaClO₄ electrolyte is due to NH₄⁺ decreasing the adsorption strength and amount of CO on the Pd/C catalyst. This finding has large significance for the increase in the performance of the direct formic acid fuel cell (DFAFC).