Investigation of the adsorption of phosphoric acid on platinum at elevated temperature by means of IR spectroscopy combined to electrochemical methods

该项目的目的是详细了解在高温下磷酸和其他磷酸盐在铂表面的吸附。这些光谱电化学研究应该提供有关吸附物质状态的信息。这意味着，例如，吸附的几何形状或在不同温度和电位下的质子化程度。这一信息对于理解高温聚合物电解质燃料电池阴极铂催化剂下的氧还原反应具有重要意义。磷酸在电化学活性表面上的吸附阻碍了该反应。拟建立一种利用表面敏感红外反射吸收光谱法研究吸附磷酸随外加电位和温度变化的方法。为此，一种电位调制技术，即减归一化界面傅立叶变换红外光谱（SNIFTIRS），将用于监测两个电位之间的差异。因此，在不存在磷酸吸附的情况下，电势用作参考，以显示吸附后的差异。利用这些数据可以更好地了解氧还原反应的阻碍随温度的变化。

The aim of this project is the detailed understanding of the adsorption of phosphoric acid and other phosphate species on platinum surfaces at elevated temperature. These spectroelectrochemical investigations should give information about the state of the adsorbed species. That means for example the adsorption geometry or the degree of protonation at various temperatures and potentials. This information is relevant for understanding the oxygen reduction reaction at platinum catalyst on the cathode of a high temperature polymer electrolyte fuel cell. This reaction is hindered by adsorption of phosphoric acid on electrochemically active surface sites.The establishment of a method, which uses the non-destructive surface sensitive infrared reflection absorption spectroscopy for investigation of the adsorbed phosphoric acid depending on the applied potential and temperature, is planned. For this purpose a potential modulation technique, the subtractively normalized interfacial fourier transform infrared spectroscopy (SNIFTIRS), will be used for monitoring the difference between two potentials. Thus, the potential, where no adsorption of phosphoric acid is present, is used as reference, to show the differences after adsorption. Using this data will lead to a better understanding of the hindrance of the oxygen reduction reaction depending on the temperature.