In situ EXAFS investigation of carbon-supported Pt clusters under potential control

The transformation of carbon supported Pt clusters under potential control in 1M HClO4 solution was investigated by in-situ X-ray absorption spectrosc opy measurements. Both XANES and EXAFS data are used to show the structure evolution of the Pt clusters at various potentials. It showed that the whit e line area and the edge energy increase with the applied potential in the range 0.1 similar to 1.5V. The coordination number of oxygen and platinum o n the Pt/C electrode increases and decreases, respectively, with the applie d potential. It is found that the size of Pt cluster does not grow during t he electrode fabrication. However, the crystallization of Pt cluster occurs during the potential cycling.