Investigation on mechanism of catalysis by Pt-LiCoO2 for hydrolysis of sodium borohydride using X-ray absorption.

The synthesis of platinum nanoparticle loaded LiCoO2 (Pt-LiCoO2) was carried out successfully by an impregnation method followed by sintering at different temperatures. The catalytic role of Pt-LiCoO2 composite in hydrogen generation during hydrolysis of sodium borohydride (NaBH4) was studied for fuel cell applications. X-ray diffraction (XRD), transmission electron microscopy (TEM), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) have been used to elucidate the structural and catalytic properties of Pt-LiCoO2. It was found that the 15 wt % of Pt nanoparticles on LiCoO2 sintered at 450 degrees C support showed the maximum efficiency for the catalysis reaction of hydrogen production. X-ray absorption near edge structure (XANES) analysis and extended X-ray absorption fine structure (EXAFS) analysis using a synchrotron radiation source were performed to carry out ex situ measurements in order to understand the mechanism of the catalytic process for the production of hydrogen during the hydrolysis of NaBH4. Co K-edge XANES showed a small percentage of cobalt in the metallic form after hydrogen generation which suggests the reduction of the cobalt during the hydrolysis of NaBH4.