Synthesis and characterization of sub-10 nm Platinum Hollow Spheres as electrocatalyst of direct methanol fuel cell

Platinum Hollow Spheres (PHSs) with diameters less than 10 nm were successfully synthesized by using Co as a sacrificial template and H2PtCl6 as an oxidizing agent at 95 degrees C. The formation of PHSs at this temperature was not affected by citrate reduction and mainly depended on the pH. The results of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray, diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the platinum hollow sphere was mainly constructed by fcc (face cubic center) platinum with tiny crystallites on the shell. The performance of PHSs for methanol electro-oxidation was evaluated and compared with commercial E-TEK platinum black. Electrochemical measurement by cyclic voltammetry (CV) demonstrated that the electrochemical surface area of PHSs was about twice higher than E-TEK platinum black. Therefore, the synthesized PHSs had higher electrocatalytic activity for methanol electro-oxidation.