Fabrication and electrocatalytic activities of porphyrin and 12-molybdophosphoric acid hybrid films.

Hybrid films composed of oppositely charged Keggin-type 12-molybdophosphoric acid H(3)PMo(12)O(40).nH(2)O (PMo(12)) and water-soluble cationic meso-tetra (N-methyl-4-pyridyl) porphinetetratosylate (TMPyP) were fabricated onto silicon and ITO substrates by a layer-by-layer (LbL) self-assembly technique. The LbL films were characterized by UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and cyclic voltammetry (CV). The electrochemical properties of the prepared multilayer films were controlled by adjusting the solution pH. Moreover, with increase in the layer number of TMPyP/PMo(12), the electrocatalytic current toward the reduction of IO(3)(-) was enhanced. The LbL films also displayed good electrocatalytic activities toward the reduction of BrO(3)(-), IO(3)(-) , and S(2)O(8)(2-).