Fabrication of a Metalloporphyrin−Polyoxometalate Hybrid Film by a Layer-by-Layer Method and Its Catalysis for Hydrogen Evolution and Dioxygen Reduction

Abstract

[Tetrakis ( N -methylpyridyl) porphyrinato] cobalt (CoTMPyP) and 1:12 silicotungstic acid (SiW 12 ) were alternately deposited on a 4-aminobenzoic acid (4-ABA) -modified glassy carbon electrode through a layer-by-layer method. The resulting organic−inorganic hybrid films were characterized by cyclic voltammetry (CV) and UV/vis absorption spectroscopy. We proved that the prepared multilayer films are uniform and stable. SiW 12 -containing multilayer films (SiW 12 as the outermost layer) exhibit remarkable electrocatalytic activity for the hydrogen evolution reaction (HER). The kinetic constants for HER were comparatively investigated at different layers of SiW 12 /CoTMPyP multilayer film-modified electrodes by hydrogen evolution voltammetry. In addition, rotating disk electrode (RDE) and rotating ring−disk electrode (RRDE) voltammetric methods confirm that SiW 12 /CoTMPyP (CoTMPyP as the outermost layer) multilayer films catalyze almost a two-electron reduction of O 2 to H 2 O 2 in pH 1−6 buffer solutions. Furthermore, P 2 W 18 /CoTMPyP films were also assembled, and their catalytic activity for HER is very different from that of SiW 12 /CoTMPyP multilayer films.