Preparation of hybrid films containing gold nanoparticles and cobalt porphyrin with flexible electrochemical properties

We report on the fabrication of hybrid films of gold nanoparticles (AuNPs) and [tetrakis (N-methylpyridyl)porphyrinato] cobalt (CoTMPyP) based on electrostatic layer-by-layer (LBL) self-assembly technique. A three-dimensional nanostructured film composed of positively charged CoTMPyP and negatively charged poly(acrylic acid)-stabilized AuNPs can be formed onto various substrates, including 4-aminobenzoic acid modified glassy carbon electrode, 11-mercaptotroponic acid modified gold film, and quartz plate with negatively charged surface. The regular growth of hybrid films is investigated by UV-vis spectroscopy, surface plasma resonance, and impedance spectroscopy. The prepared multilayer films possess flexible electro-catalytic activity toward O2 reduction reaction. It is noted that the electro-catalytic capability of the prepared multilayer film decreases as bilayer number increases. The unexpected observation of catalytic activity with bilayer number is investigated in detail.