Fabrication of silver nanoparticles in titanium dioxide/poly(vinyl alcohol) alternate thin films: a nonenzymatic hydrogen peroxide sensor application

Abstract

Silver nanoparticles (AgNPs) were readily synthesized in TiO2/poly(vinyl alcohol) (PVA) ultrathin films, which is alternately assembled with Ti(O-nBu)4 and PVA via a surface sol-gel process. The photochemical reduction of as-embedded Ag+ ions in the film led to the formation of well-controllable AgNPs in size, distribution and electrochemical properties. AgNP-immobilized TiO2/PVA films were characterized by quartz crystal microbalance measurements, ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical measurements. The increase in thickness of TiO2/PVA hybrid films led to an increase in the surface plasmon resonance peak, showing a blueshift in UV-vis absorption. As the alternate cycles of TiO2/PVA thin film increased (3.5-, 5.5-, and 10.5-cycle), the sizes of prepared AgNPs gradually decreased (9.3, 8.0, and 6.2 nm, respectively) and the distributions of the AgNPs become narrower, correspondingly. Regarding its electrochemical properties, the TiO2/PVA hybrid films showed a well-defined reversible redox system on gold electrodes (GEs), as observed by a pair of current peaks, and further exhibited electrocatalytic activity, and a low limit of detection (LOD) for hydrogen dioxide (H2O2). A lower cycle of thinner hybrid film, 1.5-cycle TiO2/PVA, showed relatively higher electrochemical and amperometric responses than those of 3.5-, 5.5-, and 10.5-cycle films. Based on the amperometric response of the AgNP-incorporated 1.5-cycle TiO2/PVA film, the linear regression equation was acquired as I(μA) = -0.0481 [H2O2] (μM) + 0.4099, with a correlation coefficient of 0.9872. Thus, the significant sensitivity to H2O2 up to 0.0481 μA/μM and LOD of 0.11 μM were achieved, respectively.