Visible light driven photoelectrocatalytic salicylic acid oxidation on Bi2O3-TiO2/ITO thin films prepared by aqueous sol-gel

JOSE LUIS ROPERO VEGA; ROBERTO J. CANDAL; J.A. PEDRAZA-AVELLA,; M.E. NINO-GOMEZ; ALDABE BILMES, SARA

cartagena

Conferencia; 1st Conference on Semiconductor Photocatalysis, Solar Energy Conversion and Advanced Oxidation Technologies; 2013

Bismuth(III) oxide (Bi2O3) is a semiconductor with a band gap energy of 2.8 eV, which allow it to be excited with visible radiation [1]. However, it shows low efficiency in photochemical processes due to high electron hole pair recombination and photocorrosion. Recently Bi2O3 TiO2 composites were developed, which responded to visible light ( ≥ 400 nm) and displayed good photochemical stability [2]. In this work we prepared Bi2O3 TiO2/ITO multilayer films by dip coating from aqueous Bi(III) and Ti(IV) sols oxyhydroxides stabilized at 400 °C. The bismuth(III) oxide sols in aqueous phase (particle diameter 220 nm) were prepared by the precipitation peptization method, using Bi(OAc)3 and Tween 80 as precursor and stabilizer, respectively. The TiO2 sols were also prepared by following a precipitation peptization formulation previously developed (particle diameter 60 nm) [3]. The photoelectrochemical properties of the films were studied by voltammetric and photocurrent measurements using a conventional 3 electrode cell with a NaClO4 0.1 M solution (pH 8.5 adjusted with NaOH). Their photoelectrocatalytic activity was evaluated in the degradation of salicylic acid using visible light radiation. The photocurrent measurements showed that Bi2O3 TiO2/ITO films exhibited higher response to the visible light ( > 400 nm) than TiO2/ITO films (used as reference), producing higher steady state photocurrent. This increase in photocurrent is related to enhanced photoelectrocatalytic degradation of salicylic acid