Study on photocatalytic deposition of bismuth onto nanocrystalline TiO2 by quartz crystal microbalance and electrochemical method

In situ techniques of quartz crystal microbalance (QCM), differential pulse voltammetry (DPV) and amperometric measurement were employed to investigate the adsorption Bi(III) ions and the photocatalytic deposition Bi process at the surface of nanocrystalline TiO2. It was obtained that the adsorption of Bi(III) ions onto nanocrystalline TiO2 accords with the pseudo-second-order reaction and the reaction rate constant k was about 13.3 g mol−1 min−1. In addition, the photocatalytic deposition of Bi onto the surface of TiO2 was further investigated. It was found that photocatalytic deposition rate at the surface of TiO2 was enhanced by increasing pH value or initial concentration of Bi(III) ions. The influence of organic hole-scavegeners on the photocatalytic deposition of Bi was also investigated, and it was obtained that formic acid may be the best for the photocatalytic reduction of Bi. The mass ratio between the Bi(III) and Bi metal deposition was calculated as 7.48:1. Therefore, it can be concluded that QCM, DPV and amperometric measurement may be effective and reliable for the investigation of the photocatalytic deposition of Bi onto the surface of nanocrystalline TiO2.