Search

Abstract: In order to compare the photocatalytic properties of TiO2, ZnO and their composite in the gas phase pollutant environment, nanocomposite with different mole ratios of TiO2/ZnO were designed to degrade gaseous formaldehyde. The results showed that the rate constant of TiO2 for formaldehyde degradation was 0.05min−1 which was two orders of magnitude larger than that of ZnO in our experiment. Through comprehensive analysis of UV–vis diffuse reflectance (UV–vis) spectra, photoluminescence spectra (PL) and energy band diagram, it was found that the differences of photocatalytic properties between ZnO and TiO2 may mainly originate from the increased recombination of photoinduced charges in ZnO. The photocatalytic properties of TiO2/ZnO composite for formaldehyde degradation were much worse than those of TiO2, while better than those of ZnO. The addition of a small amount of ZnO weakened the photocatalytic properties of TiO2. It may be attributed to that the recombination action of photoinduced electron–hole pairs in ZnO. [Copyright &y& Elsevier]

On the basis of combinatorial methodology and the idea of an equilateral ingredient triangle, the TiO2/ZnO/Fe2O3composite system including 66 ingredient points was designed. The photocurrents under different light sources and bias voltages were measured, and the photocurrent amplitude at 300 s was chosen as a parameter to evaluate the photoelectric response of the composite. To appraise the composition effect of the composite compared with pure materials, the quantitative formula of the composition effect has been provided for the first time in this paper. We found that not all the ingredient points demonstrated the enhanced composition effect in the as-designed ingredient triangle material library. The reasons of different composition effect for different ingredient points have been discussed in detail. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were used to investigate the phase structure and the grain morphology of the composite. [ABSTRACT FROM AUTHOR]

Highlights: [•] The calculation of IPCE for heterojunction used in photoconduction is established. [•] A TiO2/SnO2 composite system with 11 ingredient points is fabricated and tested. [•] The sample whose mole ratio is TiO2:SnO2 =2:8 have the best IPCE. [•] The best IPCE is attributed to the match of energy band and the conductive channel. [Copyright &y& Elsevier]

Abstract: In this study, a novel photoelectrocatalytic (PEC) flat-plate type device used in the gas-phase was fabricated by the technology of screen printing. The TiO2/WO3 nanocomposite (2:8 in mole ratio) was prepared by a simple milling-anneal method and printed onto the device. The obtained device was attempted to investigate the PEC performance by applying low biases for degrading the volatile organic compounds (VOCs). The apparent pseudo-first-order kinetic model was used to describe the degradation process. The results showed that the applied low bias had a distinct enhancement effect on the degradation activity compared to photocatalytic (PC) degradation. The PEC degradation rate under UV-light (365nm) irradiation by applying only 0.2V bias was about 12.28×10−3 min−1, which was 2.42 times of PC degradation rate. Under the blue-light (475nm) irradiation, the composite still had good degradation efficiency and the rate constant was about 2.6×10−3 min−1. Furthermore, the explanation was proposed that the degradation activity of TiO2/WO3 composite could show obviously enhancement for gas-phase PEC process by applying bias at a very low level, compared to pure TiO2. [ABSTRACT FROM AUTHOR]