Molten-salt fabrication of (N,F)-codoped single-crystal-like titania with high exposure of (001) crystal facet for highl
- PDF / 605,775 Bytes
- 11 Pages / 584.957 x 782.986 pts Page_size
- 107 Downloads / 172 Views
Hongwei Huangb) School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China
Zhanhu Guoc) Chemical and Biomolecular Engineering Department, University of Tennessee, Knoxville, Tennessee 37996, USA
Zhaohui Li
Geosciences Department, University of Wisconsin – Parkside, Kenosha, Wisconsin 53144, USA (Received 8 January 2018; accepted 6 April 2018)
Single-crystal-like TiO2 is claimed to be a very promising material among various catalysts. In this study, the (N,F)-co-doped single-crystal-like TiO2 was prepared by a new molten mixing process in which the mixed nitrates were used both as a morphology modifier and an N-doping agent at the same time. The prepared samples also had well-developed (001) facet due to the addition of HF. The HF can also be an F doping agent to the material. The co-doping of N and F can diminish the band gap of TiO2 from 3.05 to 2.93 eV, therefore visible light can be used effectively by the material. In addition, NO and fluorine ions existing on the surface of the sample can also help its photocatalyticity. Therefore, the photocatalytic performance of the as-prepared sample was effectively improved.
I. INTRODUCTION
Titanium dioxide (TiO2) has now become one of the most efficient and widely used materials in the field of photocatalysis. It was found to display photocatalytic activities under ultraviolet (UV) light by Fujishima and Honda in 1972.1 In 1976, Carey et al. began the study of photocatalytic degradation of pollutants using TiO2 to remove chlorine from polychlorinated biphenyls under UV irradiation.2 In 1977, Frank et al. successfully converted CN to OCN using TiO2 as a photocatalyst.3 Presently, photocatalytic technology has been considered as one of the most effective ways to solve the problems of energy and environmental pollution.4,5 TiO2 has many advantages including low cost, nontoxicity, long-term stability, and high photoactivity.6–11 However, there are still some obstacles toward its broader applications in photocatalysis and other fields. One of the difficulties to use TiO2 in practice is its wide band gap of about 3.2 eV, which means that it can only be activated by UV irradiation. UV light has a wave length below 380 nm making up only about 5% of the solar energy.12,13
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] c) e-mail: [email protected] DOI: 10.1557/jmr.2018.106
Therefore, it is very important to improve the visible light activity of the photocatalyst. Preparation of titania with high energy crystal facets is a very important method to increase the electron hole pair separation and the photocatalytic activity of the catalyst.14,15 In recent years, the synthesis of photocatalytic TiO2 with high energy (001) crystal facet has become a research hotspot.16–20 For example, Yang et al. in 2008, for the first time, successfully prepared anatase crystal TiO2 with a (001) facet exposure rate of 10%.21 After that, Yang synthesized TiO2 with a 64% (001) facet exposure rate and the TiO2 pho
Data Loading...
