Preparation And Photocatalytic Activity Of BaTiO₃ In Response To Visible Light

The rapid development of society and economy is accompanied by increasingly severe energy and environmental problems.In order to solve these problems,semiconductor photocatalytic technology is a promising research direction in the future.It can decompose water into hydrogen through semiconductor photocatalysis,and can also photodegrade organic pollutants.Most of our common photocatalytic materials can only absorb most of the photons in the ultraviolet region of sunlight due to their wide bandgap.Therefore,reducing the bandgap of materials to improve the light absorption capacity of materials is an important way to enhance the photocalalytic activity.As a popular semiconductor photocatalytic material,BaTiO3 also has the inherent disadvantages of most metal oxide semiconductors.In order to improve its photocatalytic performance,ion doping,as an important way to reduce the bandgap,can not only regulate the internal electronic structure,but also adjust the thermodynamic and kinetic requirements of its photocatalytic reaction.In the first part of this paper,Mo-doped BaTiO3 semiconductor powder was prepared by solid phase method,and Pt-loaded BaTiO3 powder was prepared by optical photoreduction method.Mo-doped BaTiO3 powders exhibited enhanced ability of light absorption and improving photocatalytic activity.The absorption edge of 2 at%Mo-doped BaTiO3 showed a significant redshift to the visible light range at about 500nm,compared with the pure BaTiO3 at about 400nm.Under simulated sunlight irradiation and with 0.4wt%Pt deposition,BaTiO3 doped with 2 at%Mo exhibits a hydrogen evolution rate of 63 ?mol g-1h-1,about 2 times improvement in comparison to pure BaTiO3(35 ?mol g-1h-1).Combined with the experiment tests and first-principles calculations,we investigated the influence mechanism about improving photocatalytiy,which provide an effective method into understanding the bandgap engineering,and also present useful direction to apply first-principles calculations in screening dopants with enhanced visible-light activity.In the second part of this paper,BaTiO3 semiconductor powders co-doped with Cr and V elements were prepared by solid phase method,and all BaTiO3 samples loaded with Ag particles were prepared by photoreduction method.After Cr doping into BaTiO3,the light absorption performance of BaTiO3 powders shifted to the visible light range at about 500nm.After Cr and V co-doping,the light absorption performance of BaTiO3 powders shifted to the visible light range at about 550nm.Through the photodegradation of methyl orange test,it was found that the degradation rate of pure BaTiO3 in 3 hours were 16%,the degradation rate of Cr-doped BaTiO3 in 3 hours were 25%,the degradation rate of Cr and V co-doped BaTiO3 in 3 hours were 40%,which exhibited enhanced visible light photocatalytic activity.Similarly,the combination with the first-principles calculation provides an effective way for us to analyze the synergistic effect of co-doped elements.