Preparation And Visible-light Photocatalytic Performance Of AgBr/GO/AgFeO₂

The energy crisis and environmental pollution have been paid more and more attention by the international community.In order to realize social sustainable development,it is urgent to explore environmental protection technologies for pollutant degradation and clean energy supply.Solar energy is pollution-free,inexhaustible and unlimited renewable resource,which provides a bright prospect for photocatalytic technology.With the vigorous development of photocatalytic technology,it is imperative to develop excellent photocatalysts.A variety of silver-based semiconductor photocatalysts have attracted extensive attention in recent years due to their characteristics on narrow band gap and visible-light response.In this paper,AgFeO₂and AgBr/GO/AgFeO₂were prepared.Through a series of characterization techniques,the effects of synthesis and modification conditions on the structure,morphology,magnetic properties,chemical composition and optical properties of AgFeO₂and AgBr/GO/AgFeO₂were explored.Tetracycline was used as the target pollutant to explore its photocatalytic oxidation ability,and silver nitrate was used as the reaction substrate to explore the photocatalytic reduction of silver ions.At the same time,two reaction mechanisms were proposed.The main conclusions are as follows:（1）AgFeO₂was synthesized by simple co-precipitation method.AgFeO₂is composed of 2H and 3R crystal forms.The light absorption edge of AgFeO₂is about800 nm.the valence band position,conduction band position and band gap of AgFeO₂are calculated to be 2.15 eV,0.39 eV and 1.76 eV,respectively.The effects of calcination temperature on the structural stability,micro morphology,specific surface area,magnetic properties and optical properties of AgFeO₂were investigated.The results show that AgFeO₂has strong high temperature thermal stability and can maintain structural stability till 500℃;With the increase of calcination temperature,the specific surface area of AgFeO₂decreased;The calcination temperature has almost no effect on the magnetic properties and slightly inhibits the photocatalytic activity of AgFeO₂.（2）The AgBr/GO/AgFeO₂composite heterojunction was constructed by graphene oxide（GO）,AgBr and AgFeO₂.It is found that the introduction of GO and AgBr can significantly improve the visible-light photocatalytic activity of AgBr/GO/AgFeO₂.When the molar ratio of AgBr to AgFeO₂is 1:1.5,the visible-light photocatalytic performance of AgBr/GO/AgFeO₂is the best.（3）When exposed to visible light for 30 min,AB/GO/AFO-1.5 can remove 86%tetracycline from deionization water,which is the twice of AgFeO₂and 50 times of GO/AgBr,respectively.The removal rates of tetracycline from the Yellow River and tap water decrease to 72%and 66%.In addition,Ag（Ⅰ）in aqueous solution can be effectively photocatalytic reduced by AB/GO/AFO-1.5,and the reduction capacity is28 mg/g.