Preparation And Photocatalytic Activity Of BiOCl Photocatalyst Modified With Pt In Different Valence States

Semiconductor photocatalysis technology can be used to solve energy crisis and environmental pollution by using solar energy.The key of semiconductor photocatalytic technology is to research and develop high-efficiency and stable semiconductor materials.BiOCl as a new type of semiconductor photocatalytic materials,which possesses unique open layered structure and indirect band gap characteristics not only in favor of the separation efficiency of electronic-hole and transfer,but also endowed with good optical and electronic properties,make it have excellent catalytic activity and stability.However,how to further improve the photocatalytic activity of BiOCl has become a key issue in the study of photocatalysis.In the field of photocatalysis,the research on the precious metal Pt has been widely studied by researchers.Among all precious metals,Pt has the largest working function value（ca.5.65 eV）and more prominent electron capture capability,so Pt is regarded as a good catalyst in the field of catalysis.However,there are few studies on the influence of different valence states and forms of precious metal Pt on carrier catalysts.Therefore,we studied the effect of Pt different valence states and morphology on BiOCl photocatalysis.This paper on the basis of BiOCl photocatalytic materials,by regulating the preparation conditions and the carrier of surface properties enable Pt to exist on the surface of BiOCl with different valence states and forms.The samples were characterized by XRD,SEM,TEM,XPS,UV-vis DRS,PL and so on.The photocatalytic activity and cyclic stability of the samples were evaluated by the degradation experiments of MO under simulated sunlight irradiation.The effect of platinum with different valence states and morphology on photocatalytic performance of BiOCl was studied and reaction mechanism of the photocatalytic reaction were discussed.The main results of the paper are as follows:（1）A series of Pt/BiOCl and Pt O/BiOCl photocatalysts were prepared by using a immersion-light reduction method.XPS characterization proved that platinum was present in Pt/BiOCl and Pt O/BiOCl photocatalyst respectively with Pt and PtO.The photocatalytic activity of Pt/BiOCl and PtO/BiOCl were compared by the degradation experiment of MO under simulated sunlight irradiation.The results showed that compared with pure BiOCl photocatalyst,the activity of Pt/BiOCl and PtO/BiOCl photocatalysts were both improved.The PtO/BiOCl catalyst showed better photocatalytic activity,of which 0.8%PtO/BiOCl had the best photocatalytic activity.The main reason is that the Pt O with BiOCl formed heterojunction structure,The efficiency of light absorption was enhanced,and the effective separation of photonic electrons and holes were promoted.As well as the smaller and more uniform PtO nanoparticles active sites enhanced the photocatalytic activity of 0.8%PtO/BiOCl photocatalyst.（2）We used BiOCl as the carrier with bismuth vacancy on the surface,and the PtO nano-particles was successfully loaded on the surface of BiOCl by a simple impregnated-light reduction method under the weak alkaline condition（pH=8）,named PtO/Pt-BiOCl.The sample of Pt O/Pt⁴⁺-BiOCl,which Pt⁴⁺doped into bismuth vacancy,meanwhile PtO loading on the surface of BiOCl was successfully synthesizd by a simple impregnated light reduction method under the strong alkaline condition（pH=12）.The experimental results showed that the degradation rate constant of the sample PtO/Pt⁴⁺-BiOCl(0.154 min^-1)was 8.6times of the degradation rate constant of the sample BiOCl(0.0179 min^-1)and was 4 times of the degradation rate constant of PtO/Pt⁴⁺-BiOCl(0.038min^-1).Combining experiment and characterization analysis,We hypothesized the formation mechanism and photocatalytic mechanism of Pt O/Pt⁴⁺-BiOCl.It was due to synergistic effect of Pt⁴⁺impury and loaded of PtO that the photocatalytic activity of BiOCl was enhanced.