Construction Of Mace Rod Like ZnO/PbTiO₃ Micro Nano Structure And Its Piezoelectric Photocatalytic Performance

Semiconductor oxide zinc oxide(ZnO)has piezoelectric and photocatalytic properties,it is non-toxic and low preparation cost,it has broad application prospects in the field of water treatment.However,ZnO has a narrow light absorption range and low carrier transfer efficiency,resulting in its low degradation efficiency.Tetragonal lead titanate(PbTiO3)is a typical piezoelectric material which has high spontaneous polarization intensity.The piezoelectric coefficient d33(79 pC/N)is 6 times that of ZnO.When it is excited by small energy in the external environment,a large piezoelectric field can be generated in the crystal.Therefore,this paper proposes to composite ZnO nanorods(ZnO NRs)on the surface of lead titanate nanofibers(PbTiO3 NWs),constructing mace rod like micro nano structure.The dynamic piezoelectric field generated by PbTiO3 under ultrasound and the built-in electric field generated by pn junction at the interface between PbTiO3 and ZnO are used to realize the effective separation of photogenerated carriers in ZnO,therefore,the photocatalytic activity of ZnO is improved.On this basis,silver oxide nanoparticles(Ag2O NPs)were further deposited on the surface of ZnO NRs to broaden the visible light absorption range of ZnO,the mechanism of piezoelectric photocatalysis under the cooperation of double piezoelectric field and double heterojunction will be explored.The main work includes the following two aspects:(1)Firstly,PbTiO3 NWs was prepared by hydrothermal method,and then mace rod like ZnO/PbTiO3 micro nano structure was prepared by secondary hydrothermal method.Study the effects of different zinc sources,growth solution concentration and hydrothermal time for the morphology,structure and piezoelectric photocatalytic performance of the samples.The results show that when zinc nitrate is used as zinc source,the concentration of growth solution is 0.05 M(mol/L)and hydrothermal for 8 h,the sample is wurtzite phase ZnO NRs with a length of about 580 nm,which grows vertically and evenly on the surface of tetragonal PbTiO3 NWs.The piezoelectric photocatalytic efficiency of the sample for methyl orange solution is 64%,which is 48%higher than that of ZnO,and the degradation rate of Rhodamine B solution is 98%in 90 min.The built-in electric field of pn junction at the interface between ZnO and PbTiO3 cooperate to the double piezoelectric electric field generated by ZnO/PbTiO3 deformation to accelerate the separation of photogenerated carriers in ZnO.(2)Based on the ZnO/PbTiO3 of micro nano structure,Ag2O NPs is loaded on the surface of ZnO/PbTiO3 by chemical precipitation method.The effects of Ag2O loading on the morphology,structure and piezoelectric photocatalytic properties of ZnO/PbTiO3 were studied.The results show that when the loading amount is 7 wt%,Ag2O NPs with diameter of about 46 nm are evenly distributed on the surface of ZnO NRs without agglomeration.The piezoelectric photocatalytic efficiency of the sample is 93%,which is 30%higher than that of ZnO/PbTiO3.The degradation rate of Rhodamine B solution reaches 99%in 120 min.After loading Ag2O NPs,the light absorption of ZnO/PbTiO3 at 400-800 nm is enhanced,the morphology and structure of the samples did not change significantly after four cycles degradation under the condition of light and low-speed stirring,and the degradation efficiency remained at 78%.Under the synergy of double heterojunction and double piezoelectric field,space charges will not shield the built-in electric field,the photocatalytic activity of ZnO/PbTiO3 is significantly improved.