Preparation Of Oxynitride Type Perovskite Materials With Wide Spectral Response And Photoelectric Properties

Semiconductor materials have been widely applied in the domain of photoelectrochemical.However,for the traditional semiconductor materials,the utilization of solar energy is limited because of the narrow optical response range,usually confined to the UV region.Hence,it is necessary to construct a semiconductor material system with wide spectral response to further enhance the energy conversion efficiency of the photoelectric reaction.In recent years,the oxynitride type perovskite semiconductor material has attracted much attention due to its wide spectral response.In the present reports,oxynitride type perovskite semiconductor material can generally respond to a part of visible light,but the response capacity is still insufficient in the long wavelength visible light and infrared regions.In this paper,a new kind of LaMg1/3W2/3O2N oxynitride type perovskite material was prepared by simple chemical solution method.It was confirmed by its characterization that it had a wide response spectrum,especially in the infrared region.The material had high charge separation and transmission efficiency under visible and infrared light irradiation.In addition,comparing with pure C@TiO2,the composites made of LaMg1/3W2/3O2N and C@TiO2 were enhanced in hydrogen production.Specific research results are as follows:(1)A new type of oxynitride perovskite LaMg1/3W2/3O2N was successfully prepared by a simple citric acid method.XRD results show that the LaMg1/3W2/3O2N material is a solid solution formed between LaMg2/3W1/3O3 and LaWON2,and has a typical octahedral perovskite crystal structure.SEM characterization indicates that the crystalline grain size of the material is in the range of 50-70 nm.EDS,Elements Mapping and ICP were used to characterize the elements(La,Ma,W,O,N)in this material,and the proportion of each element was consistent with the stoichiometric ratio of LaMg1/3W2/3O2N.The UV-Vis absorption spectra show that the optical response range of LaMg1/3W2/3O2N material covers all the visible spectra and extends to the infrared region of 2500 nm.(2)The photoelectric performance test(I-V,EIS,I-t)shows that the doping of N makes the perovskite material obtain synergistic enhancement of photoelectric activity,charge transport and separation efficiency under visible light and infrared light.In addition,we also tried to combine LaMg1/3W2/3O2N with laboratory-made C@TiO2.The results showed that 1%LaMg1/3W2/3O2N-C@TiO2(ABO3-C@TiO2)composites obtained the best photocatalytic hydrogen production performance and cyclic stability.