Au And Bi₂S₃ Decorated TiO₂ Nanotube Arrays Towards Boosting Photocatalytic Degradation Of Dyes And Fluorescence Detecting Fe³⁺ Ions

With the development of the economy and the advancement of industry,environmental problems have become more and more serious,especially the wastewater pollution caused by the textile printing and dyeing industry,which has become one of the hot issues that need to be solved.In order to alleviate the pressure on the environment,researchers are looking for efficient photocatalysts to reduce the burden of environmental pollution.TiO2 nanotube arrays(TiO2 NTAs)are used as excellent nanomaterials in the field of photocatalysis because of their large specific surface area,high surface energy,easy recycling and directional charge transport.Therefore,in this paper,TiO2 NTAs were prepared by two-step anodization.Then,the Au/Bi2S3@TiO2 NTAs composite electrode was formed by using a narrow band gap Bi2S3 and the noble metal Au decorated on TiO2 NTAs.Due to the local surface plasmon resonance(LSPR)effect of Au and the heterojunction formed by TiO2 and the efficient separation of electrons-holes is promoted,so that the composite exhibits enhanced solar absorption and excellent photoelectochemical(PEC)performance.Under irradiation of UV and visible light,the degradation rate of Au/Bi2S3@TiO2 NTAs to methylene blue(MB)was about 70%and 60%,respectively.The degradation rate of acid orange was about 50%and 45%,respectively.The degradation rate of acid blue was about 70%and 45%.Compared with the pure TiO2 NTAs electrode,the photocatalytic performance of the Au/Bi2S3@TiO2 NTAs composite electrode is greatly improved and exhibits excellent photostability.In addition,the synthesized nanocomposites have high selectivity to Fe3+ ions due to better binding affinity between Bi2S3,TiO2 and Fe3+ ions.The number of binding sites("n")of Au/Bi2S3@TiO2 NTAs was estimated to be 1.41 from the double logarithmic regression method,and the calculated value "K" was 1862 M-1.The higher values of "K" and "n"indicate that Au/Bi2S3@TiO2 NTAs have a better interaction with Fe3+ ions to support the formation of ground state complexation.The intensity of the fluorescence emission decreases linearly over a concentration range of 30 ?M to 5000 ?M,and the detection limit of the synthetic sensor is 0.221 ?M.