Construction Of Semiconductor-based Electrochemiluminescence Systems For Pollutant Detection

Environme ntal po llutants s uch as persistent organic pollutants and heavy-meta lions could disturb or damage the normal phys io logical function after entering theorganis m, which would jeopardize the life of human beings. Therefore, it is necessaryto deve lop effic ient methods to track and monitor environmenta l pollutants in real time.Considering the special phys icochemical properties of nanomateria l, several methodsbased on the electroche miluminescence (ECL) of se miconductor nanomateria l and asimple and quick ana lys is on pentachloropheno l and cadmium were deve loped, whichcould provide new ideas for further research of environmenta l pollutants. The mainwork could be summarized as follows:(1) Electrochemiluminescence detection of pentachlorophenol with use of CdSquantum dots-graphene-carbon nanotubes composite (CdS/GR/CNTs): Chemica l bathdeposition was employed to depos it CdS QDs on GR/CNTs film and the resultspresented a homoge neous and dense distribution of CdS within an average size in theSEM image. With multista ge signal amp lification of coreactant K2S2O8and GR/CNTsfilm, the ECL signa l of the as-prepared composite was shown in a high leve l. Under theoptima l conditions, a detection limit of1.0×10-12M was achieved within a linear rangeof1.0×10-12to1.0×10-9M when detecting pentachlorophenol. Ideal recovery resultshave been revealed in detection of practical samp les, which could manifest that thismethod has met the require ments of practical test.(2) Electrochemiluminescence detection of pentachlorophenol with use of CdSquantum dots-graphene-TiO2nanotubes composite (CdS/GR/TiO2NTs): Oxidegraphene on TiO2nanotube arrays was reduced to grapheme (GR) throughphoto-reductio n. GR could accelerate the trans fer of electron between CdS andcoreactant and improve the ECL performance of CdS quantum dots. Due to a highspecific surface area of graphene and TiO2nanotube arrays, the pentachloropheno l inthe solution was easily absorbed on the surface of modified electrode to be detection,which has demonstrated a high sens itivity of the method. The limit o f detection wouldbe1.0×10-11M (S/N=3).(3) Electrochemiluminescence detection of cadmium ion with use ofAg-AgBr-TiO2nanofiber: Ag-AgBr-TiO2nano fiber was easily prepared throughelectrospinning. Based on the quenching effect of Cd2+, a quick trace detection of Cd2+ was achieved within a linear range of3.6×10-8to3.6×10-6g·L-1. Due to the stability ofnanofiber, the as-prepared composite showed a highly stable ECL performance andgood repeatability in detecting Cd2+. This method has several advantages inc lud ingfacile preparation, low cost and high sensitivity, which could generate a brand newapproach for the analys is of Cd2+.