Huiling Li,Li Tian,Shuning Yang,Chao Li,Ruidan Li,Yujia Song,Yanjia Guo,Xuwen Li
To sensitively monitor trace-level of malathion (MAT) in vegetable samples, an ultrasensitive solid-state electrochemiluminescence (ECL) sensor was proposed based on TiO 2 @CdSe and Ru(bpy) 3 2+ @Ag NPs. In this system, the introduction of Ag NPs enhanced the initial ECL signal of Ru(bpy) 3 2+ - tripropylamine (TPrA). When TiO 2 @CdSe was introduced into the system, the ECL signal was further enhanced, which may be due to the synergistic effect of the two complexes. Based on the fact that the addition of MAT causes ECL strength to decrease, a ECL sensor for the ultrasensitive trace detection of MAT has been successfully established. Under the optimized conditions, a wide liner detection range of MAT concentrations from 4.0 × 10 −14 to 4.0 × 10 −9 mol L −1 and a low detection limit (S/N = 3) of 1.3 × 10 −14 mol L −1 were obtained. The ECL sensor has been applied to the detection of vegetable samples and satisfactory results were obtained.
Quantum dot (QD)/TiO2 composites are widely used materials in the field of photocatalysis. However, the influence of different exposed facets of TiO2 in composites on photocatalytic hydrogen evolution is rarely reported. In this work, CdSe QD–TiO2 composites with dominant {001} or {101} faceted anatase were synthesized and specifically characterized using X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Photocatalytic hydrogen evolution tests reveal that {001}-TiO2/CdSe QDs exhibit a 213.1- and 9.0-fold increase in photocatalytic activity compared to {001}-TiO2 and CdSe QDs, respectively. Notably, the photocatalytic activity of {001}-TiO2/CdSe QDs is 2.2 times higher than that of {101}-TiO2/CdSe QDs. Based on the results from UV-Vis diffuse reflectance spectroscopy, Brunauer–Emmett–Teller surface area testing, Mott–Schottky testing and steady-state and time-resolved emission spectroscopy, the main reason for enhanced photocatalytic activity is the faster electron transfer from CdSe QDs to {001}-TiO2 compared with to {101}-TiO2. This research on tailored facets in QD/TiO2 composites provides primary insights for the design of effective photocatalysts.
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