Self-assembly can offer a very powerful tool for the design of novel materials and many different templates have been found to direct the formation of microstructures. In this article, we report a simple method for the self-assembly of three-dimensional (3D) WO 3 nanotube bundles. It is demonstrated that not only can NaHSO 4 act as a reactant, but also, more importantly, it played multiple key roles in the self-assembly processes, while NH 4 HSO 4 and KHSO 4 have none of these functions at all. As suggested, at first, WO 3 ordered and layered structures can be generated by the hydrothermal reaction of NaHSO 4 with Na 2 WO 4 at 180 C, and then sodium ions (Na + ) inserted into the layer cause a continual curl of the WO 3 outer-slice by the repel force of static electricity between Na + ions and H + ions on the surface of the WO 3 slice. Herein, Na + ions can dramatically promote the formation of WO 3 single crystal slices, which are precursors of the self-assembly, and SO 4 2À ions can bridge the WO 3 slices as well as the nanotubes.In addition, it is found that the WO 3 nanotube bundles still keep their original aggregation after template removal, and the bundle can be disassembled gradually under a long treatment time of aqueous ultrasonication. Furthermore, the application in wastewater treatment of WO 3 nanotube bundles has been investigated.
Up to 0.61 V increase in the working potential was achieved by modifying the anthraquinone (AQ) molecular structure with a stronger electron-withdrawing cyano group.
Hydrogen sulfide is a highly toxic molecule to human health, but high-performance detection of it remains a challenge. Herein, we report an ultrasensitive photoelectrochemical (PEC) sensor for HS by modifying indium tin oxide (ITO) electrodes with Cd-doped amorphous TiO hollow spheres, which are prepared by templating against colloidal silica particles followed by a cadmium-sodium cation exchange reaction. The amorphous TiO hollow spheres act as both the probing cation carrier and the photoelectric beacon. Upon exposure to sulfide ions, the photocurrent of the functionalized photoanode proportionately decreases in response to the formation of CdS nanoparticles. The decreased photocurrent could be attributed to the mismatching bandgap between the amorphous TiO and CdS nanoparticles: the photoexcited electrons and holes from amorphous TiO are transferred to the conduction band and valence band of CdS, respectively, and then recombined. The decrease in photocurrent is linear with the concentration of sulfide ions in the range from 1 to 10 000 pmol L with a detection limit of 0.36 pmol L. Enabled by a unique sensitization mechanism, this PEC sensor features excellent performance in a wide linear range, high selectivity and sensitivity, high stability, and low fabrication cost.
Selectivity
is a crucial parameter for photoelectrochemical (PEC)
sensing in a practical setting. Despite the use of specific probes
such as aptamers, antibodies, and enzymes, coexisting interferences
can still result in inaccuracies in PEC sensing, especially for complex
biosample matrixes. Here we report the design of an Fe3O4@SiO2@TiO2 magnetic–optical
bifunctional beacon applied in a novel PEC sensor that can selectively
capture progesterone in complex biosamples, be magnetically separated
and cleaned, and be detected in pure phosphate buffer solution (PBS).
The magnetic separation strategy efficiently removes the complex coexisting
species from the modified electrode surface and drastically enhances
the selectivity of the as-designed PEC sensor. The as-designed PEC
sensor is cost-effective, easy to fabricate, highly selective and
sensitive, and highly reliable, making it a promising platform for
efficient aptasensing.
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