Controllable Preparation of Highly Crystalline Sulfur-Doped Π-Conjugated Polyimide Hollow Nanoshell for Enhanced Photocatalytic Performance.

In this study, a series of highly crystalline π-conjugated polyimide photocatalysts with porous nano hollow shell (HSPI) was prepared for the first time by the hard template method by adjusting the addition ratio of the template precursor. SiO2 nanospheres not only serve as template agents but also as dispersants to make precursors of SPI more uniform, and the degree of polymerization will be better, resulting in significantly enhanced crystallinity of HSPI relative to bulk SPI (BSPI). More strikingly, it is found that HSPI has a larger specific surface area, stronger visible light absorption, and higher separation efficiency of photogenerated electron and hole pairs compared with BSPI by various spectral means characterization analysis. These favorable factors significantly enhanced the photocatalytic degradation of methyl orange (MO) by HSPI. This work provides a promising approach for the preparation of cheap, efficient, environmentally friendly, and sustainable photocatalysts.

Fabrication of high-performance cell-imprinted polymers based on AuNPs/MXene composites via metal-free visible light-induced ATRP.

Cell-imprinted polymers (CIPs) for yeasts were fabricated via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP) on the surface of a glassy carbon electrode (GCE) which had been modified with gold nanoparticles (AuNPs)/MXene (Ti3C2Tx) composites. Here, the AuNPs/Ti3C2Tx composites form a macroporous structure, which could improve the electron transfer rate of the materials and facilitate the leaving or rebinding of cells. Methacrylic acid (MAA) and N,N'-methylene bis-acrylamide (MBA) were selected as the functional monomer and cross-linker of CIPs, because they could form efficient hydrogen bonding with mannan from yeast cell walls. The obtained electrode (CIPs/AuNPs/Ti3C2Tx/GCE) was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Further experiments indicated that the CIPs/AuNPs/Ti3C2Tx/GCE electrode could be utilized as an electrochemical biosensor to determine yeast cells by differential pulse voltammetry (DPV). The linear response range was 1.0 × 102 to 1.0 × 109 cells per mL and the detection limit was 20 cells per mL (S/N = 3). The CIPs/AuNPs/Ti3C2Tx/GCE electrode also showed good selectivity, repeatability, reproducibility, and regeneration. Finally, the proposed sensor was used to detect yeast cells in commercial samples of Saccharomyces boulardii sachets by a standard addition method. The obtained recovery was from 96.9 to 104.8% showing its potential applications in clinical and diagnostic research.

MXene-based composites as an electrochemical sensor for ultrasensitive determination of ofloxacin.

Sensitive determination of ofloxacin (OFL) is very essential for human health and environmental protection. Here, a novel composite of gold nanoparticles(nAu)@MXene(Ti3C2Tx)/poly-p-aminobenzene sulfonic acid (PABSA) was fabricated on the surface of glassy carbon electrode (GCE) and used to sensitively determine OFL. The results of experiments showed that the obtained nAu@Ti3C2Tx/PABSA/GCE electrode could be used as an electrochemical sensor to directly detect ofloxacin (OFL) by differential pulse voltammetry (DPV). Under the optimal conditions, the proposed electrode displayed a broader linear range and a lower detection limit (LOD) for OFL determination when it was compared to those similar sensors. The linear range was from 5.0 × 10-8 to 5.0 × 10-4 mol/L and the LOD was 3.7 × 10-8 mol/L (S/N = 3). The nAu@Ti3C2Tx/PABSA/GCE electrode also showed good selectivity, repeatability, and reproducibility. Finally, the proposed electrode was used to detect OFL in commercial samples by the standard addition method. The obtained recovery was from 97.3% and 105.7% showing its potential applications in actual sample analysis.

Construction of α-Fe2O3/Sulfur-Doped Polyimide Direct Z-Scheme Photocatalyst with Enhanced Solar Light Photocatalytic Activity.

A novel two-dimensional α-Fe2O3/sulfur-doped polyimide (FO/SPI) direct Z-scheme photocatalyst was successfully constructed by a facile thermal treatment method. The effects of α-Fe2O3 nanosheets on the morphology, chemical structure, and photoelectronic properties of FO/SPI composites were systematically characterized by different spectroscopic means. These methods include X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, transient fluorescence spectra, and so forth. It was confirmed that the small amounts of α-Fe2O3 can availably facilitate exfoliation of bulk SPI, resulting in a transformation of SPI from bulk to 2D layered composite that illustrates tight interface through the coordination Fe-N bond and an all-solid-state direct Z-scheme junction. Thus, the transfer and separation efficiency of photogenerated electron/hole pairs were significantly enhanced, which greatly promoted improvement of the photocatalytic activity of the FO/SPI composite for methyl orange degradation under solar light. This work provides a new approach to constructing efficient inorganic-organic Z-scheme photocatalyst based on strong interface interaction.