Shell-Isolated Nanoparticle-Enhanced Electrochemiluminescence.

Enhanced electrochemiluminescence (ECL) aims to promote higher sensitivity and obtain better detection limit. The core-shell nanostructures, owing to unique surface plasmon resonance (SPR) enabling distance-dependent strong localized electromagnetic field, have attracted rising attention in enhanced ECL research and application. However, the present structures usually with porous shell involve electrocatalytic activity from the metal core and adsorption effect from the shell, which interfere with practical SPR enhancement contribution to ECL signal. Herein, to exclude the interference and unveil exact SPR-enhanced effect, shell-isolated nanoparticles (SHINs) whose shell gets thicker and becomes pinhole-free are developed by modifying pH value and particles concentration. Furthermore, allowing for the distribution of hotspots and stronger enhancement, excitation intensity and ECL reaction layer thickness are mainly investigated, and several types of SHINs-enhanced ECL platforms are prepared to fabricate distinct hotspot distribution via electrostatic attraction (submonolayer) and a layer-by-layer deposition method (monolayer). Consequently, the strongest enhancement up to ≈250-fold is achieved by monolayer SHINs with 10 nm shell, and the platform is applied in a "turn-off" mode sensing for dopamine. The platform provides new guidelines to shell preparation, interface engineering and hotspots fabrication for superior ECL enhancement and analytical application with high performance.

In situ homogeneous formation of Au@AgNPs for the rapid determination of formaldehyde residues by surface-enhanced Raman spectroscopy coupled with microhydrodistillation.

The reaction of formaldehyde (HCHO) with the solution containing Au nanoparticles and [Ag(NH3)2]+ through Tollens' reaction is described to form Au@Ag nanoparticles (Au@AgNPs), which are used as a SERS enhancement material. A minimized hydrodistillation device with air condense is designed to obtain a clean aqueous background for SERS analysis and simplified pretreatment process. A good linear relationship is found between the SERS signals and the concentration of HCHO in the range 0.3 to 55 mg L-1 when p-aminothiophenol (p-ATP) is selected as the Raman signal molecule, and the detection limit is 0.08 mg L-1. Stable SERS signals could be achieved due to both homogeneous formation of Au@AgNPs and clean aqueous background. The relative standard deviation (RSD) of 15 batches samples is found to be 7.1%. The proposed approach has successfully been applied to the determination of HCHO residues in beer samples with low interferences. The recoveries of spiked samples are in the range 96 to 117% with RSDs lower than 5.9%. Graphical Abstract.

Development of a sequential injection analysis device and its application for the determination of Mn(II) in water.

A sequential injection analysis device has been developed and applied for the automated determination of Mn(II) in environmental water samples. Differential pulse cathodic stripping voltammetry is selected as the electrochemical detection method. The device consists of several electronic equipment. The electrochemical flow cell was designed for replacing the traditional three-electrode system and introducing high reproducibility. An electrochemical analyzer saddled with laboratory-programmed software written by Embarcadero Delphi 10.2. For higher current response, various determination parameters such as the flow rate, the medium pH, the deposition potential and the thickness of gasket in the electrochemical flow cell have been optimized. Under the optimal conditions, the detection limit (3σ/slope) of 0.63 µg L-1 and a calibration curve (R2 = 0.9987) of current response and Mn(II) concentration from 2.5 µg L-1 to 200 µg L-1 could be achieved. The device was successfully applied to the determination of trace Mn(II) in environmental water samples, and in continuous real-time monitoring of Mn(II) variations in tap water for 14 days. The results are consistent with the reference method and the average recovery is found to be 95.2%-101.4%. The device shows high sensitivity and reproducibility in the determination of Mn(II), and presents a great potential for on-site and real-time detection of metal ions where rapid, low-cost and low-volume analysis is required.

Unveiling the interfacial electrochemiluminescence behavior of lead halide perovskite nanocrystals.

In this study, a three-phase heterostructure interface including glassy carbon (conducting medium), CsPbBr3 perovskite nanocrystals (PNCs, emitter) and acetonitrile (electrolyte) is constructed for fully investigating the interfacial electrochemiluminescence (ECL) behavior of CsPbBr3 PNCs. We find that these interfaces serve as bridges for efficient electron-hole transfer during the ECL process. As a proof of concept, the increase of the heterostructure interface area will accordingly enhance the ECL intensity of CsPbBr3 PNCs. About seven-fold enhancement of the ECL intensity could be achieved when the interface area has triple-fold increase, which provides a new perspective to construct more efficient ECL systems via interface engineering.

Enhancing the Stability of CH3NH3PbBr3 Nanoparticles Using Double Hydrophobic Shells of SiO2 and Poly(vinylidene fluoride).

The instability of lead halide perovskites (LHPs) has tremendously hindered their practical applications. Although some examples on encapsulating LHPs into a SiO2 shell have been reported, these SiO2-coated LHPs still suffer from limited stability. Herein, MAPbBr3 (MA = CH3NH3+) nanoparticles encapsulated in double hydrophobic shells of organic functionalized SiO2 and poly(vinylidene fluoride) (MAPbBr3@SiO2/PVDF) are successfully synthesized by infiltrating the MAPbBr3 precursor solution into hollow siliceous nanospheres and followed by PVDF capping. With the dual protection of SiO2 and PVDF, the MAPbBr3@SiO2/PVDF nanoparticles exhibit drastically improved stability against water and UV-light illumination. A white light-emitting diode with luminous efficiency up to 147.5 lm W-1 and a color gamut encompassing 120% of National Television System Committee in Commission Internationale de L'Eclairage 1931 color space has been demonstrated using the MAPbBr3@SiO2/PVDF nanoparticles as the green light source. This study enlightens new insights into the synthesis of highly stable LHPs-based core-shell-shell architectures toward their practical applications.