Graphene-amplified electrogenerated chemiluminescence of CdTe quantum dots for H2O2sensing

Photoelectrochemical sensing and mechanism investigation of hydrogen peroxide using a pristine hematite nanoarrays

In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (α-Fe₂O₃) nanoarrays on fluorine-doped SnO₂ glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-Fe₂O₃ photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-Fe₂O₃ photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H₂O₂) in aqueous solutions, with a low detection limit of 20 μM (S/N = 3) and wide linear range (0.01-0.09, 0.3-4, and 6-16 mM). Additionally, the α-Fe₂O₃ photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H₂O, H₂O₂ possesses much more fast reaction kinetics over α-Fe₂O₃ surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H₂O₂ in aqueous solution, will stimulate us to further optimize the surface structure of α-Fe₂O₃ to gain highly efficient α-Fe₂O₃ based sensors.

Advances in chemiluminescence and electrogenerated chemiluminescence based on silicon nanomaterials

Since 1950, when chemiluminescence (CL) of siloxane upon treatment with strong oxidants was discovered by Kurtz, many silicon-based nanomaterials with different elements, specific molecules, shapes and sizes have been developed as light emitters, energy acceptors, and catalyzers to provide valuable CL and electrogenerated CL (ECL) detection platforms in analytical chemistry fields. This review mainly focuses on the recent development of their mechanisms and sensing methodologies for small molecules, free radicals, ion, enzyme, protein, DNA, cancer cells, and metabolites based on specific reactions such as aptamer sensing and enzymatic reaction. Additionally, the future trend is discussed.

Enhanced electrochemiluminescence from reduced graphene oxide-CdTe quantum dots for highly selective determination of copper ion

An electrochemiluminescence (ECL) sensor based on reduced graphene oxide-CdTe quantum dots (RGO-CdTe QDs) composites for detecting copper ion (Cu²⁺ ) was proposed. The ECL behaviours of the RGO-CdTe QD modified electrode were investigated with H₂ O₂ as the co-reactant. Quantitative detection of Cu²⁺ was realized as Cu²⁺ could effectively quench the ECL signal of the RGO-CdTe QDs. A wide linear range of 1.00 × 10^-14 to 1.00 × 10^-4  M (R = 0.9953) was obtained under optimized conditions, and a detection limit (S/N = 3) was achieved of as low as 3.33 × 10^-15  M. The proposed sensor also exhibited good stability and selectivity for the detection of copper ions. Finally, the analytical application of the proposed sensor was also evaluated using river water.

Luminol and gold nanoparticle-co-precipitated reduced graphene oxide hybrids with long-persistent chemiluminescence for cholesterol detection

Luminol and AuNP dual-functionalized rGO hybrids (rGO/AuNP/luminol) have been synthesized to generate long-persistent chemiluminescence, which can be used as a chemiluminescent biosensing platform for the detection of cholesterol.

Optimising electrogenerated chemiluminescence of quantum dots via co-reactant selection

We demonstrate that for quantum dot (QD) based electrochemiluminescence (ECL), the commonly used co-reactant does not perform as effectively as potassium persulfate. By exploiting this small change in co-reactant, ECL intensity can be enhanced dramatically in a cathodic-based ECL system. However, TPA remains the preferential co-reactant-based system for anodic ECL. This phenomenon can be rationalised through the relative energy-level profiles of the QD to the co-reactant in conjunction with the applied potential range. This work highlights the importance of understanding the co-reactant pathway for optimising the application of ECL to bioanalytical analysis, in particular for near-infrared (NIR) QDs which can be utilised for analysis in blood.

Graphical Abstract

Non-enzymatic sensor based on a glassy carbon electrode modified with Ag nanoparticles/polyaniline/halloysite nanotube nanocomposites for hydrogen peroxide sensing

Ag nanoparticles/polyaniline/halloysite nanotube nanocomposites were synthesized and used for fabricating nonenzymatic H₂O₂ sensor.

Microwave-assisted facile synthesis of yellow fluorescent carbon dots from o-phenylenediamine for cell imaging and sensitive detection of Fe3+ and H2O2

CDs synthesized from o-phenylenediamine through microwave-assisted method show great potential for Fe³⁺ and H₂O₂ detection as well as cell imaging.

Autocatalytic oxidization of nanosilver and its application to spectral analysis

The stable yellow nanosilver (AgNP) and blue nanosilver (AgNPB) sols were prepared by the NaBH₄ procedure. The new nanocatalytic reaction of AgNP-NaCl-H₂O₂ was investigated by surface plasmon resonance (SPR) absorption, resonance Rayleigh scattering (RRS), surface-enhanced Raman scattering (SERS) and scanning electron microscope (SEM) techniques. The autocatalytic oxidization of Ag on AgNP surface by H₂O₂ was observed firstly and the AgNP/AgCl nanoparticles were characterized. The [Ag⁺] from AgNP is different to the Ag⁺ from AgNO₃ that adsorb on the AgNP surface. An autocatalytic oxidization mechanism was proposed to explain experimental phenomena. The relationship between the SPR absorption peaks and the RRS peaks of AgNPB was studied, and three characteristic RRS peaks called as out-of-plane quadrupole, out-of-plane dipole and in-plane dipole RRS peaks were observed firstly. Using AgNP as nanoprobe, a simple, sensitive and selective RRS method was developed for assay of H₂O₂ in the range of 2.0 × 10⁻⁸-8.0 × 10⁻⁵ mol/L.