Hongjie Song

Graphene sheets decorated with SnO2 nanoparticles: in situ synthesis and highly efficient materials for cataluminescence gas sensors

Graphene sheets decorated with SnO2 nanoparticles were prepared through a facile hydrothermal-assisted in situ synthesis route. According to the XPS, XRD, FESEM and TEM analysis, rutile SnO2 nanocrystals were exclusively deposited on graphene sheets with high density and high uniformity to form layered composite sheets. Propanal, a common volatile organic compound, was selected as a model to investigate the cataluminescence (CTL) sensing properties of the SnO2/graphene composite in this paper. It was found that the strong CTL emission could be generated due to the catalyzing oxidization of propanal on the surface of SnO2/graphene composite and this composite was an efficient sensing material for propanal. We further studied the analytical characteristics of the CTL sensor based on SnO2/graphene composite sensing material for propanal under the optimal experimental conditions. The linear range of the propanal gas sensor was 1.34–266.67 μg mL−1 (r = 0.9987), over two orders of magnitude, and the detection limit was 0.3 μg mL−1(S/N = 3).

SiO2/graphene composite for highly selective adsorption of Pb(II) ion

SiO(2)/graphene composite was prepared through a simple two-step reaction, including the preparation of SiO(2)/graphene oxide and the reduction of graphene oxide (GO). The composite was characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray photoelectron spectroscopy, and what is more, the adsorption behavior of as-synthesized SiO(2)/graphene composite was investigated. It was interestingly found that the composite shows high efficiency and high selectivity toward Pb(II) ion. The maximum adsorption capacity of SiO(2)/graphene composite for Pb(II) ion was found to be 113.6 mg g(-1), which was much higher than that of bare SiO(2) nanoparticles. The results indicated that SiO(2)/graphene composite with high adsorption efficiency and fast adsorption equilibrium can be used as a practical adsorbent for Pb(II) ion.

Well-redispersed ceria nanoparticles: Promising peroxidase mimetics for H2O2 and glucose detection

Well-redispersed ceria nanoparticles (CeO2 NPs) were synthesized by a simple hydrothermal method. The prepared CeO2 NPs exhibited excellent catalytic activity towards classical peroxidase substrate 3,3,5,5-tetramethylbiphenyl dihydrochloride (TMB·2HCl) in the presence of H2O2, based on which a colorimetric method that is highly sensitive and selective was developed for glucose detection. The composition, structure, morphology and peroxidase-like catalytic activity of CeO2 NPs are investigated in detail by using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), thermal analysis (TG) and UV-vis absorption spectroscopy. According to this method, the detection of H2O2 and glucose are in linear range from 6.0 × 10−7 to 1.5 × 10−6 mol L−1 and 6.6 × 10−6 to 1.3 × 10−4 mol L−1, with the detection limit down to 5.0 × 10−7 mol L−1 H2O2 and 3.0 × 10−6 mol L−1 glucose, respectively. Further, this simple, cheap, highly sensitive and selective colorimetric method for glucose detection was successfully applied for the determination of glucose in human serum samples.

Luminescent ZnO quantum dots for sensitive and selective detection of dopamine

Water-soluble and luminescent ZnO quantum dots (QDs) capped by (3-aminopropyl) triethoxysilane (APTES) are environment-friendly with strong photoluminescence (max. wavelength: 530 nm). Interestingly, it was found that the fluorescence could be quenched by dopamine (DA) directly. On the basis of above, a novel ZnO QDs based fluorescent probe has been successfully designed to detect DA with high selectivity and sensitivity. Moreover, the possible fluorescence quenching mechanism was proposed, which showed that the quenching effect may be caused by the electron transfer from ZnO QDs to oxidized dopamine-quinone. Under optimum conditions, the relative fluorescence intensity was linearly proportional to the concentration of DA within the range from 0.05 to 10 μM, with the detection limit down to 12 nM (n=3). Also, the selectivity experiment indicated the probe had a high selectivity for DA over a number of possible interfering species. Finally, this method was successfully used to detect DA in serum samples with quantitative recoveries (99-110%). With excellent selectivity and high sensitivity, it is believed that the ZnO QDs based fluorescent probe has a potential for the practical application in clinical analysis.

Sonochemical synthesis of Ag nanoclusters: electrogenerated chemiluminescence determination of dopamine.

We report a facile one-pot sonochemical approach to preparing highly water-soluble Ag nanoclusters (NCs) using bovine serum albumin as a stabilizing agent and reducing agent in aqueous solution. Intensive electrogenerated chemiluminescence (ECL) was observed from the as-prepared Ag (NCs) and successfully applied for the ECL detection of dopamine with high sensitivity and a wide detection range. A possible ECL mechanism is proposed for the preparation of Ag NCs. With this method, the dopamine concentration was determined in the range of 8.3 × 10(-9) to 8.3 × 10(-7) mol/L without the obvious interference of uric acid, ascorbic acid and some other neurotransmitters, such as serotonin, epinephrine and norepinephrine, and the detection limit was 9.2 × 10(-10) mol/L at a signal/noise ratio of 3.

Hierarchical SnO2 architectures: controllable growth on graphene by atmospheric pressure chemical vapour deposition and application in cataluminescence gas sensor

A facile catalyst-free atmospheric pressure chemical vapour deposition (APCVD) method for the growth of hierarchical SnO2 architectures on graphene is demonstrated. SnO2 2D nanorod arrays, flower@column composites, dendrite structures, and nanoparticles grown on graphene, named as SnO2/graphene architectures, were synthesized on Thermally-Reduced Graphene Oxide (TRGO) and Chemically-Reduced Graphene Oxide (CRGO), respectively. According to characterizations, the rutile SnO2 architectures had large-area uniformity and high crystallinity, which were highly densely and uniformly grown on graphene. A self-catalyzed vapor–solid (VS) and a self-catalyzed vapor–liquid–solid (VLS) mechanisms were proposed based on the detailed observation on the growth behaviour of the SnO2/graphene materials. The synthesized SnO2/graphene materials were directly used to construct gas sensors for methanol detection based on the cataluminescence (CTL) emission. Further study indicated that the SnO2/graphene materials showed enhanced CTL response to methanol and a morphology-dependent CTL performance. And then a fast and highly effective gas sensor for selective detection of methanol was designed based on the SnO2/graphene nanoparticles. The linear range of the methanol gas sensor was 6.3–88.5 μg mL−1, and the detection limit was 5.2 μg mL−1 (S/N = 3).

Graphene‐amplified electrogenerated chemiluminescence of CdTe quantum dots for H2O2 sensing

Electrogenerated chemiluminescence (ECL) of thiol-capped CdTe quantum dots (QDs) in aqueous solution was greatly enhanced by PDDA-protected graphene (P-GR) film that were used for the sensitive detection of H2 O2 . When the potential was cycled between 0 and -2.3 V, two ECL peaks were observed at -1.1 (ECL-1) and -1.4 V (ECL-2) in pH 11.0, 0.1 M phosphate buffer solution (PBS), respectively. The electron-transfer reaction between individual electrochemically-reduced CdTe nanocrystal species and oxidant coreactants (H2 O2 or reduced dissolved oxygen) led to the production of ECL-1. While mass nanocrystals packed densely in the film were reduced electrochemically, assembly of reduced nanocrystal species reacted with coreactants to produce an ECL-2 signal. ECL-1 showed higher sensitivity for the detection of H2 O2 concentrations than that of ECL-2. Further, P-GR film not only enhanced ECL intensity of CdTe QDs but also decreased its onset potential. Thus, a novel CdTe QDs ECL sensor was developed for sensing H2O2. Light intensity was linearly proportional to the concentration of H2 O2 between 1.0 × 10(-5) and 2.0 x 10(-7) mol L(-1) with a detection limit of 9.8 x 10(-8) mol L(-1). The P-GR thin-film modified glassy carbon electrode (GCE) displayed acceptable reproducibility and long-term stability.

Accelerated reducing synthesis of Ag@CDs composite and simultaneous determination of glucose during the synthetic process

Carbonaceous nanodots (CDs) have drawn increasing attention owing to their inspiring properties. CDs based composites have been attracting extensive research interest because of the properties improvement of materials and introduction of new physical or chemical properties. In this work, we designed a quick, handy and extra-reductant needless method to synthesize Ag@CDs composites according to the direct reduction of Ag(NH3)2OH. TEM, XPS, XRD and optical properties were investigated, and a hypothetical synthesis mechanism was provided. Interestingly, glucose lowered the reaction difficulty and shortened the reaction time, which was well known as silver mirror reaction. Furthermore, a dual signal sensor for glucose was established through optical variations during the synthetic process. The simultaneous synthesis and detection avoided complicated pre-modification of the materials and thus simplified the procedure. The synthesis by a simple elementary reaction and “detection during the synthesis” would attract much interest.

Fabrication of fluorescent nitrogen-rich graphene quantum dots by tin(IV) catalytic carbonization of ethanolamine

A novel metal catalytic strategy, arising from the coordinated interaction between metal ions tin(IV) and ethanolamine, was presented to prepare nitrogen-rich graphene quantum dots (N-rich GQDs) with excellent luminescence properties. In contrast to previous GQDs produced by the bottom-up route, which usually involves complex and harsh synthetic procedures, we obtained N-rich GQDs using a single reactant source under mild reaction conditions. Moreover, the prepared N-rich GQDs have shown promising applications as a fluorescence probe toward folic acid.

Recent Advances in Graphitic Carbon Nitride-Based Chemiluminescence, Cataluminescence and Electrochemiluminescence

Graphitic carbon nitride (g-C3N4) has attracted considerable attention due to its special structure and properties, such as its good chemical and thermal stability under ambient conditions, low cost and non-toxicity, and facile synthesis. Recently, g-C3N4-based sensors have been demonstrated to be of high interests in the areas of sensing due to the unique optical, electronic and catalytic properties of g-C3N4. This review focuses on the most salient advances in luminescent sensors based on g-C3N4, chemiluminescence, cataluminescence and electrochemiluminescence methods are discussed. This review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing two-dimensional (2D) nanomaterial-assisted luminescent sensors.