Yongtao Li

Nanostructured Molybdenum Oxide Gas Sensors

In this paper, we present a surface acoustic wave (SAW) gas sensor based on nano-structured molybdenum oxide (MoOx) thin film. The film was deposited onto a 36deg YX LiTaO3 SAW transducer, with an operating frequency of approximately 103 MHz, by thermal evaporation. The nanostructured MoOx film consists of connected nanorods with diameters of less than 100 nm. We compared devices with MoOx deposited by RF sputtering and thermal evaporation and found those with evaporated films have response that are an order of magnitude larger.

A Facile Electrochemical Sensor Based on PyTS–CNTs for Simultaneous Determination of Cadmium and Lead Ions

A simple and easy method was implemented for the contemporary detection of cadmium (Cd2+) and lead (Pb2+) ions using 1,3,6,8-pyrenetetrasulfonic acid sodium salt-functionalized carbon nanotubes nanocomposites (PyTS–CNTs). The morphology and composition of the obtained PyTS–CNTs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results confirmed that the fabricated PyTS–CNTs exhibited good selectivity and sensitivity for metal ion-sensing owing to the insertion of sulfonic acid groups. For Cd2+ and Pb2+, some of the electrochemical sensing parameters were evaluated by varying data such as the PyTS–CNT quantity loaded on the pyrolytic graphite electrode (PGE), pH of the acetate buffer, deposition time, and deposition potential. These parameters were optimized with differential pulse anodic sweeping voltammetry (DPASV). Under the optimal condition, the stripping peak current of the PyTS–CNTs/Nafion/PGE varies linearly with the heavy metal ion concentration, ranging from 1.0 μg L−1 to 90 μg L−1 for Cd2+ and from 1.0 μg L−1 to 110 μg L−1 for Pb2+. The limits of detection were estimated to be approximately 0.8 μg L−1 for Cd2+ and 0.02 μg L−1 for Pb2+. The proposed PyTS–CNTs/Nafion/PGE can be used as a rapid, simple, and controllable electrochemical sensor for the determination of toxic Cd2+ and Pb2+.

Selective voltammetric determination of Cd(II) by using N,S-codoped porous carbon nanofibers

AbstractPorous carbon nanofibers codoped with nitrogen and sulfur (NFs) were prepared by pyrolysis of trithiocyanuric acid, silica nanospheres and polyacrylonitrile (PAN) followed by electrospinning. The NFs were used to modify a glassy carbon electrode (GCE) which then displayed highly sensitive response to traces of Cd(II). Compared to a bare GCE and a Nafion modified GCE, the GCE modified with codoped NFs shows improved sensitivity for Cd(II) in differential pulse anodic sweep voltammetry. The stripping peak current (typically measured at 0.81xa0V vs.xa0Ag/AgCl) increases linearly in the 2.0–500xa0μg·L−1 Cd(II) concentration range. This is attributed to the large surface area (109xa0m2·g−1), porous structure, and high fraction of heteroatoms (19xa0at.% of N and 0.75xa0at.% of S). The method was applied to the determination of Cd(II) in (spiked) tap water where it gave recoveries that ranged between 96% and 103%.n Graphical abstractSchematic of a glassy carbon electrode (GCE) modified with N- and S-codoped porous carbon nanofibers (N,S-PCNFs). This GCE has good selectivity for cadmium ion (Cd2+) which can be determined by differential pulse anodic sweeping voltammetry (DPASV) with a detection limit as low as 0.7 ng·mL−1.

A New Non-Enzymatic Amperometric Sensor Based on Nickel Decorated ZIF-8 Derived Carbon Nanoframe for the Glucose Determination in Blood Samples

The present study demonstrated a highly sensitive non-enzymatic glucose biosensor in real blood samples based on simple evaluated nickel deposited on N-doped porous carbon modified glassy carbon el ...

Synthesis of an iron-nitrogen co-doped ordered mesoporous carbon-silicon nanocomposite as an enhanced electrochemical sensor for sensitive and selective determination of chloramphenicol

In this study, we developed a sensitive electrochemical sensor for the detection of chloramphenicol (CAP). An iron-nitrogen co-doped ordered mesoporous carbon-silicon nanocomposite (Si-Fe/NOMC) was prepared as follows. First, an SBA-15 surface was treated with an iron and nitrogen co-doped carbon framework obtained from the polymerization of ethylenediamine and carbon tetrachloride via the hard templating method. The mixture was then carbonized at a high temperature (900℃). Finally, the Si-Fe/NOMC modified electrode was fabricated, and employed as a high-performance electrochemical sensor to trace the CAP in drug samples using the large surface area of the hetero-atoms iron, nitrogen and silicon co-doped in the porous structure. Cyclic voltammetry and differential pulse voltammetry tests were determine to assess the efficiency of the sensor. Under optimized conditions, the sensor exhibited rapid current response for CAP in a phosphate buffer solution PBS with pH 7.5. The linear concentration of CAP ranged from 1 μM to 500 μM, with a limit of detection of 0.03 μM (S/Nu2009=u20093). Furthermore, the electrochemical sensor was used to detect CAP in eye drop samples with satisfactory results.

SAW Hydrogen Sensor with Electropolymerized Polyaniline Nanofibers

In this work a surface acoustic wave (SAW) gas sensor based on a 64deg YX LiNbO3 substrate has been developed. The sensitive layer consists of electropolymerized polyaniline nanofibers. Device was tested towards hydrogen gas

A ZnO Nanorod Based 64° YX LiNbO3 Surface Acoustic Wave CO Sensor

Zinc oxide (ZnO) nanorod based surface acoustic wave (SAW) gas sensor has been developed. ZnO nanorods were deposited onto a layered ZnO/64deg YX LiNbO3 substrate using a liquid solution method. Micro-characterization results reveal that the diameter and area density of ZnO nanorods are around 100 nm and 107 cm-2, respectively. The sensor was exposed to different concentrations of CO in synthetic air. The sensor response at operating temperatures between 200degC and 300degC was examined. The study showed that the sensor responded with highest frequency shift at 265degC. At this temperature, stable base-line and fast response and recovery were observed. The developed sensor is promising for industrial applications.

Study of Ga/sub 2/O/sub 3/ thin film gas sensors

In this paper we present the gas sensing performance of pure, doped and Pt modified Ga/sub 2/O/sub 3/ thin films prepared by the sold-gel process. The oxygen gas sensing performance of the binary compound Ga/sub 2/O/sub 3/ is compared with that of pure Ga/sub 2/O/sub 3/ and ZnO. The Ga/sub 2/O/sub 3/-ZnO binary compound sensor showed preferred gas sensing in the temperature range of 450 to 550/spl deg/C and outperformed the pure Ga/sub 2/O/sub 3/ and ZnO sensors for every oxygen gas concentration tested. Furthermore, the stoichiometry of the semiconducting Ga/sub 2/O/sub 3/ has been confirmed by X-ray photoelectron spectroscopy (XPS). For H/sub 2/ measurements, a 70nm layer of Pt was deposited on top of the Ga/sub 2/O/sub 3/ to enhance the response and a comparison of the device with and without this layer is also presented. It was found that the addition of the Pt layer decreased the H/sub 2/ response and recovery times by over 65%.