This research focused on advanced oxidation of toluene by evaluating Ni-olivine catalysts in combination with ozone. Specifically, our objectives were to: (1) synthesize catalysts via electroless plating (ELP) and thermal impregnation (TI) techniques to impregnate nickel onto the olivine surface; (2) characterize Ni-olivine catalysts by Brunauer-Emmett-Teller specific surface area, electron microscopy, energy dispersive spectroscopy, and x-ray photoelectron spectroscopy to understanding the mechanisms of toluene oxidation; (3) determine the catalytic activity of the newly synthesized Ni-olivine catalysts in the oxidation of toluene; and (4) evaluate the influence of varying toluene and ozone concentrations on Ni-olivine oxidation efficiencies. Testing was performed in a continuous packed bed reactor (200 degrees C). Toluene (200 to 600 ppmv) and ozone (70 to 800 ppmv) were injected into the heated reactor, while inlet and outlet concentrations were measured using gas chromatography. Results indicated that 90% of toluene was oxidized within a 1 s residence time using ELP and TI catalyst synthesis techniques and 70 ppmv ozone. Microscopic and spectroscopic analyses revealed porous structures and a nickel film uniformly coating the electroless plated olivine surface, mostly comprised of Ni-P-O, while the thermally impregnated Ni-olivine possessed sparingly deposited Ni2O3 compounds on the surface. An increase in ozone concentrations increased toluene oxidation efficiencies, whereas an increase in toluene concentrations temporarily decreased toluene oxidation efficiencies. Knowledge obtained from this research can be used for synthesizing advanced catalysts for toluene oxidation at significantly lower temperature.

The production of synthesis gas (syngas) involves the gasification of biomass under oxygen-limited conditions, which also produces tars. Tars pose significant problems for mechanical devices by depositing on piping, resulting in clogging and engine fouling. While recent research has shown that thermally impregnated Ni-olivine has been effective in reforming tars into H-2 and CO, this technique possessed limited economic feasibility due to high input energy requirements. Thus, stable, active, and inexpensive catalysts are required for effective and efficient conditioning of syngas. This research compared the activity of Ni-olivine catalysts synthesized via electroless plating (ELF) (35 degrees C) and thermal impregnation (TI) (1400 degrees C) for oxiding toluene in a flow-through reactor The objectives were to (1) determine the kinetics of toluene oxidation, (2) propose a reaction mechanism for toluene oxidation, and (3) investigate the effect of syngas on toluene oxidation. Conversion of toluene using Ni-olivine catalysts increased with increasing ozone concentration and temperature, as well as decreasing toluene molar flow rate, and facilitated the complete oxidation of toluene. The information obtained from this research is expected to provide opportunities for efficient cleanup of tars from biomass gasification facilities at lower temperatures.

In this work, we enhanced the performance of a fluidic glucose sensor by using three dimensional electrodes made of standing nanopillars. To fabricate the electrodes, vertically standing gold nanopillars on gold films deposited on glass substrates were first formed. The nanopillars along with the underlying film were then patterned into electrodes (in a three-electrode design) and the electrodes were then enclosed in a PDMS chamber to form a fluidic sensor device. Of the three electrodes, one was used as enzyme electrode after functionalization with an enzyme (i.e. glucose oxidase) and the other two were used as working and counter electrodes, respectively. The performance of this fluidic glucose sensor was evaluated by measuring amperometric currents at various glucose concentrations. The nanopillar modified glucose sensor exhibited linear behavior with a sensitivity value as high as 35.9μAcm−2mM−1 in a concentration range from 0.25 to 2.5mM. In comparison with a fluidic glucose sensor having only flat electrodes, the detection sensitivity for the sensor with nanopillar modified electrodes was five times higher.

In this report, alkanethiol self assembled monolayers (SAM) with two different chain lengths were used to immobilize the functionalizing enzyme (glucose oxidase) onto gold nanopillar modified electrodes and the electrochemical processes of these functionalized electrodes in glucose detection were investigated. First, the formation of these SAMs on the nanopillar modified electrodes was characterized by the cyclic voltammetry and electrochemical impedance spectroscopy techniques, and then the detection sensitivity of these functionalized electrodes to glucose was evaluated by the amperometry technique. Results showed that the SAM of alkanethiols with a longer chain length resulted in a higher degree of surface coverage with less defect and a higher electron transfer resistance, whereas the SAM of alkanethiols with a shorter chain length gave rise to a higher detection sensitivity to glucose. This study sheds some new insight into how to enhance the sensing performance of nanopillar modified electrodes.

In this study, the functionalization process for nanopillar enhanced electrodes (NEEs) using glucose oxidase (GOx) with polypyrrole (PPY) is optimized for the purpose of achieving enhanced sensing performances for these electrodes in glucose detection. Specifically, an optimal roughness factor for the NEEs and an optimal set of electro-polymerization/deposition parameters for their functionalization using GOx/PPY are identified. Results show that NEEs with a roughness factor of about 60 are optimal for enhancing the amperometric current responses and that for such electrodes an electro-functionalization/deposition process at a deposition current of 50 µA cm−2 and a total charge of 150 mC cm−2 will give rise to a high sensing performance with a sensitivity as high as 36 µA cm−2 mM−1.