The Experts below are selected from a list of 47946 Experts worldwide ranked by ideXlab platform
Anastasios Economou - One of the best experts on this subject based on the ideXlab platform.
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3d printed lab in a syringe voltammetric cell based on a Working Electrode modified with a highly efficient ca mof sorbent for the determination of hg ii
Sensors and Actuators B-chemical, 2020Co-Authors: Christos Kokkinos, Anastasios Economou, Anastasia Pournara, Manolis J Manos, Ioannis Spanopoulos, Mercouri G Kanatzidis, Thomais G Tziotzi, Valeri Petkov, Antigoni Margariti, Panagiotis OikonomopoulosAbstract:Abstract This work combines, for the first time, 3D-printing technology and a highly efficient metal organic framework (Ca-MOF) as an Electrode modifier to produce a novel fully integrated lab-in-a-syringe device for the sensitive determination of Hg(II) by anodic stripping voltammetry. The specific Ca-MOF ([Ca(H4L)(DMA)2]·2DMA where H6L is the N,N’-bis(2,4-dicarboxyphenyl)-oxalamide and DMA is the N,N-dimethylacetamide) shows an exceptional Hg(II) sorption capability over a wide pH range and its mechanism is elucidated via spectroscopic and X-ray diffraction studies. The voltammetric lab-in-a-syringe device is fabricated through a single-step process using a dual extruder 3D printer and is composed of a vessel integrating two thermoplastic conductive Electrodes (serving as the counter and pseudo-reference Electrodes) and of a small detachable 3D-printed syringe loaded with a graphite paste/Ca-MOF mixture (which serves as the Working Electrode). After optimization of the fabrication and operational variables, a limit of detection of 0.6 μg L−1 Hg(II) was achieved, which is comparable or lower than that of existing sensors (plastic 3D-printed, gold and MOF-based Electrodes). The adoption of 3D printing technology in combination with the highly efficient Ca-MOF enables the fabrication of a simple, low-cost and sensitive electrochemical sensor for Hg(II), which is suitable for on-site applications.
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disposable microfabricated 3 Electrode electrochemical devices with integrated antimony Working Electrode for stripping voltammetric determination of selected trace metals
Sensors and Actuators B-chemical, 2014Co-Authors: Christos Kokkinos, Anastasios EconomouAbstract:Abstract This work reports the fabrication of novel 3-Electrode integrated devices featuring an Sb-film Working Electrode and Ag and Pt planar strips serving as the reference and counter Electrodes, respectively. The deposition of the metal layers was carried out by sputtering of the respective metals on an oxidized silicon substrate, while the Electrodes were patterned via a metal mask and isolated using a simple photolithographic step. The utility of these devices was tested for the simultaneous trace determination of Pb(II) and Tl(I) by square-wave anodic stripping voltammetry (SWASV) in strong acidic medium (0.05 mol L −1 phosphoric acid) in which the antimony sensor exhibited advantageous electroanalytical performance. The limits of detection were 0.7 μg L −1 for Pb(II) and 0.9 μg L −1 for Tl(I), and the within-sensor reproducibility was 3.2% for Pb(II) and 3.9% for Tl(I) at the 20 μg L −1 level ( n = 12). The applicability of these novel sensors was demonstrated for the analysis of a spiked mineral water sample.
Christos Kokkinos - One of the best experts on this subject based on the ideXlab platform.
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3d printed lab in a syringe voltammetric cell based on a Working Electrode modified with a highly efficient ca mof sorbent for the determination of hg ii
Sensors and Actuators B-chemical, 2020Co-Authors: Christos Kokkinos, Anastasios Economou, Anastasia Pournara, Manolis J Manos, Ioannis Spanopoulos, Mercouri G Kanatzidis, Thomais G Tziotzi, Valeri Petkov, Antigoni Margariti, Panagiotis OikonomopoulosAbstract:Abstract This work combines, for the first time, 3D-printing technology and a highly efficient metal organic framework (Ca-MOF) as an Electrode modifier to produce a novel fully integrated lab-in-a-syringe device for the sensitive determination of Hg(II) by anodic stripping voltammetry. The specific Ca-MOF ([Ca(H4L)(DMA)2]·2DMA where H6L is the N,N’-bis(2,4-dicarboxyphenyl)-oxalamide and DMA is the N,N-dimethylacetamide) shows an exceptional Hg(II) sorption capability over a wide pH range and its mechanism is elucidated via spectroscopic and X-ray diffraction studies. The voltammetric lab-in-a-syringe device is fabricated through a single-step process using a dual extruder 3D printer and is composed of a vessel integrating two thermoplastic conductive Electrodes (serving as the counter and pseudo-reference Electrodes) and of a small detachable 3D-printed syringe loaded with a graphite paste/Ca-MOF mixture (which serves as the Working Electrode). After optimization of the fabrication and operational variables, a limit of detection of 0.6 μg L−1 Hg(II) was achieved, which is comparable or lower than that of existing sensors (plastic 3D-printed, gold and MOF-based Electrodes). The adoption of 3D printing technology in combination with the highly efficient Ca-MOF enables the fabrication of a simple, low-cost and sensitive electrochemical sensor for Hg(II), which is suitable for on-site applications.
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disposable microfabricated 3 Electrode electrochemical devices with integrated antimony Working Electrode for stripping voltammetric determination of selected trace metals
Sensors and Actuators B-chemical, 2014Co-Authors: Christos Kokkinos, Anastasios EconomouAbstract:Abstract This work reports the fabrication of novel 3-Electrode integrated devices featuring an Sb-film Working Electrode and Ag and Pt planar strips serving as the reference and counter Electrodes, respectively. The deposition of the metal layers was carried out by sputtering of the respective metals on an oxidized silicon substrate, while the Electrodes were patterned via a metal mask and isolated using a simple photolithographic step. The utility of these devices was tested for the simultaneous trace determination of Pb(II) and Tl(I) by square-wave anodic stripping voltammetry (SWASV) in strong acidic medium (0.05 mol L −1 phosphoric acid) in which the antimony sensor exhibited advantageous electroanalytical performance. The limits of detection were 0.7 μg L −1 for Pb(II) and 0.9 μg L −1 for Tl(I), and the within-sensor reproducibility was 3.2% for Pb(II) and 3.9% for Tl(I) at the 20 μg L −1 level ( n = 12). The applicability of these novel sensors was demonstrated for the analysis of a spiked mineral water sample.
Nasser A M Barakat - One of the best experts on this subject based on the ideXlab platform.
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cd doped tio2 nanofibers as effective Working Electrode for the dye sensitized solar cells
Materials Letters, 2019Co-Authors: Moaaed Motlak, A M Hamza, Mohammed Gh Hammed, Nasser A M BarakatAbstract:Abstract Cd-doping and nanofibrous morphology are proposed to improve the TiO2 performance as photoanode in the dye-sensitized solar cells. Practical results indicate that Cd ions interfered with the crystalline structure of TiO2 nanofibers, causing an increase in the absorption in the visible spectrum, transport of the charges, and reduced re-bonding between the charge carriers in the barrier area between the electrolyte and the Working Electrode, compared to the un-doped titania nanofibers. It is interesting that a DSSC based on a Cd-doped TiO2 nanofiber Working Electrode has a double power conversion efficiency (2.945%) compared with the pristine titanium oxide nanofibers-based cell; 1.54%.
Shannon W. Boettcher - One of the best experts on this subject based on the ideXlab platform.
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junction behavior of n si photoanodes protected by thin ni elucidated from dual Working Electrode photoelectrochemistry
Energy and Environmental Science, 2017Co-Authors: Forrest A L Laskowski, Michael R Nellist, Radhakrishnan Venkatkarthick, Shannon W. BoettcherAbstract:Si is a desirable photoanode material for use in photoelectrochemical water-splitting devices. However, Si self-passivates during the oxygen evolution half reaction and requires a protection layer to maintain high photoanodic efficiency. Thin evaporated metallic Ni layers have been reported to protect Si while also enhancing the kinetics for oxygen evolution. Maximizing performance of these and related protected/catalyzed semiconductors requires a fundamental understanding of the semiconductor|catalyst|solution interface. We use dual-Working-Electrode (DWE) photoelectrochemistry measurements to directly measure the interface's electronic properties in situ during operation. By controlling the Ni thickness (3, 5, and 20 nm), we confirm that favorable shifts in photocurrent onset are correlated with thinner protection layers. Photoelectrochemical DWE measurements are used to test various prevailing hypotheses for the origin of this behavior. We find evidence that increased photovoltage is due to the development of a spatially inhomogeneous buried junction wherein high barrier regions arise via adventitious SiO2 growth. Thinner protection layers more readily promote this behavior by facilitating solution permeation to the n-Si|Ni interface. Repeated electrochemical cycling of thicker catalyst layers can achieve similar behavior and improve the photocurrent onset by as much as 300 mV. The results are discussed in the context of the general design principles for metal–insulator–semiconductor protected photoanodes.
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Advanced Photoelectrochemical Characterization: Principles and Applications of Dual-Working-Electrode Photoelectrochemistry
Photoelectrochemical Solar Fuel Production, 2016Co-Authors: Shannon W. BoettcherAbstract:The performance of a photoElectrode for photoelectrochemical solar fuel production can be enhanced by integrating an overlayer of electrocatalyst (EC) with the light-absorbing semiconductor (SC). However, the mechanisms through which the EC overlayer improves performance of composite photoElectrodes are not well understood. While the simple view is that the addition of the EC increases reaction kinetics, real systems are more complicated due to the existence of multiple, interacting components. Knowledge about the dynamic state of each critical component in complex photoelectrochemical (PEC) systems such as catalyzed photoElectrodes (and, e.g., dye-sensitized solar cells) could provide important insights. This information, however, is typically not directly accessible through a conventional three-Electrode PEC cell setup with a single-Working Electrode (SWE) connected to the SC, a counter Electrode, and a reference Electrode. In this chapter we discuss the “dual-Working-Electrode” (DWE) PEC experimental technique that features an additional Working Electrode, which could be used to directly monitor or control the state of crucial components, such as the EC layer of a composite photoElectrode. We illustrate how this DWE PEC technique was employed to directly measure the in situ properties of SC|EC junctions in model water-oxidizing photoanodes and thus help answer the question of how the EC layer improves the PEC performance of composite photoElectrodes. We further discuss directions for future efforts in this area.
Dachao Li - One of the best experts on this subject based on the ideXlab platform.
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a flexible enzyme Electrode sensor with cylindrical Working Electrode modified with a 3d nanostructure for implantable continuous glucose monitoring
Lab on a Chip, 2018Co-Authors: Zhihua Pu, Jianwei Wu, Haixia Yu, Jiaan Tu, Xingguo Zhang, Chao Fang, Hao Wu, Xiaoli Zhang, Dachao LiAbstract:A novel cylindrical flexible enzyme-Electrode sensor was fabricated with a bigger Working Electrode (WE) surface than the traditional pin-like one for implantable continuous glucose monitoring. On the WE surface, a 3D nanostructure consisting of graphene and platinum nanoparticles was constructed to enhance the sensitivity; in conjunction with the bigger WE, this nanostructure enabled hypoglycemia detection, which is still a big challenge in clinics. The cylindrical sensor was fabricated by rotated inkjet printing which enabled direct patterning of microstructures on a curved surface, thus overcoming the restriction of the traditional planar micromachining by photolithography. Specifically, the cylindrical substrate (polyetheretherketone, PEEK) was modified by (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane to facilitate surface wettability, which discourages the coalescence of adjacent droplets, and to facilitate the adhesion of metals to PEEK in order to construct robust Electrodes. A synchronous heating method was used to evaporate the solvent of the droplets quickly to prevent them from running along the cylindrical surface, which affects the formation of the printed Electrode significantly. In vitro experimental results showed that the proposed sensor was able to detect the glucose concentration ranging from 0 to 570 mg dL−1 which demonstrated its capability for physiological glucose detection. In vivo experiments were conducted with rats, and the measurement results recorded using the implanted cylindrical sensor showed great compliance to those recorded using a commercial glucometer which exhibited the viability of the proposed sensor for implantable continuous glucose monitoring, even under the hypoglycemic conditions.
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a flexible electrochemical glucose sensor with composite nanostructured surface of the Working Electrode
Sensors and Actuators B-chemical, 2016Co-Authors: Zhihua Pu, Ridong Wang, Jianwei Wu, Haixia Yu, Kexin Xu, Dachao LiAbstract:Abstract Detecting hypoglycemia remains a great challenge with regard to continuous glucose monitoring in clinical settings. This paper investigates a novel, flexible three-Electrode electrochemical sensor with a composite nanostructured Working Electrode surface that has been modified by graphene and gold nanoparticles in order to detect low levels of glucose with high accuracy. The sensor Electrodes were fabricated on a polyimide substrate using the flexible printed circuit board (PCB) method. Graphene was modified directly onto the Working Electrode surface via inkjet printing, an emerging method for micro-scale fabrications, to enable glucose detection at low levels. Gold nanoparticles were Electrodeposited directly onto the graphene layer to enhance the sensitivity of the sensor. The experimental results demonstrate that the proposed sensor can precisely measure glucose with a linear range of 0–40 mg/dL and a detection limit of 0.3 mg/dL (S/N = 3), thereby demonstrating potential for hypoglycemia detection. Moreover, this flexible sensor was suitable for integration within a microfluidic chip, which could be used to transdermally extract and collect ISF, such that a wearable device could be developed for continuous glucose monitoring.
