Yu-Ching Weng

Electrodeposited Nickel-Boron Thin-Film Ethanol Sensor

Electrodeposited nickel-boron-based ethanol sensor was constructed by thin-film technique. The sensing layers of nickel-boron films were prepared at constant cathodic current density of 1.5 mA cm -2 in 0.91 M Ni 2 SO 4 , 0.19 M NiCl 2 , and 0.49 M H 3 BO 3 aqueous solution. Amperometric response of this miniaturized sensor was higher than that of the traditional bulky electrodes. The microfabricated electrodeposited nickel-boron electrode exhibits good electrochemical performance in terms of response time [t(90%) = 9 s], linearity (100-600 ppm, r2 = 0.998), and sensitivity (6.1 μA ppm -1 cm -2 ). This sensor also shows a high selectivity to ethanol over malic, citric, ascorbic, and acetic acids. The optimal operating conditions of these ethanol sensors were 80°C of electrodeposition temperature and 20 min of electrodeposition time.

Effects of Electrochemical Deposition of α ­ Ni ( OH ) 2 / Pt / Ti Electrodes for Ethanol Anodic Oxidation

The aim of this paper is to understand the factors involved in the ethanol oxidation of α-Ni(OH) 2 /Pt/Ti electrodes. α-Ni(OH) 2 films are formed on Pt in nickel nitrate solution by cathodic deposition. Both electrode deposition time and nickel nitrate concentration for preparing the working electrode affect the response current of ethanol oxidation. The results showed that oxidation of ethanol significantly depended on the thickness and porosity of α-Ni(OH) 2 . A 0.96 μm thick α-Ni(OH) 2 film could oxidize ethanol effectively. If the a-Ni(OH) 2 film was thicker than 5.09 μm. there was no response current of ethanol oxidation. The optimal operating conditions for preparing a desired thickness of α-Ni(OH) 2 /Pt/Ti electrode were 15 min at I mA cm -2 current density and I M Ni 2+ .

Templateless Nanofiber Photoelectrode Prepared Using Mild Hydrothermal Conditions

The templateless synthesis of titania nanofibers on a Ti foil using a simple and mild approach has been demonstrated. The growth of TiO 2 nanofibers with a diameter of 15 nm on a Ti foil was obtained when Ti foil was hydrothermally treated at 30-95°C in the presence of TiO 2 powder in 0.1-10 M NaOH solutions. Scanning electron microscopy (SEM) observations revealed that TiO 2 seeds clearly appeared on the TiO 2 foil within 20 s and that fiber-shaped films were formed in less than 90 s. A potential formation mechanism for the titania nanofibers on Ti foil is proposed in terms of SEM observations. After the seeds were formed on the Ti foil, the end-on attachments of the nanoparticles resulted in the linear growth of fiberlike structures, upon which nanoparticles were then self-organized to form solid nanofibers. By calcining at a temperature of 550°C, the TiO 2 nanofiber films exhibited optimal photocatalytic activity due to a fine nanofiber structure and good crystallinity of the anatase-rutile mixed phase. The photocatalytic and photoelectrocatalytic activities of the TiO 2 nanofiber electrodes were also assessed with respect to their ability to degrade methyl orange.

Synthesis, crystal structure, optical and electrochemical properties of 9,10-dihydroxybenzo[h]quinoline

Abstract9,10-Dihydroxybenzo[h]quinoline (1), a 10-hydroxybenzo[h]quinoline (2) derivative, was synthesized and characterized by 1H NMR, 13C NMR, UV–vis and fluorescence spectra, and single-crystal X-ray diffraction. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer (ESIPT) takes place from the phenolic proton to the pyridinic nitrogen, resulting in a proton-transfer tautomer emission of 650 nm in dichloromethane. Its molecular geometry in the ground state has also been calculated using density functional theory (DFT) at the B3LYP/6-31G** level and compared with its crystal structure. Results show that the optimized geometry can well reproduce the crystal structure. Furthermore, both absorption and emission spectra of 1 and 2 were calculated using time-dependent DFT (TD-DFT) calculations, and were in good agreement with the experimental results. Graphical AbstractA 10-Hydroxybenzo[h]quinoline derivative, namely, 9,10-dihydroxybenzo[h]quinoline (1) was synthesized and fully characterized. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which ESIPT takes place, resulting in a proton-transfer tautomer emission of ~650 nm in aprotic solvents.

Screening and characterization for the optimization of CdS-based photocatalysts

Scanning electrochemical microscopy (SECM) with an optical fiber was used to rapidly screen M–CdS (M = Cu, Fe, Zn, Co, Ni, Mn and In) photocatalyst arrays for efficient photoelectrochemical reaction. Among the discussed arrays, the spot with the precursor composition In0.2–Cd0.8S showed the highest photocurrent in 0.1 M Na2SO4/Na2SO3 solution under both UV-visible and visible light irradiation. The SECM screening results were also confirmed with bulk photoelectrode studies. The In0.2–Cd0.8S photocatalyst had the hexagonal phase of the wurtzite solid solution structure with an average crystallite size in the range of 13–37 nm. A red shift was observed in the UV-visible absorption spectrum of CdS upon the addition of In. The Mott–Schottky plots showed that the In0.2–Cd0.8S photoelectrode exhibited a flat band potential of −1.2 V vs. Ag/AgCl. The IPCE value at 450 nm radiation for the In0.2–Cd0.8S photocatalyst is 60%, which is three times higher than that of CdS. The superior photocatalytic activity of the In0.2–Cd0.8S photoelectrode is mainly attributed to its high crystallinity, which promotes separation of the photo-induced electrons and holes and also reduces the probability of recombination.

A novel potentiometric sensor based on urease/ bovine serum albumin-poly(3,4-ethylenedioxythiophene)/Pt for urea detection

Abstract We have presented a potentiometric urea sensor using an urease/bovine serum albumin (BSA)-poly(3,4-ethylenedioxythiophene)(PEDOT)/Pt electrode. A urea detection sensitivity of 15.2 mV/decade (order of magnitude) has been achieved. BSA trapped in the PEDOT matrix was employed to bond urease molecules on the surface of a BSA-PEDOT/Pt electrode via amide bonds formed between the carboxyl functional groups on the enzyme and the amines on the BSA. The effects of PEDOT thickness, pH value of the urea solution, urease concentration, and temperature on the urea detection sensitivity were also studied. The lifetime of the sensor was studied for a period of 10 weeks, and the average sensing degradation rate was about 9 % per week. This sensor displayed a high selectivity to urea over glucose, KCl, and NaCl.

Electrochemical Behavior of Cu2+-Histidine Complexes on a Glassy Carbon Electrode

The electrochemical behavior of Cu2+-L-histidine complexes on a glassy carbon electrode with various coordination environments in aqueous solution has been investigated. The Cu2+-histidine complexes are more easily reduced and oxidized at low pH (pH = 3 ~ 4) than at high pH (pH = 8 ~ 10). Both reduction and oxidation reactions of the Cu2+-histidine complexes are controlled by mass transfer at medium (pH = 5 ~ 7) and high pH (pH = 8 ~ 10) solutions. Even if the molar ratio of histidine to Cu2+ ions is as high as 100 : 1 at low pH of 4, the complexes are easily reduced to form Cu metal directly on the electrode surface. Glassy carbon rotating disk electrode experiments have shown that the electron transfer of the reduction reaction of the Cu2+-histidine complexes is close to 2. Graphical Abstract Electrochemical Behavior of Cu2+-Histidine Complexes on a Glassy Carbon Electrode

Effect of the Analytic Regions on the Quality Trend of Diamond-like/Graphitic Carbon Ratios in Raman Spectra

Raman spectroscopy is a useful and non-destructive tool for the structural characterization of diamond-like carbon (DLC) films. Even though Raman spectroscopy is not a quantitative technique, the area integral intensity ratio of D and G peaks (ID/IG) derived by the fitting of separate Gaussian curves usually serves as an indicator of the quality trend of diamond-like material. However, conflicting reports still exist on the diamond-like films analyzed by the fitting method of Raman spectra. In this work we show that the quality trend of the diamond-like/graphitic carbon ratio is critically dependent upon the boundary conditions of the analytic regions. We also examine the possibility of directly applying the peak height ratio HD/HG as an alternative method to analyze Raman spectra. The method based on peak height ratios (HD/HG), and an established method using ID/IG ratios can give similar results depending on the choice, in the latter method, of the boundary conditions used for integration. However, the method based on the determination of peak heights avoids the arbitrary assignment of integral boundary conditions while additionally generating a data set that shows statistically smaller standard deviations than the commonly used integration method Graphical Abstract Effect of the Analytic Regions on the Quality Trend of Diamond-like/Graphitic Carbon Ratios in Raman Spectra

An amperometric acetone sensor by using an electro-deposited Pb-modified electrode

An amperometric acetone sensor was developed by using an electrodeposited Pb electrode in a sodium tartrate electrolyte. The major factors determining the electrode and sensing characteristics such as the applied potential, electrodeposition current density, electrodeposition temperature, agitation rate, and sensing temperature were explored. The best conditions for preparation of the electrodeposited Pb electrode were obtained at a 30 mA cm−2 electrodeposition current density and a 30 °C electrodeposition temperature. Additionally, the optimal sensing conditions are a 155 rpm agitation rate and 50 °C sensing temperature with the applied potential in the range from −2.25 ~−2.35 V (vs. Ag/AgCl). The results also revealed that the electrodeposited Pb electrode has a good linearity between the response current and the acetone concentration. This type of acetone sensor has excellent selectivity and shows the highest sensitivity at 8 μAppm−1cm−2.