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Electrostatic spray deposition was applied to prepare pH sensing with spinel ZnCO2O4 thin films based on the measurement of extended-gate field-effect transistors (EGFET). The influence of annealing temperatures on the characteristics of the prepared films was analyzed. The structural and morphological properties of the annealed ZnCo2O4 films were assessed by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and contact angle measurement. The effect of the ZnCo2O4 annealing temperature on the characteristics of pH sensing for the prepared ZnCo2O4 films in EGFET measurement were examined with pH buffer solutions in a pH range of 2–12 at room temperature. The sensing films annealed at 550°C demonstrated a high voltage and current sensitivity at 67.6 mV/pH and 1.033 (µA)½/pH, with linearity values of 0.9968 and 0.9991, respectively. Moreover, the annealed 550°C ZnCo2O4 film exhibited low hysteresis at 4.99 mV and high retention stability. The results revealed that the pH sensing of the ZnCo2O4 EGFET device showed a super-Nernstian sensitivity, which indicated the influence of the surface properties of the annealed film. Therefore, the ZnCo2O4 film should be considered a potential option for the pH sensing layer in EGFET applications. [ABSTRACT FROM AUTHOR]

Graphene-based materials such as graphene oxide (GO) and chemically reduced graphene oxide (rGO) thin films have been fabricated using electrostatic spray deposition (ESD), followed by thermal annealing under Ar/H2 atmosphere. The thickness and surface morphology of thin films of GO and rGO on silicon substrates were controlled by varying deposition time and content of GO/rGO in tetrahydrofuran (THF) solution. Here, we present a comparative analysis between GO and rGO thin films. Water contact angle (WCA) measurements of these thin films were ~88° for the GO films and >127° for the rGO films. We discuss how their hydrophobic behaviour is influenced by removal of oxygen-containing functional groups during the reduction process. [ABSTRACT FROM AUTHOR]

Thin-film electrodes of graphene nanoplatelets (GNPs) were fabricated through the electrostatic spray deposition (ESD) technique. The combination of a binder-free deposition technique and an open pore structure of graphene films results in an excellent power handling ability of the electrodes. Cyclic voltammetry measurements of 1-μm-thick electrodes yield near rectangular curves even at a very high scan rate of 20 V s. Thin-film electrodes (1 μm thickness) show specific power and energy of about 75.46 kW kg and 2.93 W h kg, respectively, at a 5 V s scan rate. For the thin-film electrode, about 53 % of the initial specific capacitance of electrodes at low scan rates was retained at a high scan rate of 20 V s. Although the thickness of the thin-film electrodes has influence on their rate capability, an electrode with an increased thickness of 6 μm retained about 30 % if its initial capacitance at a very high scan rate of 20 V s. The results show that the ESD-fabricated GNP electrodes are promising candidates for thin-film energy storage for applications that require moderate energy density and very high power and rate handling ability. [ABSTRACT FROM AUTHOR]

3 Mol% of europium doped strontium aluminate (SrAlO:Eu) coatings on silicon substrates were prepared by electrostatic spray deposition method using a salted sol-gel derived solution as a starting material. As-deposited films at 100°C for 5 h were heated at 1100°C for 2 h under a reducing ambient atmosphere of 95%N + 5%H. Nanocrystalline SrAlO film was confirmed by surface morphological and crystallographic analyses. Monitored at 520 nm, the excitation spectrum showed a broad band from 300 ~ 500 nm and the emission intensity showed a maximum yellow peak intensity at 512 nm with a broad band from 460 ~ 610 nm. [ABSTRACT FROM AUTHOR]

In this work, electrostatic deposition was used to prepare porous lanthanum strontium manganite (LSM) films on a silicon substrate for cathode application in solid oxide fuel cells (SOFCs). The precursor solution was prepared by dissolving lanthanum nitrate hydrate, manganese nitrate hexahydrate and strontium chloride hexahydrate into a mixture of methanol and water. The morphology of the LSM film depended on process parameters such as substrate temperature, precursor flow rate, nozzle-substrate distance, and deposition time. The effect of heating temperature on the film’s crystal structure was investigated with X-ray diffraction in the heating temperature range of 700 °C to 900 °C. Porous LSM film was successfully prepared in the solution flow rate range of 2 l/min to 4.5 l/min, substrate temperatures of 127 °C to 330 °C, the nozzle-substrate distance range of 3 cm to 8 cm, and deposition times of 1 min to 16 min. [ABSTRACT FROM AUTHOR]

Electrostatic spray deposition (ESD) was applied to fabricate a thin-layer of yttria-stabilized zirconia (YSZ) electrolyte on a solid oxide fuel cell (SOFC) anode substrate consisting of nickel-YSZ cermet. A colloidal solution of 8 mol% YSZ in ethanol was sprayed onto the substrate anode surface at 250–300 °C by ESD. After sintering the deposited layer at 1250–1400 °C for 1–2 h depending on temperature, the cathode layer, consisting of lanthanum strontium manganate (LSM), was sprayed or brush coated onto the electrolyte layer. Performance tests and AC impedance measurements of the complete cell were carried out at 800 °C to evaluate the density and conductance of the electrolyte layer formed by ESD. With a 97% H2/3% H2O mixture and air as fuel and oxidant gas, respectively, the open-circuit voltage (OCV) was close to theoretical and electrolyte impedance was about 0.23Ω cm2. A power density of 0.45 W cm−2 at 0.62 V was obtained. No abnormal degradation was observed after 170 h operation. The electrolyte sintering temperature and time did not significantly affect the electrolyte impedance. [ABSTRACT FROM AUTHOR]

Electrostatic spray deposition (ESD) was applied to fabricate a thin-layer (~3 µm thickness) yttria-stabilized zirconia (YSZ) electrolyte on a solid oxide fuel cell (SOFC) anode substrate consisting of nickel-YSZ cermet. Reducing the thickness of a state-of-the-art electrolyte, and thereby reducing the cell internal IR drop, is a promising strategy to make the intermediate temperature SOFC (ITSOFC) operating at 600-800 °C possible. About 8 mol% YSZ colloidal solution in ethanol was sprayed onto the substrate anode surface at 250-300 °C by ESD. After sintering the deposited layer at 1250-1400 °C for 17-6 h, the cathode layer, consisting of lanthanum strontium manganate (LSM), was sprayed or brush coated onto the electrolyte layer. Performance tests on the cell were carried out at 800 °C to evaluate the electrolyte layer formed by ESD. With a 97 H2/3 H2O mixture and air as fuel and oxidant gas, respectively, open circuit voltage (OCV) was found to be close to the theoretical value. [ABSTRACT FROM AUTHOR]

The deposition of perovskite-type oxides thin films [LaSrMnO and LaSrCoFeO (0 ≦ x ≦ 0.4 and 0 ≦ y ≦ 1)] was investigated using the electrostatic spray deposition (ESD) technique. Lanthanum nitrate, strontium chloride and manganese nitrate, or cobalt nitrate and iron nitrate were dissolved into a mixture of 33 vol% ethanol and 67 vol% butyl carbitol, which was used as precursor solution. The effect of process parameters, such as deposition temperature, deposition time and concentration of precursor solution, on the surface morphology and microstructure of thin films were examined with scanning electron microscope (SEM). The deposited LaSrMnO and LaSrCoFeO thin films were amorphous at the used deposition temperature (573K). Subsequently, the samples were heated at 1173 K for 2 h and were studied using X-ray diffraction (XRD). As the result, the crystal structure of the samples transformed to the desired perovskite phase. The chemical analysis of the thin films was investigated using energy dispersion X-ray (EDX) analysis. The observed chemical compositions of the samples were in a fair agreement with the ones of the starting solutions. [ABSTRACT FROM AUTHOR]