Papers by Keyword: PEC

Abstract: Photoelectrochemical cell (PEC) has the same working principle as solar cell which convert solar energy into electricity. PEC consists of photoanode, electrolyte, and counter electrode, where electrolyte plays an important role in determining PEC performance. Yttria-stabilized zirconia (YSZ) is the most suitable electrolyte used due to its high ionic conductivity and chemically stable. In this study, YSZ was deposited to ZnO Nanorods (NRs) by doctor blade method with thickness variation of 100 μm (PEC10) and 120 μm (PEC12). X-ray diffraction (XRD), scanning electron microscope (SEM), and UV-Vis spectroscopy were used to distinguish the phase, morphology, and band gap of the formed materials, respectively. Moreover, I-V test was also conducted to evaluate the performance of the fabricated PEC with different YSZ thickness. SEM image confirmed the deposition thickness of YSZ layer on NRs which formed rough and irregular interface due to grain boundary fusion of YSZ and NRs. In addition, there is little difference XRD pattern from PEC10 and PEC12 which shows ZnO and YSZ peaks with peak shifting observed. Meanwhile, slightly difference noticed on band gap value where PEC10 has 3.25 eV and PEC12 has 3.58 eV. Even though, the characteristic of PEC10 and PEC12 is similar, the I-V test shown a significant difference of solar efficiency where PEC10 has higher efficiency of about 0.328% than PEC12. This difference is contributed by smaller grain size which has higher specific surface area and porosity. Based on this study, the thickness of electrolyte layer YSZ doesn’t affect the basic characteristic of PEC but affect the efficiency of PEC significantly.

Abstract: TiO₂ nanotube (TNT) arrays were fabricated in NaOH/fluoride/ethylene glycol (EG) electrolyte at 30 V and 60 V for 60 min via anodization method. Three different concentrations of NaOH were studied: 1 M, 1.5 M and 2 M. Self-organized, vertically aligned and uniform nanotubes were produced for all samples but longer nanotubes were formed when 60 V was used instead of 30 V. The fabricated TNTs at 60 V were used as photoanode in a photoelectrochemical (PEC) cell. PEC cell with photoanode fabricated in 1 M NaOH/fluoride/EG electrolyte displayed photocurrent of 3.5 mA/cm² under light illumination.

Abstract: Anatase TiO₂ nanotube arrays with about 50nm pore diameter were prepared by anodic oxidation. The effect of the donor materials (sodium hydroxide, methanol and ethylene glycol) on electrochemistry impedance spectroscopy (EIS) and the photocurrent responses of TiO₂ nanotube arrays photoanode in the photoelectrochemical cell for splitting water hydrogen production were investigated. The results indicate that all the donor materials enhance the photocurrent responses and reduce the internal reaction resistances of the TiO₂ nanotube arrays photoanode. The effect of adding organic donor compounds in the anolyte on charge transfer and photocurrent is superior to the inorganic donor compounds and in turn reduces from the ethylene glycol, methanol to sodium hydroxide. Additionally, it should be highlighted that +0.3V vs. open circuit potential of applied potential on the electrode promotes a suitable charge transfer at semiconductor/electrolyte interface. The flat band potentials of TiO₂ nanotube arrays photoanode move to negative direction with donor materials adding in the anolyte which indicates beneficial photoelectrocatalytic hydrogen production by water splitting.

Abstract: The objective of this paper is to study the characteristic of a circular tube with a built-in arc belt on fluid flow and heat transfer in uniform wall temperature flows. Numerical simulations for hydrodynamically laminar flow was direct ran at Re between 600 and 1800. Preliminary results on velocity and temperature statistics for uniform wall temperature show that, arc belt can swirl the pipe fluid, so that the fluid at the center of the tube and the fluid of the boundary layer of the wall can mix fully, and plays the role of enhanced heat transfer, but also significantly increases the resistance of the fluid and makes the resistance coefficient of the enhanced tube greater than smooth tube. The combination property PEC is all above 1.5.

Abstract: In this study, an anodized TiO2 electrode (ATE) on a titanium foil was prepared and used as a photoanode in an enzymatic photoelectrochemical system to split water into oxygen and hydrogen. The effect of applied voltage when anodized, thickness of foil, electrolytes, annealing temperature, and species of cathode was investigated. The optimum conditions were obtained such as 0.25 mm foil thickness, 20V of applied voltage in 0.5 vol% of hydrofluoric acid, and 650 oC of annealing temperature. The samples with higher activities had similar X-ray diffraction (XRD) patterns, clearly indicating that the samples showing the highest evolution rate were composed of both anatase and rutile, while those showing a lower evolution rate were made of either anatase or rutile. Increasing the intensity of the irradiated light caused a remarkable enhancement in the rate of hydrogen production up to 153 μmol/(hr×cm2) under light intensity of 146 mW/cm2.