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The purposes of this study were to investigate students' conceptual learning outcomes and the effect of motivation on students' conceptual learning outcomes in two different contexts: a Web-based and a classroom-based instruction, which incorporated the Dual Situation Learning Model (DSLM). Nine classes of Grade eight students (N = 190) were involved in the study; five classes participated in a Web-based context and four classes in a regular classroom-based context. The topic covered was chemical reaction. Students' conceptual change outcomes were assessed using eight two-tier pre/post conceptual tests during the instruction and the reaction rate integrated conceptual test at the end of the instruction. Students' motivation data were collected in the beginning and during instruction using the items from the Students' Motivation Toward Science Learning (SMTSL) questionnaire. The data were analyzed using ANOVA, ANCOVA, bivariate correlation, and multiple regression analysis. Findings revealed that students' motivational factors were correlated significantly with their conceptual learning outcomes in both Web-based and classroom-based science teaching. In the Web-based context, students' motivation during the Web-based learning played a more important role on students' conceptual learning outcomes than before learning.

Abstract: One of the best routes to covert CO2 into energy and simultaneously reduce atmospheric CO2 is photosynthesis. In natural photosynthesis, the first step is water splitting in which proton is generated and O2 is released using solar energy. The second step is the Calvin cycle in which CO2 is reduced to hydrocarbons. This study demonstrated the photocatalytic hydrogenation of CO2 by using a novel twin reactor to mimic photosynthesis process in nature. The twin reactor, which divided H2-generating photocatalyst and O2-generating photocatalyst in two compartments using a membrane, first achieved separate H2 and O2 evolution to prevent the backward reaction to form water under visible light irradiation. The generated hydrogen was then used to perform CO2 hydrogenation by CO2 reduction photocatalyst. The advantage is that CO2 hydrogenation is a spontaneous reaction based on the thermodynamics. The single photocatalyst system using Pt/CuAlGaO4 as both H2-generating photocatalyst and CO2 reduction photocatalyst, was compared with the dual photocatalyst system using Pt/SrTiO3:Rh and Pt/CuAlGaO4 as H2-generating photocatalyst and CO2 reduction photocatalyst, respectively, under simulated sunlight AM1.5G. The dual photocatalyst system has demonstrated photoreduction quantum efficiency (PQE) of 0.0051%, which is more than doubled the PQE of the single photocatalyst system. [Copyright &y& Elsevier]

ABSTRACT Visible-light absorbing TiO2 (vis-TiO2) and WO3 (vis-WO3) photocatalytic thin films were prepared by radio-frequency magnetron sputtering. The effect of heat treatment on thin film properties was investigated. Instrumental analyses such as X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, and ultraviolet-visible absorption spectrometry were performed to reveal the crystallinity, surface morphology, chemical composition, and light absorption of the prepared thin films. To further enhance the photoactivity of the prepared thin films, a dual-layer photoelectrode (DLP) that consists of both vis-TiO2 and vis-WO3 was fabricated. Moreover, photoactivities of the prepared single and dual-layer photoelectrodes under both ultraviolet and visible-light irradiations were evaluated by conducting photovoltammetry as well as water-splitting reaction in an H-type reactor. It was demonstrated that the H2 and O2 yields obtained from water-splitting reaction are consistent with the photocurrent results, showing that DLP is more photoactive than single-layer photoelectrode. The enhanced performance of DLP is mainly attributed to the improved charge separation of the dual-layer structure. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Photocatalytic TiO2 thin films were prepared via an electron beam-induced deposition (EBID) method. The effects of post-calcination treatment on the properties of the prepared TiO2 thin films were studied. X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometry (SEM-EDS), and UV–V is absorption spectrometry were performed to reveal the crystallinity, surface morphology, chemical composition, and light absorbance of the prepared TiO2 thin films. The photoelectrochemical characteristics of the TiO2 thin films were investigated with a potentiostat. Under UV irradiation, a photocurrent of ˜2.1 mA was observed for the TiO2 thin film with post-calcination at 500 °C. A water-splitting reaction was conducted over the TiO2 thin film with the best photoelectrochemical performance. The yields of hydrogen and oxygen were 59.8 and 30.6 μmole, respectively, after 8 h of reaction under UV irradiation. [ABSTRACT FROM AUTHOR]