Hong Kong Institute of Education

About: Hong Kong Institute of Education is a based out in . It is known for research contribution in the topics: Curriculum & Teacher education. The organization has 1426 authors who have published 3415 publications receiving 99729 citations.

In situ construction of g-C3N4/g-C3N4 metal-free heterojunction for enhanced visible-light photocatalysis.

Abstract: The photocatalytic performance of the star photocatalyst g-C3N4 was restricted by the low efficiency because of the fast charge recombination. The present work developed a facile in situ method to construct g-C3N4/g-C3N4 metal-free isotype heterojunction with molecular composite precursors with the aim to greatly promote the charge separation. Considering the fact that g-C3N4 samples prepared from urea and thiourea separately have different band structure, the molecular composite precursors of urea and thiourea were treated simultaneously under the same thermal conditions, in situ creating a novel layered g-C3N4/g-C3N4 metal-free heterojunction (g-g CN heterojunction). This synthesis method is facile, economic, and environmentally benign using easily available earth-abundant green precursors. The confirmation of isotype g-g CN heterojunction was based on XRD, HRTEM, valence band XPS, ns-level PL, photocurrent, and EIS measurement. Upon visible-light irradiation, the photogenerated electrons transfer from ...

Sulfur-doped g-C3N4 with enhanced photocatalytic CO2-reduction performance

Abstract: Graphitic carbon nitride (g-C 3 N 4 ) is the most stable phase of all carbon nitride allotropes under ambient conditions. In this study, sulfur-doped g-C 3 N 4 was fabricated by simply calcinating thiourea at 520 °C. Sulfur-doped g-C 3 N 4 (TCN) was found to absorb light up to 475 nm corresponding to a band gap of 2.63 eV, which was narrower than that of un-doped g-C 3 N 4 (MCN) with a band gap of 2.7 eV. First-principle calculations based on spin-polarized density functional theory were utilized to investigate the theoretical partial density of states of the TCN and MCN, indicating that the band gaps of TCN and MCN were the same, but impurities existed in the TCN sample. Consequently, photogenerated electrons could easily jump from the impurity state to the conduction band or from the valence band to the impurity state. Photocatalytic CO 2 reduction was further used to evaluate the photoactivity of samples, and the CH 3 OH yield using TCN and MCN were 1.12 and 0.81 μmol g −1 , respectively. PL spectrum analysis and transient photocurrent responses were also carried out to verify the suggested photocatalysis mechanism.

Application of majority voting to pattern recognition: an analysis of its behavior and performance

Abstract: It has been demonstrated that combining the decisions of several classifiers can lead to better recognition results. The combination can be implemented using a variety of strategies, among which majority vote is by far the simplest, and yet it has been found to be just as effective as more complicated schemes in improving the recognition results. This paper examines the mode of operation of the majority vote method in order to gain a deeper understanding of how and why it works, so that a more solid basis can be provided for its future applications to different data and/or domains. In the course of our research, we have analyzed this method from its foundations and obtained many new and original results regarding its behavior. Particular attention has been directed toward the changes in the correct and error rates when classifiers are added, and conditions are derived under which their addition/elimination would be valid for the specific objectives of the application. At the same time, our theoretical findings are compared against experimental results, and these results do reflect the trends predicted by the theoretical considerations.

Peer feedback: the learning element of peer assessment

Abstract: This paper focuses on peer feedback in relation to assessment processes. It examines the rationale for peer feedback, emphasizing its potential for enhanced student learning. We draw on relevant literature to argue that the dominance of peer assessment processes using grades can undermine the potential of peer feedback for improving student learning. The paper throws further light on the issue by drawing on a large-scale questionnaire survey of tertiary students (1740) and academics (460) in Hong Kong, supplemented by interview data. The findings indicate that a significant number of academics and students resist peer assessment using grades and that the majority report that students never or rarely grade each other in assessment activities. This paper explores why there is resistance, in particular, by academics to peer assessment and argues the case for a peer feedback process as an end in itself or as a precursor to peer assessment involving the awarding of marks. It also recommends some strategies for...