•This work confirms the importance of MIN as a useful modifier of semiconductor photocatalysts and catalysts doped with noble metals.•The MIN has a surface passivation effect that inhibits the aggregation and oxidation of Cu2O. This enhances its wettability and stability, improves crystallinity and reduces Au particle sizes.•The MIN promotes charge transfer via tunneling through the insulator, and enhances adsorption of molecular oxygen, facilitating active oxygen formation during photocatalysis.In this study, the interface effects of Cu2O and Au/Cu2O semiconductors were improved by addition of a magnesia (MgO) interface nanolayer (MIN) deposited via precipitation. The morphologies, crystal structures, chemical compositions, elemental states and optical properties of MgO/Cu2O and Au/MgO/Cu2O heterojunctions were characterized via SEM, XRD, XPS, UV–VIS–NIR and PL. It was found that the MIN has a surface passivation effect that inhibits the aggregation and oxidation of Cu2O. This enhances Cu2O semiconductors’ wettability and stability, improves crystallinity and reduces Au particle sizes. More importantly, the MIN promotes charge transfer via tunneling through the insulator, and enhances adsorption of molecular oxygen, facilitating superoxide radicals formation during photoreactivity. MgO/Cu2O and Au/MgO/Cu2O exhibited superior photodegradation of methyl orange, attributed to the boost of O2− and h+. This work confirmed the importance of MIN as a useful modification of semiconductor photocatalysts, and the MIN can significantly enhance the production of superoxide radicals in the photocatalytic activity with visible light.Download high-res image (173KB)Download full-size image

Treatment of seven types of natural organic matter (NOM) with sodium borohydride (NaBH4), a selective reductant of carbonyl-containing functional groups, results in significantly decreased photoproduction of Au nanoparticles (Au0) from Au3+. Comparison of these results with those obtained from a series of model aromatic ketones and quinones demonstrates that these reaction rate changes after NaBH4 treatment can be largely assigned to the aromatic ketone moieties in NOM. Moreover, these results are consistent with the charge-transfer model in which charge-transfer transitions arise among hydroxy-aromatic donors and carbonyl-containing acceptors. Electron paramagnetic resonance (EPR) analysis also uniformly indicates the important role of carbonyl-containing moieties in superoxide radical (O2˙−) generation and denies that of phenolic moieties.

Problems are an important part of teaching and important for achieving the creative education targets for graduates and upper-division undergraduates. Besides classical problems in textbooks, problems from recent research should be involved in class, too. This article reports how literature-based problems were incorporated in a scalable manner in a large-scale graduate course of organic structure analysis with widely varying levels of student preparedness at the University of Chinese Academy of Sciences. Two literature based problem designing cases were detailed, aiming at bringing possibilities and challenges to the students that are highly welcomed by them, and more such problems were provided further. The implications for both students and teachers were discussed to guide the future designing of more effective problems. These problems give students experience in modern scientific research in a large-scale class and build upon a habit that strongly emphasizes research-style thinking.

As worldwide energy shortages and environmental degradation increase, along with steady increases in population, current science and technology are confronted with many challenges to successfully sustain our society. Among the existing promising choices, photocatalysis has been widely considered as a potential solution to energy and environment problems because of its double functions of producing H2 fuel directly from water and efficiently decomposing organic pollutants. This paper reports on the teaching experience of a graduate course—Photocatalysis: Principles and Applications—in the 2011–2012 spring term at University of Chinese Academy of Sciences (UCAS), mainly involving the teaching materials, literature discussion, and students’ feedback. During instruction, great efforts were made to introduce state-of-the-art research activities as well as related opportunities and challenges identified in top research papers, which are well received by the students. Feedback collected from the students was analyzed and is discussed, in order to improve this course accordingly. In addition, suggestions for potential yet non-expert instructors are provided, as well as ways to adapt the course for undergraduates.Keywords: Environmental Chemistry; Free Radicals; Graduate Education/Research; Inquiry-Based/Discovery Learning; Interdisciplinary/Multidisciplinary; Materials Science; Nanotechnology; Oxidation/Reduction; Photochemistry; Upper-Division Undergraduate;

Treatment of seven types of natural organic matter (NOM) with sodium borohydride (NaBH4), a selective reductant of carbonyl-containing functional groups, results in significantly decreased photoproduction of Au nanoparticles (Au0) from Au3+. Comparison of these results with those obtained from a series of model aromatic ketones and quinones demonstrates that these reaction rate changes after NaBH4 treatment can be largely assigned to the aromatic ketone moieties in NOM. Moreover, these results are consistent with the charge-transfer model in which charge-transfer transitions arise among hydroxy-aromatic donors and carbonyl-containing acceptors. Electron paramagnetic resonance (EPR) analysis also uniformly indicates the important role of carbonyl-containing moieties in superoxide radical (O2˙−) generation and denies that of phenolic moieties.