Covalent organic frameworks (COFs) are promising crystalline materials for photocatalytic solar- to hydrogen-energy conversion due to the tunable chemical structures and energy band gaps. Herein, we report a chemical modification strategy for improving the photocatalytic activity of COFs. A benzene-1,3,5-tricarbaldehyde (BT)- and benzothiadiazole derivative-based two-dimensional donor-acceptor (D-A) COF, denoted as BT-COF, were fabricated and further modified by using an alternative electron-donating unit, 2-hydroxybenzene-1,3,5-tricarbaldehyde (HBT), to the polycondensation reaction, yielding HBT-COF with an enhanced internal D-A effect and hydrophilicity. Interestingly, the photocatalytic H production rate of HBT-COF reaches 19.00 μmol h, which is 5 times higher than that of BT-COF (3.40 μmol h) under visible light irradiation. The increase in photocatalytic activity of HBT-COF is rationally attributed to finely tuned energy levels and improved wettability, which in turn leads to broadened visible light absorption, efficient photoinduced charge separation and transfer, and enhanced interactions between the COF catalyst and reaction substrates. The present results demonstrate that a subtle structural modification can significantly modulate the band structure and interfacial property, thus providing a feasible strategy for the optimization of COF-based photocatalytic systems.
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http://dx.doi.org/10.1021/acsami.1c04880 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Sociology, University of California, Irvine, CA 92697-5100.
In recent years, Brazil's non-White (Brown and Black) population became a numerical majority for the first time since the 19th century. Although we know this change was mostly due to racial reclassification, we do not know how such changes are related to skin color, the primary marker of race in Brazil. Using data from six Latin American Public Opinion Project (LAPOP), or America's Barometer, surveys from 2010 to 2023, we examine how changes in racial self-identification (White, Brown, or Black) are related to respondent skin color (light, medium, or dark).
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Section on Perception, Cognition, Action, Laboratory of Sensorimotor Research, National Eye Institute, NIH, Bethesda, MD 20892.
To what extent does concept formation require language? Here, we exploit color to address this question and ask whether macaque monkeys have color concepts evident as categories. Macaques have similar cone photoreceptors and central visual circuits to humans, yet they lack language. Whether Old World monkeys such as macaques have consensus color categories is unresolved, but if they do, then language cannot be required.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
Retinal ganglion cells (RGCs) typically respond to light stimulation over their spatially restricted receptive field. Using large-scale recordings in the mouse retina, we show that a subset of non- direction-selective (DS) RGCs exhibit asymmetric activity, selective to motion direction, in response to a stimulus crossing an area far beyond the classic receptive field. The extraclassical response arises via inputs from an asymmetric distal zone and is enhanced by desensitization mechanisms and an inherent DS component, creating a network of neurons responding to motion toward the optic disc.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong 10120, Thailand.
A single-component flavin-dependent halogenase, AetF, has emerged as an attractive biocatalyst for catalyzing halogenation. However, its flavin chemistry remains unexplored and cannot be predicted due to its uniqueness in sequence and structure compared to other flavin-dependent monooxygenases. Here, we investigated the flavin reactions of AetF using transient kinetics.
View Article and Find Full Text PDFHum Reprod
January 2025
IRSD, Université de Toulouse, INSERM, INRAE, ENVT, Univ Toulouse III-Paul Sabatier (UPS), Toulouse, France.
Study Question: Does a human fallopian tube (HFT) organoid model offer a favourable apical environment for human sperm survival and motility?
Summary Answer: After differentiation, the apical compartment of a new HFT organoid model provides a favourable environment for sperm motility, which is better than commercial media.
What Is Known Already: HFTs are the site of major events that are crucial for achieving an ongoing pregnancy, such as gamete survival and competence, fertilization steps, and preimplantation embryo development. In order to better understand the tubal physiology and tubal factors involved in these reproductive functions, and to improve still suboptimal in vitro conditions for gamete preparation and embryo culture during IVF, we sought to develop an HFT organoid model from isolated adult stem cells to allow spermatozoa co-culture in the apical compartment.
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