Microreactors have garnered widespread attention for their tunability and precise control of synthetic parameters to efficiently produce target species. Despite associated advances, a lack of online detection and optimization methods has stalled the progression of microfluidic reactors. Here we employ and characterize a total internal reflection transient absorption microscopy (TIRTAM) instrument to image excited state dynamics on a continuous flow device. The experiments presented demonstrate the capability to discriminate between different chromophores as well as in differentiating the effects of local chemical environments that a chromophore experiences. This work presents the first such online transient absorption measurements and provides a new direction for the advancement and optimization of chemical reactions in microfluidic devices.
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http://dx.doi.org/10.1021/acs.jpca.9b12046 | DOI Listing |
Nat Commun
January 2025
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore, Singapore.
Photocatalytic conversion has emerged as a promising strategy for harnessing renewable solar energy in the valorization of plastic waste. However, research on the photocatalytic transformation of plastics into valuable nitrogen-containing chemicals remains limited. In this study, we present a visible-light-driven pathway for the conversion of polylactic acid (PLA) into alanine under mild conditions.
View Article and Find Full Text PDFDalton Trans
January 2025
Institute for Organic Synthesis and Photoreactivity (ISOF) - National Research Council (CNR), Via P. Gobetti 101, 40129 Bologna, Italy.
A supramolecular system, consisting of a tetrapyrenylporphyrinic core surrounded by arene-ruthenium prisms, has been assembled and characterized by means of electrochemical and photophysical techniques. The photophysical study shows that quantitative energy transfer from the peripheral pyrenyl units towards the central porphyrin core is operative in the tetrapyrenylporphyrinic system. Interestingly, encapsulation of the pyrenyl units into the ruthenium cages affects the photophysics of the central porphyrin component, since its emission quantum yield is reduced in the supramolecular array.
View Article and Find Full Text PDFNanoscale
January 2025
Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Loading cocatalysts on semiconductor-based photocatalysts to create active reaction sites is a preferable method to enhance photocatalytic activity and a widely adopted strategy to achieve effective photocatalytic applications. Although theoretical calculations suggest that the broad density of states of noble metal cocatalysts, such as Pt, act as a recombination center, this has never been experimentally demonstrated. Herein, we employed pico-nano and nano-micro second transient absorption spectroscopy to investigate the often overlooked photogenerated holes, instead of the widely studied electrons on Pt- and Ni-loaded SrTiO to evaluate the effects of cocatalysts as a recombination center.
View Article and Find Full Text PDFNatl Sci Rev
January 2025
Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Constructing 3D functional covalent organic frameworks (COFs) with both robust linkage and planar macrocycle building blocks still remains a challenge due to the difficulty in adjusting both the crystallinity and the dominant 2D structures. In addition, it is also challenging to selectively convert inert C(sp)-H bonds into value-added chemicals. Herein, robust 3D COFs, USTB-28-M (M=Co, Ni, Cu), have been polymerized from the nucleophilic aromatic substitution reaction of -symmetric 2,3,6,7,14,15-hexahydroxyltriptycene with -symmetric hexadecafluorophthalocyanine (MPcF) under solvothermal conditions.
View Article and Find Full Text PDFACS Omega
January 2025
Innovation Research Center for Fuel Cells and Hydrogen, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585, Japan.
There is a large gap between the performances indicated by rotating disk electrode (RDE) results in acidic media and the actual performances obtained in membrane-electrode assemblies (MEAs) composed of the same electrocatalysts. It is unclear whether the intrinsic kinetic reactivity of the available surface Pt sites of Pt-based cathode electrocatalysts is similar or different at RDE and in MEA. To address this, we used an operando element-selective time-resolved Pt L-edge quick X-ray absorption fine structure (QXAFS) technique to determine transient response profiles and rate constants, , , and , corresponding to changes in the oxidation states [white line (WL) intensity] and local structures (coordination numbers of Pt-O and Pt-Pt bonds) at Pt sites for nine representative Pt-based cathode electrocatalysts under transient voltage operations, aiming to understand the oxygen reduction reaction (ORR) performance gap between RDE and MEA.
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