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2,605 results on '"Tung, Chen-Ho"'

156. Covalent organic framework and hydrogen-bonded organic framework for solar-driven photocatalysis.

Author

Qin, Wei-Kang, Tung, Chen-Ho, and Wu, Li-Zhu

Abstract

The newly emerging porous crystalline materials, covalent organic framework (COF) and hydrogen-bonded organic framework (HOF), are characterized by their large surface area, considerable structural diversity, and functional tailorability. Combining these properties, they are considered to have the potential for photocatalysis. This review summarizes their advantages and compatibility, particularly focusing on design strategies to overcome the existing issues of poor charge conductivity and deficient active sites. With representative examples of solar-driven hydrogen (H2) evolution and carbon dioxide (CO2) reduction, the exploration and expectation of such functional porous materials are presented. [ABSTRACT FROM AUTHOR]

Published
2023
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176. Direct N−H Activation to Generate Nitrogen Radical for Arylamine Synthesis via Quantum Dots Photocatalysis.

Author

Gan, Qi‐Chao, Qiao, Jia, Zhou, Chao, Ci, Rui‐Nan, Guo, Jia‐Dong, Chen, Bin, Tung, Chen‐Ho, and Wu, Li‐Zhu

Subjects
QUANTUM dot synthesis, RADICALS (Chemistry), ARYL halides, PHOTOCATALYSIS, QUANTUM dots, ORGANIC synthesis, AROMATIC amines
Abstract

Represented herein is the first example of N‐radical generation direct from N−H bond activation under mild and redox‐neutral conditions. The in situ generated N‐radical intercepts a reduced heteroarylnitrile/aryl halide for C−N bond formation under visible‐light irradiation of quantum dots (QDs). A series of aryl and alkylamines with heteroarylnitriles/aryl halides exhibit high efficiency, site‐selectivity and good functional‐group tolerance. Moreover, consecutive C−C and C−N bond formation using benzylamines as substrates is also achieved, producing N‐aryl‐1,2‐diamines with H2 evolution. The redox‐neutral conditions, broad substrate scope, and efficiency of N‐radical formation are advantageous for organic synthesis. [ABSTRACT FROM AUTHOR]

Published
2023
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177. A butterfly-like lead-doped titanium-oxide compound with high performance in photocatalytic cycloaddition of CO2 to epoxide.

Author

Said, Amir, Zhang, Guanyun, Liu, Caiyun, Wang, Dexin, Niu, Huihui, Liu, Yanshu, Chen, Guanjie, Tung, Chen-Ho, and Wang, Yifeng

Subjects
RING formation (Chemistry), LEWIS acidity, CATALYTIC activity, EPOXY compounds, X-ray diffraction
Abstract

The cycloaddition reaction of CO2 to epoxides is quite promising for CO2 capture and storage as well as the production of value-added fine chemicals. Herein, a novel atomically precise lead-doped titanium-oxide cluster with the formula Ti10Pb2O16(phen)4(Ac)12(DMF)2 (denoted as Ti10Pb2; phen = 1,10-phenanthroline; Ac = acetate; DMF = dimethylformamide) was synthesized through a facile solvothermal process, and is a molecular photocatalyst with surface-anchored main-group metal active sites. Its structure was characterized by single-crystal X-ray diffraction and other complementary techniques. Ti10Pb2 showed high photo-response and charge-separation efficiency under simulated sunlight irradiation. Ti10Pb2 was successfully used in the cycloaddition reaction of CO2 with epoxides under solvent-free conditions. While its catalytic activity due to the Lewis acidity was moderate, simulated solar light irradiation further enhanced the reaction rate, demonstrating the synergistic effect of photocatalysis and Lewis-acid thermocatalysis. [ABSTRACT FROM AUTHOR]

Published
2023
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178. Anion vacancy correlated photocatalytic CO2 to CO conversion over quantum-confined CdS nanorods under visible light.

Author

Guo, Qing, Xia, Shu-Guang, Xin, Zhi-Kun, Wang, Yang, Liang, Fei, Nan, Xiao-Lei, Lin, Zhe-Shuai, Li, Xu-Bing, Tung, Chen-Ho, and Wu, Li-Zhu

Abstract

Surface vacancies in II–VI semiconductors have been confirmed as active sites for photocatalytic CO2 reduction. Here we take quantum-confined CdS nanorod as a model photocatalyst to correlate anion vacancies with photocatalytic CO2 reduction performance. In terms of electronic structure change, CdS nanorods with more surface S vacancies give enhanced CO generation rates, which were confirmed by deliberately introducing S vacancies via a post-treatment. [ABSTRACT FROM AUTHOR]

Published
2023
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181. Direct Excitation of Aldehyde to Activate the C(sp2)−H Bond by Cobaloxime Catalysis toward Fluorenones Synthesis with Hydrogen Evolution.

Author

Guo, Jia‐Dong, Chen, Ya‐Jing, Wang, Chen‐Hong, He, Qiao, Yang, Xiu‐Long, Ding, Tian‐Yu, Zhang, Ke, Ci, Rui‐Nan, Chen, Bin, Tung, Chen‐Ho, and Wu, Li‐Zhu

Subjects
HYDROGEN production, COBALOXIMES, XANTHONE, METAL catalysts, CATALYSIS, AROMATIC aldehydes, HYDROGEN evolution reactions
Abstract

A new way to form fluorenones via the direct excitation of substrates instead of photocatalyst to activate the C(sp2)−H bond under redox‐neutral condition is reported. Our design relies on the photoexcited aromatic aldehyde intermediates that can be intercepted by cobaloxime catalyst through single electron transfer for following β‐H elimination. The generation of acyl radical and successful interception by a metal catalyst cobaloxime avoid the use of a photocatalyst and stoichiometric external oxidants, affording a series of highly substituted fluorenones, including six‐membered ketones, such as xanthone and thioxanthone derivatives in good to excellent yields, and with hydrogen as the only byproduct. This catalytic system features a readily available metal catalyst, mild reaction conditions and broad substrate scope, in which sunlight reaction and scale‐up experiments by continuous‐flow approach make the new methodology sustainable and amenable for potentially operational procedures. [ABSTRACT FROM AUTHOR]

Published
2023
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