Search query: boosting photocatalytic oxidative coupling of amines

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abstract: Abstract Visible light driven selective photocatalytic organic synthesis has recently become a topic of great interest due to its environmental friendliness and sustainability. It is demanding for photocatalysis to utilize the wider range of light, such as visible light, and its performance is often plagued by the sluggish separation of photogenerated charge carriers. An approach is now reported to address these issues by incorporating light harvesting RuII polypyridyl complexes into a semiconductor type metal organic framework (MIL 125) Delightedly, the obtained Ru(bpy)3@MIL 125 photocatalyst presents a remarkably stable and high photoactivity toward the selective oxidative coupling of amines under ambient air with visible light irradiation (l 440 nm) The mechanistic investigation unveiled that both effectively photoexcited electrons transfer from [Ru(bpy)3]Cl2 to MIL 125 and the interaction of C H bonds with superoxide radical (O2* play a critical role in photo catalyzing selective aerobic oxidative coupling of amines. This work highlights a significant role of MOFs as heterogeneous photocatalysts in photocatalytic organic transformations.
author_names: X Yang

Tao Huang

Shui-Ying Gao

Rong Cao
title: Boosting photocatalytic oxidative coupling of amines by a Ru complex sensitized metal organic framework
venue: Journal of Catalysis
year: 2019

abstract: Adsorption and activation of molecules on a surface holds the key to heterogeneous catalysis toward aerobic oxidative reactions. To achieve high catalytic activities, a catalyst surface should be rationally tailored to interact with both organic substrates and oxygen molecules. Here, a facile bottom up approach to defective tungsten oxide hydrate (WO3 *H2 O) nanosheets that contain both surface defects and lattice water is reported. The defective WO3 *H2 O nanosheets exhibit excellent catalytic activity for aerobic coupling of amines to imines. The investigation indicates that the oxygen vacancies derived from surface defects supply coordinatively unsaturated sites to adsorb and activate oxygen molecules, producing superoxide radicals. More importantly, the Bronsted acid sites from lattice water can contribute to enhancing the adsorption and activation of alkaline amine molecules. The synergistic effect of oxygen vacancies and Bronsted acid sites eventually boosts the catalytic activity, which achieves a kinetic rate constant of 0.455 h 1 and a turnover frequency of 0.85 h 1 at 2 h, with the activation energy reduced to 35 kJ mol 1 This work provides a different angle for metal oxide catalyst design by maneuvering subtle structural features, and highlights the importance of synergistic effects to heterogeneous catalysts.
author_names: Ning Zhang

Xiyu Li

Yifei Michelle Liu

Ran Long

Mengqiao Li

Shuangming Chen

Zeming Qi

Chengming Wang

Li Song

Jun Jiang

Yujie Xiong
title: Defective Tungsten Oxide Hydrate Nanosheets for Boosting Aerobic Coupling of Amines: Synergistic Catalysis by Oxygen Vacancies and Bronsted Acid Sites.
venue: Small
year: 2017

abstract: The plasmonic electron oscillations in optically excited metallic nanoparticles result in surface confinement of photon energy over much longer time scales in comparison to the unconfined photons traveling at the speed of light, thereby producing an enormous buildup of photon intensity and highly concentrated energetic hot electrons at the nanoparticle surfaces. While the plasmonic hot electrons can be harnessed to drive unconventional photocatalytic molecular transformations at the nanoparticle molecule interfaces, a set of fundamentally important issues concerning detailed reaction mechanisms still remain poorly understood. Here we use surface enhanced Raman scattering (SERS) as a unique time resolving and molecular finger printing tool to spectroscopically resolve the complex kinetics and underlying pathways of plasmon driven oxidative coupling of thiophenol derivatives chemisorbed on the surfaces of optically excited plasmonic Ag nanostructures. A hybrid suprananostructure composed of an SiO2 bead den.
author_names: Qingfeng Zhang

Hui Wang
title: Mechanistic Insights on Plasmon Driven Photocatalytic Oxidative Coupling of Thiophenol Derivatives: Evidence for Steady State Photoactivated Oxygen
year: 2018

abstract: Diminishing fossil fuels and global warming issues have forced the scientists to look for alternative sources of energy to cater to the ever increasing demand. Artificial systems are being developed in order to mimic natural photosynthesis and directly harvest and convert solar energy into renewable energy and environmental remediation. Despite significant efforts, it has not been possible to design a single material which has sufficient efficiency, stability and low cost. To integrate the desired characteristics into a single component, heterogeneous photocatalysts are designed with multiple functional components which could combine the advantages of different components to overcome the drawbacks of single component photocatalysts. The present highlight gives a concise overview of heterogeneous catalysts that have been developed and studied in our group and some excellent works of others in recent years. The review focuses on the principles of photocatalytic and electrocatalytic activities followed by some key examples of oxide based materials. This includes a wide range of structural modification and crystal growth processes leading to composites, heterostructures, including insulator/semiconductor, semiconductor/semiconductor, and multi heteronanostructures, and core shell nanostructures which have been modified in order to improve the performance by increasing the light absorption, promoting the charge separation and transportation, and enhancing the redox catalytic activity and intrinsic electrocatalytic properties. The electrochemical processes like hydrogen evolution reaction (HER) oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) have been discussed closely on the effects of size, shape, exposed facets and surface area of electrocatalysts (metal oxides)
author_names: Aparna Ganguly

Oruganti Anjaneyulu

Kasinath Ojha

Ashok Kumar Ganguli
title: Oxide based nanostructures for photocatalytic and electrocatalytic applications
year: 2015

abstract: This work demonstrates the first molecular level conversion pathway of NO oxidation over a novel SrO clusters@amorphous carbon nitride (SCO ACN) photocatalyst, which is synthesized via copyrolysis of urea and SrCO3. The inclusion of SrCO3 is crucial in the formation of the amorphous carbon nitride (ACN) and SrO clusters by attacking the intralayer hydrogen bonds at the edge sites of graphitic carbon nitride (CN) The amorphous nature of ACN can promote the transportation, migration, and transformation of charge carriers on SCO ACN. And the SrO clusters are identified as the newly formed active centers to facilitate the activation of NO via the formation of Sr NOd( which essentially promotes the conversion of NO to the final products. The combined effects of the amorphous structure and SrO clusters impart outstanding photocatalytic NO removal efficiency to the SCO ACN under visible light irradiation. To reveal the photocatalytic mechanism, the adsorption and photocatalytic oxidation of NO over CN and SCO ACN are analyzed by in situ DRIFTS, and the intermediates and conversion pathways are elucidated and compared. This work presents a novel in situ DRIFTS based strategy to explore the photocatalytic reaction pathway of NO oxidation, which is quite beneficial to understand the mechanism underlying the photocatalytic reaction and advance the development of photocatalytic technology for environmental remediation.
author_names: Wenquan Cui

Jieyuan Li

Fan Dong

Yanjuan Sun

Guangming Jiang

Wanglai Cen

Shun Cheng Lee

Zhongbiao Wu
title: Highly Efficient Performance and Conversion Pathway of Photocatalytic NO Oxidation on SrO Clusters@Amorphous Carbon Nitride.
venue: Environmental science technology
year: 2017

abstract: A green and efficient approach for efficient nanohybrid photocatalysts in extending the light response to the visible spectrum is a hot research topic in sustainable energy technologies. In this work, novel Au TiO2@m CN nanocomposite was synthesized using hard template of cubic ordered mesoporous KIT 6 via the nanocasting process. The as prepared Au TiO2@m CN nanohybrids exhibit enhanced photocatalytic activities with improved stability and reusability using methyl orange dye. The enhanced photocatalytic performance is a result of the conjugated effect of catalytic active Au and TiO2 nanoparticles supported on highly efficient visible light sensitizer, graphitic carbon nitride (m CN or g C3N4) and ordered mesoporous morphology. Besides, the sensing performance of Au TiO2@m CN nanohybrids was also tested for the detection of amine gases, wherein a significant response was reported for triethylamine at low operating temperatures. This study reveals a simple and scalable methodology to design and develop next generation of layered mesoporous materials for multifunctional applications.
author_names: Ritu Malik

Vijay K Tomer

Nirav Joshi

Torben Dankwort

Liwei Lin

Lorenz Kienle
title: Au TiO2 Loaded Cubic g C3N4 Nanohybrids for Photocatalytic and Volatile Organic Amine Sensing Applications.
venue: ACS applied materials interfaces
year: 2018

abstract: Photocatalytic and photoelectrochemical water splitting under irradiation by sunlight has received much attention for production of renewable hydrogen from water on a large scale. Many challenges still remain in improving energy conversion efficiency, such as utilizing longer wavelength photons for hydrogen production, enhancing the reaction efficiency at any given wavelength, and increasing the lifetime of the semiconductor materials. This introductory review covers the fundamental aspects of photocatalytic and photoelectrochemical water splitting. Controlling the semiconducting properties of photocatalysts and photoelectrode materials is the primary concern in developing materials for solar water splitting, because they determine how much photoexcitation occurs in a semiconductor under solar illumination and how many photoexcited carriers reach the surface where water splitting takes place. Given a specific semiconductor material, surface modifications are important not only to activate the semiconductor for water splitting but also to facilitate charge separation and to upgrade the stability of the material under photoexcitation. In addition, reducing resistance loss and forming p n junction have a significant impact on the efficiency of photoelectrochemical water splitting. Correct evaluation of the photocatalytic and photoelectrochemical activity for water splitting is becoming more important in enabling an accurate comparison of a number of studies based on different systems. In the latter part, recent advances in the water splitting reaction under visible light will be presented with a focus on non oxide semiconductor materials to give an overview of the various problems and solutions.
author_names: Takashi Hisatomi

Jun Kubota

Kazunari Domen
title: Recent advances in semiconductors for photocatalytic and photoelectrochemical water splitting.
venue: Chemical Society reviews
year: 2014

abstract: Deuterium labeling is of great value in organic synthesis and the pharmaceutical industry. However, the state of the art C H/C D exchange using noble metal catalysts or strong bases/acids suffers from poor functional group tolerances, poor selectivity and lack of scope for generating molecular complexity. Herein, we demonstrate the deuteration of halides using heavy water as the deuteration reagent and porous CdSe nanosheets as the catalyst. The deuteration mechanism involves the generation of highly active carbon and deuterium radicals via photoinduced electron transfer from CdSe to the substrates, followed by tandem radicals coupling process, which is mechanistically distinct from the traditional methods involving deuterium cations or anions. Our deuteration strategy shows better selectivity and functional group tolerances than current C H/C D exchange methods. Extending the synthetic scope, deuterated boronic acids, halides, alkynes, and aldehydes can be used as synthons in Suzuki coupling, Click reaction, C H bond insertion reaction etc. for the synthesis of complex deuterated molecules.Developing convenient deuterium labeling procedures is important in organic synthesis and the pharmaceutical industry. Here, the authors report a mild photocatalytic strategy for controllable deuteration of halides using D2O as the reagent and porous CdSe nanosheets as the catalyst.
author_names: Cuibo Liu

Zhongxin Chen

Chenliang Su

Xiaoxu Zhao

Qiang Gao

Guo-Hong Ning

Hai Zhu

Wei Tang

Kai Leng

Wei Fu

Bingbing Tian

Xinwen Peng

Jing Li

Qing-Hua Xu

Wu Zhou

Kian Ping Loh
title: Controllable deuteration of halogenated compounds by photocatalytic D2O splitting
venue: Nature Communications
year: 2017

abstract: Abstract Photocatalytic hydrogen production via solar water splitting is one of the most promising solutions for sustainable energy and environmental remedy issues. In the past few decades, photocatalytic water splitting has attracted increasing attention, and extensive efforts have been made to construct efficient heterogeneous water splitting systems. In this chapter, we review the fundamental scientific advances in photocatalytic water splitting using semiconductor based photocatalyst, especially in light absorbing materials, photogenerated charge separation, dual cocatalyst, and surface catalytic reactions. The chapter focuses on the advances achieved in particulate photocatalyst systems, Z scheme photocatalyst systems, and hybrid natural artificial photosynthesis systems. Additionally, technical and economic evaluation of hydrogen production via solar water splitting for potential applications is also briefly discussed. Finally, we present concluding remarks and future directions of photocatalytic water splitting for solar energy conversion.
author_names: Rengui Li

Can Li
title: Photocatalytic Water Splitting on Semiconductor Based Photocatalysts
year: 2017

abstract: Processable, single layered graphene oxide (GO) is an intriguing nanomaterial with tremendous potential for electronic applications. We spin coated GO thin films on quartz and characterized their sheet resistance and optical transparency using different reduction treatments. A thermal graphitization procedure was most effective, producing films with sheet resistances as low as 10(2) 10(3) Omega/square with 80% transmittance for 550 nm light. Our experiments demonstrate solution processed GO films have potential as transparent electrodes.
author_names: Hector A Becerril

Jie Mao

Zunfeng Liu

Randall M Stoltenberg

Zhenan Bao

Yongsheng Chen
title: Evaluation of solution processed reduced graphene oxide films as transparent conductors.
venue: ACS nano
year: 2008