Metal‐Free Dehydrogenation of N‐Heterocycles by Ternary <i>h</i>‐BCN Nanosheets with Visible Light

Zheng, Meifang; Shi, Jiale; Tao, Yuan; Wang, Xinchen

doi:10.1002/anie.201800319

Cited by 156 publications

(68 citation statements)

References 81 publications

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“…The first realization of this concept is presented, Figure . Graphitic carbon nitride (g‐CN) is a photoactive semiconductor that absorbs blue light but was rarely used for the oxygenation of organic compounds, however, dehydrogenation of N‐heterocycles was reported . Upon visible‐light irradiation we suggest that hole–electron recombination can be inhibited by the attachment of a polyoxometalate, H 3 PW 12 O 40 , to the g‐CN material; the polyoxometalate acts as an electron acceptor and shuttle.…”

Section: Figurementioning

confidence: 94%

Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation

Neumann

Haviv

2020

Angewandte Chemie

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Research on the photochemical reduction of CO2, initiated already 40 years ago, has with few exceptions been performed by using amines as sacrificial reductants. Hydrocarbons are high‐volume chemicals whose dehydrogenation is of interest, so the coupling of a CO2 photoreduction to a hydrocarbon‐photodehydrogenation reaction seems a worthwhile concept to explore. A three‐component construct was prepared including graphitic carbon nitride (g‐CN) as a visible‐light photoactive semiconductor, a polyoxometalate (POM) that functions as an electron acceptor to improve hole–electron charge separation, and an electron donor to a rhenium‐based CO2 reduction catalyst. Upon photoactivation of g‐CN, a cascade is initiated by dehydrogenation of hydrocarbons coupled to the reduction of the polyoxometalate. Visible‐light photoexcitation of the reduced polyoxometalate enables electron transfer to the rhenium‐based catalyst active for the selective reduction of CO2 to CO. The construct was characterized by zeta potential, IR spectroscopy, thermogravimetry, scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDS). An experimental Z‐scheme diagram is presented based on electrochemical measurements and UV/Vis spectroscopy. The conceptual advance should promote study into more active systems.

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Section: Figurementioning

confidence: 94%

Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation

Neumann

Haviv

2020

Angewandte Chemie

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“…The acceptorless dehydrogenation of N‐heterocycles is an important reaction in organic synthesis, which also has potential in the storage of hydrogen . This reaction is usually carried out under thermal conditions, and recently shown possible to be catalyzed under visible light . The mechanism study revealed the multistep nature of the dehydrogenation process (Supporting Information, Figures S91, S92), which is suitable for the systematic study of MOFs with variable distance profiles.…”

Section: Figurementioning

confidence: 99%

“…This reaction is usually carried out under thermal conditions, and recently shown possible to be catalyzed under visible light . The mechanism study revealed the multistep nature of the dehydrogenation process (Supporting Information, Figures S91, S92), which is suitable for the systematic study of MOFs with variable distance profiles. In this study, we showed that porphyrin and porphyrin MOFs were also capable to dehydrogenate THQ under visible light.…”

Section: Figurementioning

confidence: 99%

“…Among these correlations, the plot with weighed average reciprocal of distance revealed a linear fitting with regression of r =0.99, and a slope of 9.7. Given the multistep nature of this photocatalytic reaction, we surmised that the value of this slope is related to the activity of the porphyrin center to generate reaction intermediate. When a different type of active site is used, this value might change.…”

Section: Figurementioning

confidence: 99%

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Metal–Organic Frameworks for the Exploitation of Distance between Active Sites in Efficient Photocatalysis

et al. 2020

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Discoveries of the accurate spatial arrangement of active sites in biological systems and cooperation between them for high catalytic efficiency are two major events in biology. However, precise tuning of these aspects is largely missing in the design of artificial catalysts. Here, a series of metal–organic frameworks (MOFs) were used, not only to overcome the limit of distance between active sites in bio‐systems, but also to unveil the critical role of this distance for efficient catalysis. A linear correlation was established between photocatalytic activity and the reciprocal of inter active‐site distance; a smaller distance led to higher activity. Vacancies created at selected crystallographic positions of MOFs promoted their photocatalytic efficiency. MOF‐525‐J33 with 15.6 Å inter active‐site distance and 33 % vacancies exhibited unprecedented high turnover frequency of 29.5 h−1 in visible‐light‐driven acceptorless dehydrogenation of tetrahydroquinoline at room temperature.

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“…Generally, the photocatalytic properties of semiconductors are strongly related to their crystallinity and surface properties, such as morphology, specific surface area, as well as surface feature. [33][34][35][36][37][38][39] Since the samples have similar morphological structures and specific surface areas, we explored their surface features. Herein, we investigated the atomic arrangement of the surface of BiOCl n Br 1-n .…”

Section: Mechanism Of the Alloying Effects On Improving The Photocatamentioning

confidence: 99%

A Mechanism Investigation of how the Alloying Effect Improves the Photocatalytic Nitrate Reduction Activity of Bismuth Oxyhalide Nanosheets

et al. 2019

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Alloyed bismuth oxyhalides have been widely used in photocatalytic water treatment processes due to their superior photocatalytic activity. However, there is no report on the removal of NO3− for alloyed bismuth oxyhalides, and the mechanism of the effect of alloying on NO3− reduction activity is still unclear. In this work, we prepared a series of BiOClnBr1‐n (0≤n≤1) with different Cl/Br ratios but with controlled similar morphologies, and explored their catalytic activities on reducing NO3− under visible light irradiation. Density functional theory investigations revealed that the formation energy for an oxygen (O) vacancy on the surface of BiOClnBr1‐n alloys is clearly reduced in comparison with the monohalide, illustrating that more O vacancies can be produced on the surface of BiOClnBr1‐n alloys. A high concentration of O vacancies not only promotes the adsorption of NO3− but also enhances the separation efficiency of the photogenerated electron‐hole (e–h) pairs, with both being beneficial to enhance the photocatalytic activity of BiOClnBr1‐n alloys for NO3− reduction. These new discoveries not only promote the design and development of new photocatalysts with excellent NO3− reduction properties, but also help to understand the relationship between alloying effects and semiconductor photocatalytic properties.

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Metal‐Free Dehydrogenation of N‐Heterocycles by Ternary h‐BCN Nanosheets with Visible Light

Cited by 156 publications

References 81 publications

Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation

Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation

Metal–Organic Frameworks for the Exploitation of Distance between Active Sites in Efficient Photocatalysis

A Mechanism Investigation of how the Alloying Effect Improves the Photocatalytic Nitrate Reduction Activity of Bismuth Oxyhalide Nanosheets

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Metal‐Free Dehydrogenation of N‐Heterocycles by Ternary h‐BCN Nanosheets with Visible Light

Cited by 156 publications

References 81 publications

Visible‐Light Photochemical Reduction of CO2 to CO Coupled to Hydrocarbon Dehydrogenation

Visible‐Light Photochemical Reduction of CO2 to CO Coupled to Hydrocarbon Dehydrogenation

Metal–Organic Frameworks for the Exploitation of Distance between Active Sites in Efficient Photocatalysis

A Mechanism Investigation of how the Alloying Effect Improves the Photocatalytic Nitrate Reduction Activity of Bismuth Oxyhalide Nanosheets

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Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation

Visible‐Light Photochemical Reduction of CO₂ to CO Coupled to Hydrocarbon Dehydrogenation