On the question of the optimal concentration of benzoquinone when it is used as a radical scavenger

Shtarev, Dmitry S.; Shtareva, Anna V.; Blokh, Artem I.; Goncharova, P. S.; Makarevich, Konstantin S.

doi:10.1007/s00339-017-1193-x

Cited by 21 publications

(9 citation statements)

References 16 publications

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“…In addition, the radicals and hole‐trapping experiments (Figure S12, Supporting Information) have been performed to elucidate the photocatalytic degradation processes of BV‐NP6, 10S/BV‐NP6, and 5Si‐10S/BV‐NP6. EDTA‐2Na, isopropyl alcohol (IPA), and benzoquinone are used to scavenge h + , •OH, and •O 2 − , respectively . When IPA is added to the photocatalytic system, the photoactivity of BV‐NP6 has been obviously decreased, indicating that the photogenerated •OH is dominant in the degradation of 2,4‐DCP.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol

Kang

Chen

et al. 2017

Part & Part Syst Charact

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Bismuth vanadate (BiVO4) is a promising visible‐light responsive photocatalyst, whose photocatalytic activity can be significantly improved by increasing its surface area and utilizing its high‐energy‐level photogenerated electrons effectively. In this work, 2D BiVO4 nanoplates with large specific surface area are successfully fabricated by hydrothermal conversion with the pre‐prepared BiOCl nanosheets as precursors. To improve the photogenerated charge separation, resulted BiVO4 nanoplates are further coupled with nanocrystalline SnO2 to construct heterojunctions, then silicate bridges are introduced between the interfaces of BiVO4 and SnO2. The amount‐optimized silicate‐bridged SnO2/BiVO4 nanocomposite exhibit exceptional visible‐light photocatalytic activities, by ≈7‐time and 4‐time enhancements for CO2 conversion to CH4 and for 2,4‐dichlorophenol degradation, respectively, compared to bare BiVO4 nanoparticles. The significantly enhanced charge separation is verified by steady‐state and time‐resolved surface photovoltage responses and produced hydroxyl radical amounts. Moreover, it is deduced through designed photo‐electrochemical experiments that the introduced SnO2 acts as a proper‐energy platform capable of accepting the photogenerated electrons of BiVO4 nanoplates, and the constructed silicate bridges further facilitate the electron transfer between BiVO4 and SnO2. This work opens up a feasible route to synthesize visible‐light‐driven 2D bismuth‐based nano‐photocatalysts with high photocatalytic activities for efficient fuel production and environmental remediation.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol

Kang

Chen

et al. 2017

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“…The following scavengers were chosen: isopropanol concentration and catalyst loading were 100 ppm and 1.0 g L -1 , respectively. The concentrations of the radical scavengers were 0.20 mM [27]; light irradiance was 1 mW cm -2 .…”

Section: Liquid-phase Photocatalytic Testmentioning

confidence: 99%

Solid-state synthesis, characterization, UV-induced coloration and photocatalytic activity – The Sr6Bi2O11, Sr3Bi2O6 and Sr2Bi2O5 bismuthates

et al. 2020

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This article reports on two novel visible-light-active strontium bismuthate photocatalysts (Sr 6 Bi 2 O 11 and Sr 3 Bi 2 O 6) prepared by solid-state synthesis for which the number of strontium atoms exceeded the number of bismuth atoms in the cation sublattice; for comparison, the bismuthate Sr 2 Bi 2 O 5 was also reexamined. All three bismuthates were characterized by a variety of spectroscopic techniques (XRD, XPS, EDX, DR, Raman, SEM, and EIS). Both newly as-synthesized bismuthates displayed photocatalytic activity toward the photodegradation of substrates in the gas phase (acetaldehyde) and in aqueous media (phenol), with the Sr 6 Bi 2 O 11 phase exhibiting a significantly greater photoactivity than the Sr 3 Bi 2 O 6 phase; by comparison, the bismuthate Sr 2 Bi 2 O 5 was photocatalytically inactive. Detailed photocatalytic mechanisms have been proposed to explain how composition and structure of the three bismuthates affect their photocatalytic activity. The role of point defects in their crystal lattice is described for processes in which the photocatalytic activity was inhibited. Inferences made were aided by examining the UV-induced coloration of these ternary metal oxides that provided information regarding defect levels within their respective bandgaps; such defects acted as electron traps and thus affected the photocatalytic performance of the bismuthates.

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“…The energy was also 8.48 kcal•mol −1 lower than that of Ph-HEH, indicating that the 2e − hydride transfer hydrogenation of the flask is more favorable than that of Ph-HEH. 43 Control experiments in the presence of benzoquinone 44 or TEMPO 45 as radical scavengers caused a significant decrease in the conversion of 1a, reaching 14 and 18%, respectively (Figure 3b). The result confirmed that the photoinduced electron transfer (PET) processes relevant to the excited state of the NAD + mimics are dominant in the in situ regeneration of the NADH mimic active sites.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Metal–Organic Capsules with NADH Mimics as Switchable Selectivity Regulators for Photocatalytic Transfer Hydrogenation

Wei

Zhao

et al. 2019

J. Am. Chem. Soc.

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Switchable selective hydrogenation among the groups in multifunctional compounds is challenging because selective hydrogenation is of great interest in the synthesis of fine chemicals and pharmaceuticals as a result of the importance of key intermediates. Herein, we report a new approach to highly selectively (>99%) reducing CX (X = O, N) over the thermodynamically more favorable nitro groups locating the substrate in a metal−organic capsule containing NADH active sites. Within the capsule, the NADH active sites reduce the double bonds via a typical 2e − hydride transfer hydrogenation, and the formed excited-state NAD + mimics oxidize the reductant via two consecutive 1e − processes to regenerate the NADH active sites under illumination. Outside the capsule, nitro groups are highly selectively reduced through a typical 1e − hydrogenation. By combining photoinduced 1e − transfer regeneration outside the cage, both 1e − and 2e − hydrogenation can be switched controllably by varying the concentrations of the substrates and the redox potential of electron donors. This promising alternative approach, which could proceed under mild reaction conditions and use easy-to-handle hydrogen donors with enhanced high selectivity toward different groups, is based on the localization and differentiation of the 2e − and 1e − hydrogenation pathways inside and outside the capsules, provides a deep comprehension of photocatalytic microscopic reaction processes, and will allow the design and optimization of catalysts. We demonstrate the advantage of this method over typical hydrogenation that involves specific activation via well-modified catalytic sites and present results on the high, well-controlled, and switchable selectivity for the hydrogenation of a variety of substituted and bifunctional aldehydes, ketones, and imines.

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On the question of the optimal concentration of benzoquinone when it is used as a radical scavenger

Cited by 21 publications

References 16 publications

Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol

Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol

Solid-state synthesis, characterization, UV-induced coloration and photocatalytic activity – The Sr6Bi2O11, Sr3Bi2O6 and Sr2Bi2O5 bismuthates

Metal–Organic Capsules with NADH Mimics as Switchable Selectivity Regulators for Photocatalytic Transfer Hydrogenation

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On the question of the optimal concentration of benzoquinone when it is used as a radical scavenger

Cited by 21 publications

References 16 publications

Synthesis of Silicate‐Bridged Heterojunctional SnO2/BiVO4 Nanoplates as Efficient Photocatalysts to Convert CO2 and Degrade 2,4‐Dichlorophenol

Synthesis of Silicate‐Bridged Heterojunctional SnO2/BiVO4 Nanoplates as Efficient Photocatalysts to Convert CO2 and Degrade 2,4‐Dichlorophenol

Solid-state synthesis, characterization, UV-induced coloration and photocatalytic activity – The Sr6Bi2O11, Sr3Bi2O6 and Sr2Bi2O5 bismuthates

Metal–Organic Capsules with NADH Mimics as Switchable Selectivity Regulators for Photocatalytic Transfer Hydrogenation

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Product

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Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol

Synthesis of Silicate‐Bridged Heterojunctional SnO₂/BiVO₄ Nanoplates as Efficient Photocatalysts to Convert CO₂ and Degrade 2,4‐Dichlorophenol