Magnetically recoverable Fe3O4/g-C3N4 composite for photocatalytic production of benzaldehyde under UV-LED radiation

Lima, Mário; Sampaio, Maria J.; Silva, Cláudia G.; Silva, Adrián M.T.; Faria, Joaquim L.

doi:10.1016/j.cattod.2018.11.018

Cited by 46 publications

(23 citation statements)

References 40 publications

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“…In this context, polymeric carbon nitride (PCN), an organic semiconductor possessing a low valence band potential insufficient to directly oxidise water molecule producing • OH, [20] was successfully used for partial heterogeneous photo-oxidation of aromatic alcohols [21][22][23][24][25][26][27][28][29] achieving high yields of aldehydes while using water as solvent. [30,31] Although -H, -OCH3, -CH3, -Cl, -NO2 and -F substituted benzyl alcohols were converted to the corresponding aldehydes by PCN with a nearly 100 % selectivity, [31,32] the attempts with some other molecules like piperonyl alcohol and 5hydroxymethyl furfural (HMF) showed worse results. [31,33] The non-condensed -NH and/or -NH2 species in PCN were suggested to be responsible for the unselective oxidation of HMF.…”

Section: Introductionmentioning

confidence: 99%

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

et al. 2019

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Photocatalysis is an environmentally-friendly and energyefficient mean of selective oxidation of aromatic alcohols to the corresponding aldehydes. In the present work we scrutinized the effect of benzyl alcohol phenyl ring substituents on its aqueousphase photo-oxidation driven by polymeric carbon nitride (PCN) catalyst. It has been established that for the case of benzyl alcohols, electron donating (ED) substituents in para-and ortho-position with respect to the CH2OH-group promote the reactivity of the substrate without compromising the selectivity towards benzaldehydes formation, maintaining it in the range of 84-98 %, if compared to the unsubstituted molecule. The same observation is true for metasubstituted benzyl alcohol with an electron withdrawing (EW) group. On the other hand, the presence of ED-group in meta-position or EW-group in para-position with respect to the benzylic carbon reduces the reactivity as well as the selectivity towards the aldehyde production, resulting in the values of selectivity ranging from 40 to 80 %. The analyses of the experimental data and quantum chemical computational studies of "substrate-catalyst" complexes have established that the reactivity is inversely proportional to the positive charge on the benzylic carbon in benzyl alcohol cation intermediate, while the selectivity correlates with a negative charge on the carbon atoms in the phenyl ring. The ED substituents in meta-and the EW ones in para-position induce a negative charge on one of the carbons in the phenyl ring, making it susceptible for an attack of electrophilic species such as photo-generated holes or • OH radicals, when the substrate is interacting with the carbon nitride noncondensed NH2-groups. The modification of the PCN photocatalyst with H2O2 creates a charge recombination center or a steric hindrance on the NH2-moieties complicating the reactions of oxidative species with the phenyl ring, thus increasing the selectivity towards the corresponding aldehyde production.

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Section: Introductionmentioning

confidence: 99%

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

et al. 2019

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“…Metal oxides are widely used as main catalyst, promoted and support, and then, the synthesis of composite materials of metal oxides and carbon nitride, such as TiO 2 /g‐C 3 N 4 , [101] ZnO/g‐C 3 N 4 , [102] Cu 2 O/g‐C 3 N 4 , [103] Fe 3 O 4 /g‐C 3 N 4 [104] and Sn 3 O 4 /g‐C 3 N 4 [105] has been widely studied. The modification of metal oxides can effectively separate the photo generated electrons and holes in the raw material, improve the efficiency of photoelectric conversion, and then improve the performance of the catalyst.…”

Section: Composites Of Metal Oxide and G‐c3n4mentioning

confidence: 99%

Application of g‐C₃N₄ Matrix Composites Photocatalytic Performance from Degradation of Antibiotics

Niu

Wang

et al. 2020

ChemistrySelect

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Semiconductor photocatalysts have broad prospects in the removal of antibiotics in water. In numerous semiconductor light catalyst materials, g‐C3N4 has attracted much attention because of its suitable band gap, high thermal and chemical stability. But its conductivity is poor, and the visible light utilization rate is low, which restrict the range of application. Modification strategies such as doping and semiconductor materials compounding can expand the visible light absorption range and maintain the advantages of high redox capacity of the photocatalyst. This article introduces the hazards of antibiotics in water, describes the progress of research on the modification of g‐C3N4 by metal elements, non‐metal elements, metal oxides and metal sulfides to remove antibiotics (TCs, SAs etc.) in water. Finally, we try to put forward some new research directions on the basis of the current research of photocatalyst, and put forward some simple views on the application of g‐C3N4.

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“…Consequently, the high catalyst reuse. Redrawn from Lima et al [178] crystallinity of the photocatalyst increases charge delocalization, which can cause photogenerated charge separation and boost redox reactions. Hence, the thermal annealing of photocatalysts can be followed by a melt-salt treatment to improve the crystalline morphology of the photocatalyst.…”

Section: S C H E M E 4 Product Distribution For the Selective Oxidatimentioning

confidence: 99%

“…Some common methods include immobilization on reactor walls, [171,172] immobilization in suitable inert matrices, [173][174][175] or making magnetically separable nanocomposites with photocatalysts. [176,177] For the latter, a magnetically recoverable g-C 3 N 4 was prepared by Lima et al [178] for the photocatalytic conversion of benzyl alcohol to benzaldehyde under UV irradiation. [179] Bulk C 3 N 4 was prepared by thermal deposition followed by intercalation using FeCl 3 .6H 2 O and FeCl 2 .6H 2 O to produce Fe 3 O 4 /g-C 3 N 4 , which had a remarkably lower bandgap of 1.58 eV than pristine g-C 3 N 4 at 2.76 eV.…”

Section: S C H E M E 4 Product Distribution For the Selective Oxidatimentioning

confidence: 99%

High‐performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

Rangarajan

Yan

2020

Can J Chem Eng

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With an increase in awareness about the need for green chemistry, there is a shift in focus towards identifying eco-compatible technologies that can improve product yield and eliminate the use or generation of hazardous compounds. An immediate practical example of such an approach is the development of sustainable methods for alcohol oxidation as alternatives to the current processes that are energy intensive and rely on ecotoxic chemicals. In this regard, heterogeneous photocatalysis has been identified as a robust technique to catalyze reactions under benign conditions, which would otherwise require harsh synthesis routes. With the advent of materials sciences and nanotechnology, there has been a tremendous increase in the scope of applicability of photocatalysis in fine chemicals synthesis. Though an attractive choice, much of the fundamental information pertaining to catalyst activity, selectivity and reaction conditions for optimum conversion are still to be investigated for most of these systems. To this end, this review will encompass recent achievements in the selective photocatalytic oxidation of alcohols by harnessing solar radiation as a viable source of energy. The discussion will be arranged based on common types of photocatalysts reported in literature, namely metal oxides (eg, TiO 2 and ZnO, Nb 2 O 5), sulphides (eg, CdS, CuS, and Bi 2 S 3), and carbonaceous photocatalysts (eg, g-C 3 N 4). Several such candidates for photocatalysts will be discussed critically with the aim of providing useful insight into developing selective photocatalysts that can oxidize alcohols via eco-friendly pathways along with high yields.

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Magnetically recoverable Fe3O4/g-C3N4 composite for photocatalytic production of benzaldehyde under UV-LED radiation

Cited by 46 publications

References 40 publications

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

Application of g‐C₃N₄ Matrix Composites Photocatalytic Performance from Degradation of Antibiotics

High‐performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

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Magnetically recoverable Fe3O4/g-C3N4 composite for photocatalytic production of benzaldehyde under UV-LED radiation

Cited by 46 publications

References 40 publications

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C3N4

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C3N4

Application of g‐C3N4 Matrix Composites Photocatalytic Performance from Degradation of Antibiotics

High‐performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

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Product

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Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

Effect of Substituents on Partial Photocatalytic Oxidation of Aromatic Alcohols Assisted by Polymeric C₃N₄

Application of g‐C₃N₄ Matrix Composites Photocatalytic Performance from Degradation of Antibiotics