Graphitic carbon nitride embedded with graphene materials towards photocatalysis of bisphenol A: The role of graphene and mediation of superoxide and singlet oxygen

Carbon dots (CDs) and graphitic carbon nitride (g-C3N4) composites (CD/g-C3N4) were successfully synthesized by a hydrothermal method using urea and sugarcane juice as starting materials. The chemical composition, morphological structure and optical properties of the composites and CDs were characterized using various spectroscopic techniques as well as transmission electron microscopy. X-ray photoelectron spectroscopy (XPS) results revealed new signals for carbonyl and carboxyl groups originating from the CDs in CD/g-C3N4 composites while X-ray diffraction (XRD) results showed distortion of the host matrix after incorporating CDs into g-C3N4. Both analyses signified the interaction between g-C3N4 and CDs. The photoluminescence (PL) analysis indicated that the presence of too many CDs will create trap states at the CD/g-C3N4 interface, decelerating the electron (e−) transport. However, the CD/g-C3N4(0.5) composite with the highest coverage of CDs still achieved the best bisphenol A (BPA) degradation rate at 3.87 times higher than that of g-C3N4. Hence, the charge separation efficiency should not be one of the main factors responsible for the enhancement of the photocatalytic activity of CD/g-C3N4. Instead, the light absorption capability was the dominant factor since the photoreactivity correlated well with the ultraviolet–visible diffuse reflectance spectra (UV–vis DRS) results. Although the CDs did not display upconversion photoluminescence (UCPL) properties, the π-conjugated CDs served as a photosensitizer (like organic dyes) to sensitize g-C3N4 and injected electrons to the conduction band (CB) of g-C3N4, resulting in the extended absorption spectrum from the visible to the near-infrared (NIR) region. This extended spectral absorption allows for the generation of more electrons for the enhancement of BPA degradation. It was determined that the reactive radical species responsible for the photocatalytic activity were the superoxide anion radical (O2 •−) and holes (h+) after performing multiple scavenging tests.

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A self-powered sensor based on molecularly imprinted polymer-coupled graphitic carbon nitride photoanode for selective detection of bisphenol A

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2017.12.075 ◽

2018 ◽

Vol 259 ◽

pp. 394-401 ◽

Cited By ~ 25

Author(s):

Kai Yan ◽

Yaohua Yang ◽

Jingdong Zhang

Keyword(s):

Bisphenol A ◽

Molecularly Imprinted Polymer ◽

Carbon Nitride ◽

Graphitic Carbon ◽

Graphitic Carbon Nitride ◽

Selective Detection ◽

Imprinted Polymer ◽

Molecularly Imprinted ◽

Self Powered

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The Role of Graphitic Carbon Nitride in the Formulation of Copper-Free Friction Composites Designed for Automotive Brake Pads

Metals ◽

10.3390/met12010123 ◽

2022 ◽

Vol 12 (1) ◽

pp. 123

Author(s):

Vlastimil Matějka ◽

Mara Leonardi ◽

Petr Praus ◽

Giovanni Straffelini ◽

Stefano Gialanella

Keyword(s):

Carbon Nitride ◽

Room Temperature ◽

Graphitic Carbon ◽

Graphitic Carbon Nitride ◽

Main Role ◽

Brake Pads ◽

Pin On Disc ◽

Brake Lining ◽

Automotive Brake

In this study, graphitic carbon nitride (g-C3N4, labelled as gCN) was tested in the formulation of copper-free (Cu-free) friction mixtures, which are potentially interesting for brake pad manufacturing. Three formulations of friction composites were prepared starting from a common Cu-free master batch: (i) without graphite, (ii) with graphite and (iii) with gCN. The mixtures were pressed in the form of pins by hot-press moulding. The friction-wear performance of the prepared pins was investigated using a pin-on-disc (PoD) test at room temperature (RT), high temperature (HT) (400 °C) and, again, at room temperature (H-RT). The values of the friction coefficient (µ) for the composites with gCN (or graphite) were as follows: (i) RT test, µRT = 0.52 (0.47); (ii) HT test, µHT = 0.37 (0.37); (iii) RT after the HT tests, µH-RT = 0.49 (0.39). With respect to wear resistance, the samples with graphite performed better than the samples without this solid lubricant. To the best of our knowledge, this is the first report regarding the evaluation of the role of gCN in friction composites designed for automotive brake lining applications. The results indicate the main role of gCN as a soft abrasive.

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Few-layer graphitic carbon nitride nanosheet with controllable functionalization as an effective metal-free activator for peroxymonosulfate photocatalytic activation: Role of the energy band bending

Chemical Engineering Journal ◽

10.1016/j.cej.2020.126072 ◽

2020 ◽

Vol 401 ◽

pp. 126072 ◽

Cited By ~ 11

Author(s):

Hai Guo ◽

Huai-Yuan Niu ◽

Chao Liang ◽

Cheng-Gang Niu ◽

Yu Liu ◽

...

Keyword(s):

Energy Band ◽

Carbon Nitride ◽

Graphitic Carbon ◽

Graphitic Carbon Nitride ◽

Band Bending ◽

Metal Free ◽

Energy Band Bending

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Surface-Doped Graphitic Carbon Nitride Catalyzed Photooxidation of Olefins and Dienes: Chemical Evidence for Electron Transfer and Singlet Oxygen Mechanisms

Catalysts ◽

10.3390/catal9080639 ◽

2019 ◽

Vol 9 (8) ◽

pp. 639 ◽

Cited By ~ 3

Author(s):

Apostolos Chatzoudis ◽

Vasileios Giannopoulos ◽

Frank Hollmann ◽

Ioulia Smonou

Keyword(s):

Electron Transfer ◽

Energy Transfer ◽

Singlet Oxygen ◽

Carbon Nitride ◽

Solvent Polarity ◽

Graphitic Carbon ◽

Graphitic Carbon Nitride ◽

Electron Transfer Mechanism ◽

Heterogeneous Nature ◽

Chemical Evidence

A new photocatalytic reactivity of carbon-nanodot-doped graphitic carbon nitride (CD-C3N4) with alkenes and dienes, has been disclosed. We have shown that CD-C3N4 photosensitizes the oxidation of unsaturated substrates in a variety of solvents according to two competing mechanisms: the energy transfer via singlet oxygen (1O2) and/or the electron transfer via superoxide (O·−2). The singlet oxygen, derived by the CD-C3N4 photosensitized process, reacts with alkenes to form allylic hydroperoxides (ene products) whereas with dienes, endoperoxides. When the electron transfer mechanism operates, cleavage products are formed, derived from the corresponding dioxetanes. Which of the two mechanisms will prevail depends on solvent polarity and the particular substrate. The photocatalyst remains stable under the photooxidation conditions, unlike the most conventional photosensitizers, while the heterogeneous nature of CD-C3N4 overcomes usual solubility problems.

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