The presence and effect of oxygen in graphitic carbon nitride synthetized in air and nitrogen atmosphere

Praus, Petr; Smýkalová, Aneta; Foniok, Kryštof; Matějka, Vlastimil; Kormunda, Martin; Smetana, Bedřich; Cvejn, Daniel

doi:10.1016/j.apsusc.2020.147086

Cited by 27 publications

(28 citation statements)

References 50 publications

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“…Similar with previous studies ( Praus et al, 2020 ; Lin et al, 2021 ) that reported the presence of hydroxyl groups on the CN sheets, oxygen was found in all samples (EDX mapping images). Oxygen-containing CN materials have shown high activity in photocatalytic hydrogen evolution ( Huang et al, 2020 ) and photocatalytic dye degradation ( Praus et al, 2020 ). On the other hand, the bulk concentrations of metal (s) in the samples were quantified by the ICP-OES technique and are reported in Table 1 .…”

Section: Resultssupporting

confidence: 91%

“…The images indicate the presence of very low levels of metal incorporation on the surface of all samples, while XPS spectra ( Supplementary Figure S1 ) indicate that the surface concentrations of metals could be lower than XPS detection limits. Similar with previous studies ( Praus et al, 2020 ; Lin et al, 2021 ) that reported the presence of hydroxyl groups on the CN sheets, oxygen was found in all samples (EDX mapping images). Oxygen-containing CN materials have shown high activity in photocatalytic hydrogen evolution ( Huang et al, 2020 ) and photocatalytic dye degradation ( Praus et al, 2020 ).…”

Section: Resultssupporting

confidence: 91%

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The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide

et al. 2022

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Metal-doped graphitic carbon nitride (MCN) materials have shown great promise as effective photocatalysts for the conversion of acetic acid to carbon dioxide under UV–visible irradiation and are superior to pristine carbon nitride (g-C3N4, CN). In this study, the effects of metal dopants on the physicochemical properties of metal-doped CN samples (Fe-, Cu-, Zn-, FeCu-, FeZn-, and CuZn-doped CN) and their catalytic activity in the photooxidation of acetic acid were investigated and discussed for their correlation, especially on their surface and bulk structures. The materials in the order of highest to lowest photocatalytic activity are FeZn_CN, FeCu_CN, Fe_CN, and Cu_CN (rates of CO2 evolution higher than for CN), followed by Zn_CN, CuZn_CN, and CN (rates of CO2 evolution lower than CN). Although Fe doping resulted in the extension of the light absorption range, incorporation of metals did not significantly alter the crystalline phase, morphology, and specific surface area of the CN materials. However, the extension of light absorption into the visible region on Fe doping did not provide a suitable explanation for the increase in photocatalytic efficiency. To further understand this issue, the materials were analyzed using two complementary techniques, reversed double-beam photoacoustic spectroscopy (RDB-PAS) and electron spin resonance spectroscopy (ESR). The FeZn_CN, with the highest electron trap density between 2.95 and 3.00 eV, afforded the highest rate of CO2 evolution from acetic acid photodecomposition. All Fe-incorporated CN materials and Cu-CN reported herein can be categorized as high activity catalysts according to the rates of CO2 evolution obtained, higher than 0.15 μmol/min−1, or >1.5 times higher than that of pristine CN. Results from this research are suggestive of a correlation between the rate of CO2 evolution via photocatalytic oxidation of acetic acid with the threshold number of free unpaired electrons in CN-based materials and high electron trap density (between 2.95 and 3.00 eV).

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 91%

The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide

et al. 2022

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“…It implies that hydrogen peroxide brought more or less additional oxygen into the GCN structures. The content of carbon and nitrogen can be reduced by decarboxylation [ 30 ] and the removal of amino groups [ 31 ], respectively, as a result of the treatment.…”

Section: Resultsmentioning

confidence: 99%

Modification of Graphitic Carbon Nitride with Hydrogen Peroxide

et al. 2020

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Graphitic carbon nitride (GCN) was synthetized by heating melamine and then it was thermally exfoliated for 1–3 h in air. Both bulk and exfoliated GCN nanomaterials were treated in the 10–30% aqueous solutions of H2O2 for us to study their modification. The light absorption properties were observed by the reddish color and the red-shifts of their UV-Vis spectra. The content of oxygen increased and hydrogen peroxide was supposed to partially oxidize C-OH groups to C=O ones and to form C-O-C groups instead of edge C-NH-C ones. The GCN structure changes were not observed. However, a surface modification of the GCN materials was recognized by their changed photocatalytic activities tested by means of Acid Orange 7 (AO7) and Rhodamines B (RhB), zeta-potentials, and neutralization titration curves.

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“…The remarkable decrease of the oxygen content between MCA and CN-MCA is given by dehydroxylation during the MCA heating. Oxygen in CN-M exists due to oxidation during the melamine heating in air [ 38 ]. The contents of nitrogen and hydrogen in CN-MCA were only a little higher, likely to be due to their dihydroxylation, which is also the reason why the C/N values of both materials were only a little different.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Graphitic Carbon Nitrides Synthetized from Melamine and Melamine-Cyanurate Complex: Characterization and Photocatalytic Decomposition of Ofloxacin and Ampicillin

2021

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Graphitic carbon nitride (g-C3N4, hereafter abbreviated as CN) was prepared by the heating of melamine (CN-M) and melamine-cyanurate complex (CN-MCA), respectively, in air at 550 °C for 4 h. The specific surface area (SSA) of CN-M and CN-MCA was 12 m2 g−1 and 225 m2g−1 and the content of oxygen was 0.62 wt.% and 1.88 wt.%, respectively. The band gap energy (Eg) of CN-M was 2.64 eV and Eg of CN-MCA was 2.73 eV. The photocatalytic activity of the CN materials was tested by means of the decomposition of antibiotics ofloxacin and ampicillin under LED irradiation of 420 nm. The activity of CN-MCA was higher due to its high SSA, which was determined based on the physisorption of nitrogen. Ofloxacin was decomposed more efficiently than ampicillin in the presence of both photocatalysts.

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The presence and effect of oxygen in graphitic carbon nitride synthetized in air and nitrogen atmosphere

Cited by 27 publications

References 50 publications

The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide

The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide

Modification of Graphitic Carbon Nitride with Hydrogen Peroxide

Comparison of Graphitic Carbon Nitrides Synthetized from Melamine and Melamine-Cyanurate Complex: Characterization and Photocatalytic Decomposition of Ofloxacin and Ampicillin

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