Selective hydrogen-deuterium exchange in graphitic carbon nitrides: probing the active sites for photocatalytic water splitting by solid-state NMR

2021 ◽  
Author(s):  
Ruidi Wang ◽  
Beibei Xv ◽  
Jiachen Wang ◽  
Xue Lu Wang ◽  
Yefeng Yao
Keyword(s):  
Reaction Mechanisms ◽  
Solid State Nmr ◽  
Active Sites ◽  
Carbon Nitride ◽  
Molecular Level ◽  
Structural Characteristics ◽  
Graphitic Carbon ◽  
Hydrogen Deuterium Exchange ◽  
Hydrogen Deuterium ◽  
Further Development

Graphitic carbon nitride (g-C3N4), the relationships between whose structural characteristics and the photocatalytic reaction mechanisms still remains unclarified at the molecular level, severely hinders the further development of this field....

scholarly journals Influence of Hydrogenation on Morphology, Chemical Structure and Photocatalytic Efficiency of Graphitic Carbon Nitride

2021 ◽  
Vol 22 (23) ◽  
pp. 13096
Author(s):  
Daria Baranowska ◽  
Tomasz Kędzierski ◽  
Małgorzata Aleksandrzak ◽  
Ewa Mijowska ◽  
Beata Zielińska
Keyword(s):  
Photocatalytic Activity ◽  
Active Sites ◽  
Chemical Structure ◽  
Carbon Nitride ◽  
Elevated Temperatures ◽  
Hydrogen Atmosphere ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Efficiency ◽  
Highly Active

In this contribution, the effect of hydrogenation conditions atmosphere (temperature and time) on physicochemical properties and photocatalytic efficiency of graphitic carbon nitride (g-C3N4, gCN) was studied in great details. The changes in the morphology, chemical structure, optical and electrochemical properties were carefully investigated. Interestingly, the as-modified samples exhibited boosted photocatalytic degradation of Rhodamine B (RhB) with the assistance of visible light irradiation. Among modified gCN, the sample annealed at 500 °C for 4 h (500-4) in H2 atmosphere exhibited the highest photocatalytic activity—1.76 times higher compared to pristine gCN. Additionally, this sample presented high stability and durability after four cycles. It was noticed that treating gCN with hydrogen at elevated temperatures caused the creation of nitrogen vacancies on gCN surfaces acting as highly active sites enhancing the specific surface area and improving the mobility of photogenerated charge carriers leading to accelerating the photocatalytic activity. Therefore, it is believed that detailed optimization of thermal treatment in a hydrogen atmosphere is a facile approach to boost the photoactivity of gCN.

Scalable and clean exfoliation of graphitic carbon nitride in NaClO solution: enriched surface active sites for enhanced photocatalytic H2 evolution

2018 ◽  
Vol 20 (6) ◽  
pp. 1354-1361 ◽  
Author(s):  
Lifeng Cui ◽  
Yanfei Liu ◽  
Xueyou Fang ◽  
Chaochuang Yin ◽  
Shasha Li ◽  
...  
Keyword(s):  
Drinking Water ◽  
Active Sites ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
H2 Evolution ◽  
Surface Active ◽  
Photocatalytic H2 Evolution

The challenge of exfoliation of bulk g-C3N4 into nanosheets was tackled using green drinking-water disinfectant NaClO in solution.

Tuning local carbon active sites saturability of graphitic carbon nitride to boost CO2 electroreduction towards CH4

Nano Energy ◽  
2020 ◽  
Vol 73 ◽  
pp. 104833 ◽  
Author(s):  
Zhou Chen ◽  
Min-Rui Gao ◽  
Ya-Qian Zhang ◽  
Nanqi Duan ◽  
Tingting Fan ◽  
...  
Keyword(s):  
Active Sites ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Co2 Electroreduction

scholarly journals Porous g-C3N4 with defects for the efficient Dye photodegradation under visible light

2021 ◽  
Author(s):  
Jing Chen ◽  
Yage Zhang ◽  
Baofan Wu ◽  
Zhichao Ning ◽  
Miaoyan Song ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Methyl Orange ◽  
Visible Light ◽  
Active Sites ◽  
Carbon Nitride ◽  
Narrow Band ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Electron Hole ◽  
High Durability

Abstract Porous graphitic carbon nitride (p-C3N4) was fabricated via simply pyrolyzing treatment of graphitic carbon nitride (g-C3N4). The defects could be introduced into the structure of g-C3N4 by the broken of some bonds, which was beneficial for the generation of electron-hole pairs and restraining their recombination. Compared with g-C3N4, p-C3N4 showed a narrow band gap to promote the utilization of visible light. Furthermore, the porous structure also increased the specific surface area to maximize the exposure of active sites and promote the mass transfer during photodegradation. As a result, the as-reported p-C3N4 exhibited considerably higher degradation efficiency for Rhodamine B (RhB) and Methyl Orange (MO) than that of pristine g-C3N4. Moreover, the photocatalyst showed high durability and stability in recycling experiments.

Hydrogen—deuterium exchange reactions on ion-exchanged X-type zeolites

1971 ◽  
Vol 321 (1545) ◽  
pp. 249-257 ◽  
Keyword(s):  
Active Sites ◽  
Large Range ◽  
Deuterium Exchange ◽  
Water Molecules ◽  
Hydrogen Treatment ◽  
Residual Water ◽  
Hydrogen Deuterium Exchange ◽  
Exchange Reactions ◽  
Hydrogen Deuterium ◽  
Homolytic Dissociation

The hydrogen—deuterium exchange reaction has been studied over a series of X-type zeolites. With CoX zeolites the activity depended linearly on the extent of ion-exchange showing that the Co 2+ ions do not enter preferentially the positions which are likely to be inaccessible to the reacting molecules. Enhanced activity was found after hydrogen treatment of CoX at 200 °C or CaX and MnX at 300 °C and to a lesser extent at temperatures about 50 K lower. This increase in activity was thought to arise from the displacement of water molecules from the active sites by chemisorbed hydrogen. Other evidence for the poisoning effects of residual water was obtained from the variation in the activity of a CoX zeolite with outgassing temperature. There was no correlation between activity and charge on the metal ions—CeX was only slightly more active than NaX and there was a large range in the activity of the zeolites containing different divalent ions (Ni ⪢ Zn > Co > Mn > Ca). It is possible that NiX, the only catalyst giving high rates below 0 °C, brings about the exchange by a mechanism involving the homolytic dissociation of hydrogen. The results show that the usefulness of deuterium for the study of the exchange reactions with hydrocarbons may be limited to a few of the more active zeolites such as NiX and possibly ZnX or CoX.

Unexpected monoatomic catalytic-host synergetic OER/ORR by graphitic carbon nitride: density functional theory

Nanoscale ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 5064-5071 ◽  
Author(s):  
Yong Wu ◽  
Can Li ◽  
Wei Liu ◽  
Huanhuan Li ◽  
Yinyan Gong ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Active Sites ◽  
Density Functional ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Single Atom ◽  
Functional Theory ◽  
Metal Atoms

Although single metal atoms (SMAs) have been extensively investigated as unique active sites in single-atom catalysts, the possible active sites of the host catalysts have been unfortunately neglected in previous studies.

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