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Huiming Cheng - One of the best experts on this subject based on the ideXlab platform.
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nitrogen vacancy promoted photocatalytic activity of Graphitic Carbon Nitride
Journal of Physical Chemistry C, 2012Co-Authors: Ping Niu, Gang Liu, Huiming ChengAbstract:Vacancy defects can play an important role in modifying the electronic structure and the properties of photoexcited charge carriers and consequently the photocatalytic activity of semiconductor photocatalysts. By controlling the polycondensation temperature of a dicyandiamide precursor in the preparation of Graphitic Carbon Nitride (g-C3N4), we introduced nitrogen vacancies in the framework of g-C3N4. These vacancies exert remarkable effects on modifying the electronic structure of g-C3N4 as shown in UV–visible absorption spectra and valence band spectra. Steady and time-resolved fluorescence emission spectra show that, due to the existence of abundant nitrogen vacancies, the intrinsic radiative recombination of electrons and holes in g-C3N4 is greatly restrained, and the population of short-lived and long-lived charge carriers is decreased and increased, respectively. As a consequence, the overall photocatalytic activity of the g-C3N4, characterized by the ability to generate •OH radicals, photodecomposi...
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nitrogen vacancy promoted photocatalytic activity of Graphitic Carbon Nitride
Journal of Physical Chemistry C, 2012Co-Authors: Ping Niu, Gang Liu, Huiming ChengAbstract:Vacancy defects can play an important role in modifying the electronic structure and the properties of photoexcited charge carriers and consequently the photocatalytic activity of semiconductor photocatalysts. By controlling the polycondensation temperature of a dicyandiamide precursor in the preparation of Graphitic Carbon Nitride (g-C3N4), we introduced nitrogen vacancies in the framework of g-C3N4. These vacancies exert remarkable effects on modifying the electronic structure of g-C3N4 as shown in UV-visible absorption spectra and valence band spectra. Steady and time-resolved fluorescence emission spectra show that, due to the existence of abundant nitrogen vacancies, the intrinsic radiative recombination of electrons and holes in g-C3N4 is greatly restrained, and the population of short-lived and long-lived charge carriers is decreased and increased, respectively. As a consequence, the overall photocatalytic activity of the g-C3N4, characterized by the ability to generate center dot OH radicals, photodecomposition of Rhodamine B, and photocatalytic hydrogen evolution under both UV-visible and visible light, was remarkably improved.
Xinchen Wang - One of the best experts on this subject based on the ideXlab platform.
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surface engineering of Graphitic Carbon Nitride polymers with cocatalysts for photocatalytic overall water splitting
Chemical Science, 2017Co-Authors: Guigang Zhang, Xinchen WangAbstract:Graphitic Carbon Nitride based polymers, being metal-free, accessible, environmentally benign and sustainable, have been widely investigated for artificial photosynthesis in recent years for the photocatalytic splitting of water to produce hydrogen fuel. However, the photocatalytic stoichiometric splitting of pure water into H2 and O2 with a molecular ratio of 2 : 1 is far from easy, and is usually hindered by the huge activation energy barrier and sluggish surface redox reaction kinetics. Herein, we provide a concise overview of cocatalyst modified Graphitic Carbon Nitride based photocatalysts, with our main focus on the modulation of the water splitting redox reaction kinetics. We believe that a timely and concise review on this promising but challenging research topic will certainly be beneficial for general readers and researchers in order to better understand the property–activity relationship towards overall water splitting, which could also trigger the development of new organic architectures for photocatalytic overall water splitting through the rational control of surface chemistry.
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invisible security ink based on water soluble Graphitic Carbon Nitride quantum dots
Angewandte Chemie, 2016Co-Authors: Zhiping Song, Xinchen Wang, Tianran Lin, Lihua Lin, Sen Lin, Liangqia GuoAbstract:Stimuli-responsive photoluminescent (PL) materials have been widely used as fluorescent ink for data security applications. However, traditional fluorescent inks are limited in maintaining the secrecy of information because the inks are usually visible by naked eyes either under ambient light or UV-light illumination. Here, we introduced metal-free water-soluble Graphitic Carbon Nitride quantum dots (g-CNQDs) as invisible security ink for information coding, encryption, and decryption. The information written by the g-CNQDs is invisible in ambient light and UV light, but it can be readable by a fluorescence microplate reader. Moreover, the information can be encrypted and decrypted by using oxalic acid and sodium biCarbonate as encryption reagent and decryption reagent, respectively. Our findings provide new opportunities for high-level information coding and protection by using water-soluble g-CNQDs as invisible security ink.
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Graphitic Carbon Nitride polymers toward sustainable photoredox catalysis
Angewandte Chemie, 2015Co-Authors: Yun Zheng, Bo Wang, Xinchen WangAbstract:: As a promising two-dimensional conjugated polymer, Graphitic Carbon Nitride (g-C3 N4 ) has been utilized as a low-cost, robust, metal-free, and visible-light-active photocatalyst in the field of solar energy conversion. This Review mainly describes the latest advances in g-C3 N4 photocatalysts for water splitting. Their application in CO2 conversion, organosynthesis, and environmental purification is also briefly discussed. The methods to modify the electronic structure, nanostructure, crystal structure, and heterostructure of g-C3 N4 , together with correlations between its structure and performance are illustrated. Perspectives on the challenges and opportunities for the future exploration of g-C3 N4 photocatalysts are provided. This Review will promote the utilization of g-C3 N4 materials in the fields of photocatalysis, energy conversion, environmental remediation, and sensors.
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photochemical reduction of co2 by Graphitic Carbon Nitride polymers
ACS Sustainable Chemistry & Engineering, 2014Co-Authors: Jinliang Lin, Zhiming Pan, Xinchen WangAbstract:The combination of cobalt redox catalysis and Carbon Nitride photocatalysis to construct a cascade photoreaction system has been developed for the deoxygenative reduction of CO2 to CO with visible light. The Graphitic Carbon Nitride has been demonstrated to function both as a capture/activation substrate of CO2 and a photocatalyst, whereas the introduced cobalt species act as reductive and oxidative promoters to accelerate charge-carrier separation and transfer kinetics. This hybrid photosystem contains inexpensive substances that synergetically catalyze CO2-to-CO conversion at mild conditions, with a high stability of catalysts. The optimization in the surface and texture structures as well as reaction conditions has been demonstrated. The results represent an important step toward artificial photosynthesis by using cost-acceptable materials.
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exfoliated Graphitic Carbon Nitride nanosheets as efficient catalysts for hydrogen evolution under visible light
Advanced Materials, 2013Co-Authors: Shubin Yang, Xinchen Wang, Jinshui Zhang, Yongji Gong, Liang Zhan, Zheyu Fang, Robert Vajtai, Pulickel M AjayanAbstract:Graphitic Carbon Nitride nanosheets are extracted, produced via simple liquid-phase exfoliation of a layered bulk material, g-C3N4. The resulting nanosheets, having ≈2 nm thickness and N/C atomic ratio of 1.31, show an optical bandgap of 2.65 eV. The Carbon Nitride nanosheets are demonstrated to exhibit excellent photocatalytic activity for hydrogen evolution under visible light.
Ping Niu - One of the best experts on this subject based on the ideXlab platform.
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Photocatalytic overall water splitting by Graphitic Carbon Nitride
'Wiley', 2021Co-Authors: Ping Niu, Junjing Dai, Xiaojuan Zhi, Zhonghui Xia, Shulan WangAbstract:Abstract Photocatalytic overall water splitting (OWS) without using any sacrificial reagent to realize H2 and O2 production in the stoichiometric ratio of 2:1 is viewed as the “holy grail” in the field of solar fuel production. Developing stable, low cost, and nontoxic photocatalysts that have satisfactory solar‐to‐hydrogen conversion efficiency is of significance but challenging for realizing the large‐scale use of this sustainable technology. Among various photocatalysts, Graphitic Carbon Nitride (GCN) has shown great potential as an ideal candidate to fulfill the breakthrough in this dynamic research field due to its attractive physicochemical properties. Herein, for the first time, the state‐of‐the‐art research progress of GCN for photocatalytic OWS is reviewed. We first summarize the basic principle of photocatalytic OWS along with the advantages/challenges of GCN introduced. The strategies that have been used to modulate the OWS activity of GCN are then reviewed, including cocatalyst investigation, morphology modulation, atomic structure modification, crystallinity engineering, and heterostructure construction. Toward the end of the review, the concluding remarks and perspectives for the future development are presented, with our expectation to provide some new ideas for the design of advanced OWS photocatalysts
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nitrogen vacancy promoted photocatalytic activity of Graphitic Carbon Nitride
Journal of Physical Chemistry C, 2012Co-Authors: Ping Niu, Gang Liu, Huiming ChengAbstract:Vacancy defects can play an important role in modifying the electronic structure and the properties of photoexcited charge carriers and consequently the photocatalytic activity of semiconductor photocatalysts. By controlling the polycondensation temperature of a dicyandiamide precursor in the preparation of Graphitic Carbon Nitride (g-C3N4), we introduced nitrogen vacancies in the framework of g-C3N4. These vacancies exert remarkable effects on modifying the electronic structure of g-C3N4 as shown in UV–visible absorption spectra and valence band spectra. Steady and time-resolved fluorescence emission spectra show that, due to the existence of abundant nitrogen vacancies, the intrinsic radiative recombination of electrons and holes in g-C3N4 is greatly restrained, and the population of short-lived and long-lived charge carriers is decreased and increased, respectively. As a consequence, the overall photocatalytic activity of the g-C3N4, characterized by the ability to generate •OH radicals, photodecomposi...
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nitrogen vacancy promoted photocatalytic activity of Graphitic Carbon Nitride
Journal of Physical Chemistry C, 2012Co-Authors: Ping Niu, Gang Liu, Huiming ChengAbstract:Vacancy defects can play an important role in modifying the electronic structure and the properties of photoexcited charge carriers and consequently the photocatalytic activity of semiconductor photocatalysts. By controlling the polycondensation temperature of a dicyandiamide precursor in the preparation of Graphitic Carbon Nitride (g-C3N4), we introduced nitrogen vacancies in the framework of g-C3N4. These vacancies exert remarkable effects on modifying the electronic structure of g-C3N4 as shown in UV-visible absorption spectra and valence band spectra. Steady and time-resolved fluorescence emission spectra show that, due to the existence of abundant nitrogen vacancies, the intrinsic radiative recombination of electrons and holes in g-C3N4 is greatly restrained, and the population of short-lived and long-lived charge carriers is decreased and increased, respectively. As a consequence, the overall photocatalytic activity of the g-C3N4, characterized by the ability to generate center dot OH radicals, photodecomposition of Rhodamine B, and photocatalytic hydrogen evolution under both UV-visible and visible light, was remarkably improved.
Tierui Zhang - One of the best experts on this subject based on the ideXlab platform.
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supramolecular precursor strategy for the synthesis of holey Graphitic Carbon Nitride nanotubes with enhanced photocatalytic hydrogen evolution performance
Nano Research, 2019Co-Authors: Xiaoshuai Wang, Chao Zhou, Run Shi, Qinqin Liu, Geoffrey I N Waterhouse, Chenho Tung, Tierui ZhangAbstract:A simple one-step thermal polymerization method was developed for synthesis of holey Graphitic Carbon Nitride nanotubes, involving direct heating of mixtures of melamine and urea or melamine and cyanuric acid in specific mass ratios. Supramolecular structures formed between the precursor molecules guided nanotube formation. The porous and nanotubular structure of the nanotubes facilitated efficient charge carrier migration and separation, thereby enhancing photocatalytic H2 production in 20 vol.% lactic acid under visible light irradiation. Nanotubes synthesized using melamine and urea in a 1:10 mass ratio (denoted herein as CN-MU nanotubes) exhibited a photocatalytic hydrogen production rate of 1,073.6 μmol·h−1·g−1 with Pt as the cocatalyst, a rate of 4.7 and 3.1 times higher than traditional Pt/g-C3N4 photocatalysts prepared from Graphitic Carbon Nitride (g-C3N4) obtained by direct thermal polymerization of melamine or urea, respectively. On the basis of their outstanding performance for photocatalytic H2 production, it is envisaged that the holey g-C3N4 nanotubes will find widespread uptake in other areas, including photocatalytic CO2 reduction, dye-sensitized solar cells and photoelectrochemical sensors.
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alkali assisted synthesis of nitrogen deficient Graphitic Carbon Nitride with tunable band structures for efficient visible light driven hydrogen evolution
Advanced Materials, 2017Co-Authors: Run Shi, Chao Zhou, Geoffrey I N Waterhouse, Chenho Tung, Yunxuan Zhao, Tong Bian, Yufei Zhao, Tierui ZhangAbstract:A facile synthetic strategy for nitrogen-deficient Graphitic Carbon Nitride (g-C3 Nx ) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea. In situ introduced nitrogen vacancies significantly redshift the absorption edge of g-C3 Nx , with the defect concentration depending on the alkali to nitrogen precursor ratio. The g-C3 Nx products show superior visible-light photocatalytic performance compared to pristine g-C3 N4 .
Hou Wang - One of the best experts on this subject based on the ideXlab platform.
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doping of Graphitic Carbon Nitride for photocatalysis a reveiw
Applied Catalysis B-environmental, 2017Co-Authors: Longbo Jiang, Xingzhong Yuan, Yang Pan, Jie Liang, Guangming Zeng, Hou WangAbstract:Abstract As a fascinating conjugated polymer, Graphitic Carbon Nitride (g-C3N4) has been the hotspot in the materials science as a metal-free and visible-light-responsive photocatalyst. Pure g-C3N4 suffers from the insufficient sunlight absorption, low surface area and the fast recombination of photo-induced electron-hole pairs, resulting in low photocatalytic activity. Element doping is known to be an efficient method to tune the unique electronic structure and band gap of g-C3N4, which considerably broaden the light responsive range and enhance the charge separation. This review summarizes the recent progress in the development of efficient and low cost doped g-C3N4 systems in various realms such as photocatalytic hydrogen evolution, reduction of Carbon dioxide, photocatalytic removal of contaminants in wastewater and gas phase. Typically, metal doping, nonmetal doping, co-doping and heterojunction based on doped g-C3N4 have been explored to simultaneously tune the crystallographic, textural and electronic structures for improving photocatalytic activity by enhancing the light absorption, facilitating the charge separation and transportation and prolonging the charge carrier lifetime. Finally, the current challenges and the crucial issues of element doped g-C3N4 photocatalysts that need to be addressed in future research are presented. This review presented herein can pave a novel avenue and add invaluable knowledge to the family of element doped g-C3N4 for the develop of more effective visible-light-driven photocatalysts.
