Journal of Materials Chemistry A
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2019
·Vol. 7
·期 10
·5324-5332
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IF 10.733
Mao Wu,Yansheng Gong,Tao Nie,Jin Zhang,Rui Wang,Huanwen Wang,Beibei He
Nanocage-like 3D porous graphitic carbon nitride (g-C3N4) with a high surface area and nitrogen defects was successfully prepared via a novel, template-free, cost-effective and hydrothermal-copolymerization route. Compared with pristine g-C3N4, the synergetic effect of nitrogen vacancies combined with a nanocage-like structure endowed it with a broad visible-light-responsive range, more exposed active lateral edges and catalytically active sites, as well as efficient separation of photogenerated carriers. As a consequence, the modified g-C3N4 exhibited prominent photocatalytic performance in water splitting for the hydrogen evolution reaction under visible light illumination. The optimized photocatalyst (DCN-550) showed a maximum photocatalytic H2 evolution rate of 92.57 μmol h−1, almost 20.3 times higher than that of pristine g-C3N4. Moreover, a possible mechanism for the photocatalytic hydrogen evolution and nanostructure formation process based on the experimental results was proposed. The new growth strategy developed here could inspire similar attempts to modify novel visible-light-driven photocatalysts through nanostructure design.
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Energy Technology
·
2018
·Vol. 7
·期 8
·1800846
·
IF 3.175
Sibo Chen,Siyuan Yang,Xiaolin Sun,Kelin He,Yun Hau Ng,Xin Cai,Wuyi Zhou,Yueping Fang,Shengsen Zhang
The photocatalytic H 2 evolution is an important technology to solve the energy crisis. The hydrogen evolution rate of the graphite carbon nitride (g-C 3 N 4 ) system in triethanolamine solution as sacrificial agent is clearly higher than that in methanol solution. But up to now, most of the Cu nanoparticles as cocatalyst of g-C 3 N 4 photocatalytic systems for hydrogen evolution are performed in methanol solution because Cu nanoparticles are unstable in triethanolamine solution. Here, carbon-coated Cu nanoparticles as a cocatalyst of g-C 3 N 4 composites (Cu@C/g-C 3 N 4 ) are prepared by a simple two-step technology that includes annealing followed by grinding. The compositions, morphology, and optical and photoelectrochemical properties of the composites are characterized by means of physicochemical techniques. The prepared composition is used to generate hydrogen under visible-light irradiation in triethanolamine solution. The results show that the hydrogen evolution rate of the optimal Cu@C/g-C 3 N 4 is up to 265.1 μmol g −1 h −1 , which is close to the activity of 0.5% Pt/g-C 3 N 4 , and after four repeated reactions, the photocatalytic activity decreases only by ≈15%. The good photocatalytic activity and stability result from Cu nanoparticles increase the transfer efficiency of charge carriers by trapping the photogenerated electrons produced by g-C 3 N 4 and the protective effect of carbon layer on Cu nanoparticles.
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MATERIALS CHEMISTRY AND PHYSICS
·
2019
·
IF 2.781
Dongya Li,Yang Xiao,Mengjie Pu,Jie Zan,Shiyu Zuo,Haiming Xu,Dongsheng Xia
The application of sodium percarbonate (SPC) catalyzed by metal-free protonated g-C 3 N 4 under visible light (vis) irradiation was investigated for the first time to stimulate the degradation of methylene blue (MB) and tetracycline hydrochloride (TCH). The catalyst was obtained by using thermal induction polymerization and chemical exfoliation method. The structure and properties of as-synthesized samples were characterized. Moreover, the effects of various factors such as the initial solution pH on MB degradation were also evaluated. Results obtained in the test actively demonstrated that effective degradation of MB was achieved in the protonated g-C 3 N 4 /SPC/Vis system. This system has a wide range of pH application, and the catalyst presents excellent stability. Holes, superoxide anion radical (•O 2 − ) and hydroxyl radical (•OH) were confirmed as the predominant species responsible for MB degradation. The reaction mechanism for MB degradation in the protonated g-C 3 N 4 /SPC/Vis system was proposed according to the characterization of the samples, the free radical quenching tests, and electron paramagnetic resonance (EPR) spectrum analysis.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Lingling Hu,Huanjunwa He,Dehua Xia,Yajing Huang,Jiarong Xu,Haoyue Li,Chun He,Wenjing Yang,Dong Shu,Po Keung Wong
A self-stabilized Z-scheme porous g-C3N4/I3–-containing BiOI ultrathin nanosheets (g-C3N4/I3–-BiOI) heterojunction photocatalyst with I3–/I– redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-C3N4/I3–-BiOI composites were systematically characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, N2 adsorption/desorption, UV–vis diffuse reflectance spectrum, and photoluminescence. The g-C3N4/I3–-BiOI composites, with a heterojunction between porous g-C3N4 and BiOI ultrathin nanosheets, were first applied for the photocatalytic elimination of ppm-leveled CH3SH under light-emitting diode visible light illumination. The g-C3N4/I3–-BiOI heterojunction with 10% g-C3N4 showed a dramatically enhanced photocatalytic activity in the removal of CH3SH compared with pure BiOI and g-C3N4 due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CH3SH over g-C3N4/I3–-BiOI were deeply explored by in situ diffuse reflectance infrared Fourier transform spectroscopy, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, electron spin resonance and Mott–Schottky experiments, it was revealed that the responsible reactive species for catalytic CH3SH composition were h+, •O2–, and 1O2; thus, the g-C3N4/I3–-BiOI heterojunction followed an indirect all-solid state Z-scheme charge-transfer mode with self-stabilized I3–/I– pairs as redox mediator, which could accelerate the separation of photogenerated charge and enhance the redox reaction power of charged carriers simultaneously.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Fengliang Wang,Yiping Feng,Ping Chen,Yingfei Wang,Yuehan Su,Qianxin Zhang,Yongqin Zeng,Zhijie Xie,Haijin Liu,Yang Liu,Wenying Lv,Guoguang Liu
The occurrence of fluoroquinolones (FQs) in the ambient environment has raised serious concerns. In this study, the photocatalytic degradation kinetics and mechanism of ciprofloxacin (CIP) was investigated in ordered mesoporous g-C 3 N 4 (ompg-C 3 N 4 ). Under simulated sunlight irradiation, ompg-C 3 N 4 exhibited a 2.9 fold more rapid reaction for CIP degradation than bulk g-C 3 N 4 . This enhancement may be attributed to the large specific surface area and effective charge separation of ompg-C 3 N 4 . The eradication of CIP followed the Langmuir–Hinshelwood (L–H) kinetics model, and surface reactions played a significant role during the photocatalysis process. Further study of reactive species (RSs) by both ESR technology and RSs scavenging experiments revealed that the superoxide anion radical (O 2 − ) and photohole (h + ) were primarily responsible for the degradation of CIP. Based on the identification of intermediates using liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), and the prediction of reactive sites via Frontier Electron Densities (FEDs), the degradation pathways of CIP were proposed. A comparison of the degradation among FQs revealed that the piperazine moiety showed a dramatic effect on the degradation of FQs during the photocatalysis process. A residual antibiotic activity experiment revealed that ompg-C 3 N 4 provided a very desirable performance for the reduction of antibiotic activity. The sufficient photocatalytic degradation of CIP in ambient water revealed that a sunlight-driven ompg-C 3 N 4 photocatalytic process may be efficiently applied for the remediation of CIP contaminated natural waters.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2018
·
IF 11.698
Yabin Jiang,Zongzhao Sun,Chao Tang,Yuxia Zhou,Lei Zeng,Limin Huang
Porous structure, nitrogen defects and oxygen dopants are simultaneously introduced into the framework of graphitic carbon nitride (g-C 3 N 4 ) by a simple co-pyrolysis of dicyandiamide and ammonium persulphate ((NH 4 ) 2 S 2 O 8 ). The (NH 4 ) 2 S 2 O 8 plays multi-function roles in the co-pyrolysis process. It not only restrains polycondensation to generate nitrogen defects but also introduces porous structure and oxygen dopants due to its strong oxidative ability. The synergetic effect of the nitrogen defects and oxygen dopants leads to the change of π band state and LP state (lone pair electrons), causing the change of electron transition in the modified g-C 3 N 4 . The transitions from impurity levels play a predominant role in excitation process while the transition from intrinsic HOMO to LUMO becomes subordinate, which improve the charge separation significantly. The modified g-C 3 N 4 exhibits excellent photocatalytic hydrogen evolution activity under visible light illumination, which is almost 6 times higher than pristine g-C 3 N 4 because of the improved efficiency of charge separation and increased specific surface area. These findings provide a simple and efficient method to improve the photocatalytic activity of g-C 3 N 4 by changing the electron transition through a rational band structure engineering.
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Journal of CO2 Utilization
·
2018
·
IF 5.503
Qian Li,Zhuxing Sun,Haiqiang Wang,Zhongbiao Wu
In this study, hollow-structured Bi decorated g-C 3 N 4 hybrids were successfully fabricated by a simple solvothermal method and applied for the first time to the photocatalytic reduction of CO 2 . Remarkably, the composites exhibited excellent CO 2 conversion efficiencies in the presence of H 2 O under visible light irradiation compared to unmodified g-C 3 N 4 , especially for the production of CH 4 . The optimum photocatalyst 30-Bi/g-C 3 N 4 presented the best production of CO and CH 4 , approximately 3 times and 9 times as high as those of unmodified g-C 3 N 4 , respectively. A series of characterizations were conducted to explore the essence behind such an enhancement; we found that enhanced light harvesting, quick separation of photoinduced carriers and more negative conduction band, due to the formation of a Schottky junction between g-C 3 N 4 and Bi metal and the solvothermal process, co-contributed for the enhanced CO 2 conversion; A more important finding was that the surprising improvement of CH 4 yield stem primarily from the introduction of the hollow-structured Bi, which enabled the accumulation of electrons on its surface exhibiting the metal-like property. The CO 2 photocatalytic conversion process was also investigated by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) spectroscopy and we found that HCO 3 − and CO 2 − were active intermediates over 30-Bi/g-C 3 N 4 and Bi doping could promote the activation of CO 2 . In summary, this work presented hollow-structured Bi decorated g-C 3 N 4 composites as new materials for energy applications, proving once more the meta-like nature of bismuth, and laying the groundwork for the utilization of Bi in CO 2 photocatalytic reduction processes.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
·
IF 11.698
Zhi Zhu,Xu Tang,Tianshuai Wang,Wenqian Fan,Zhi Liu,Chunxiang Li,Pengwei Huo,Yongsheng Yan
Developing low-cost and high-efficiency g-C 3 N 4 (CN) semiconductor with modification has been proved to possess the potential advantage for environmental remediation in recent years. Herein, element doping of CN framework was found significantly on controlling its electronic structure. The new two-dimensional photocatalyst of Co-doped CN (Co-CN) applicable in photocatalytic reactions for 2-Mercaptobenzothiazole degradation was designed and synthesized. It was for the first time revealed that the Co-N bonding could lead to enhance significantly photoelectric properties, the rate for electron-hole pairs separation and photocatalytic activity in comparison with bulk CN. The characterization and density functional theory (DFT) results insight into the reason that the 3d electrons of the doped Co has excellent contribution to adjust the band gap of Co-CN. The present work provide a broadening window for Metal-doped CN with outstanding performance.
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ANALYTICA CHIMICA ACTA
·
2018
·
IF 5.123
Yanyu Lin,Rongkai Shen,Nannan Liu,Huan Yi,Hong Dai,Jianhua Lin
Here, a simple electrochemical biosensor was proposed based on the specific recognition between trypsin and peptide. Initially, NiCo 2 O 4 -PAMAM nanocomposite was casted on the bare electrode to achieve the electrochemical signal amplification in 0.1 mM [Ru(NH 3 ) 6 ] 3+ solution owing to the great electronic conductivity and high electrochemical activity induced by the special structure of NiCo 2 O 4 nanosheets (Ni 3+ cations in octachedral sites of the Co 3 O 4 ). Subsequently, a declined electrochemical signal was obtained when g-C 3 N 4 labeled peptide composites were anchored on the electrode. However, after trypsin was added into solution and incubated with the biosensor, the electrochemical signal was re-promoted. Therefore, the as-synthesized biosensor could realize the sensitive detection of trypsin by virtue of the specific recognition between trypsin and peptide. As a result, the developed peptide-based exhibited a linear range from 10 −10 to 10 −4 mg mL −1 with an ultralow detection limit of 10 −10 mg mL −1 , providing sensitive analytical performance and acceptable application potential in clinical test and disease diagnosis due to its high stability, excellent selectivity , acceptable reproducibility and accurate signal output.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2018
·
IF 5.091
Jirong Bai,Chaochuang Yin,Haiyang Xu,Gang Chen,Zhijiang Ni,Zhilei Wang,Yaguang Li,Shifei Kang,Zheng Zheng,Xi Li
Hydrogen generation photocatalyzed by low-cost graphite carbon nitride (g-C 3 N 4 ) is a fascinating and effective route to solve energy crisis, but is mainly limited by the few reactive sites, low carrier separation efficiency and mediocre visible-light utilization. In this work, these limitations were tackled through a facile eco-friendly precursor pretreatment by tuning bulk g-C 3 N 4 into porous structure. This pretreatment restricted agglomeration in the subsequent condensation and created more porous channels for charge carrier transfer and more surface active sites for reaction. The modified g-C 3 N 4 has larger surface area, broader visible-light response, enhanced electron migration capacity and prolonged lifetime of photogenerated carriers. These well-amended g-C 3 N 4 nanosheets possess an average hydrogen evolution rate 5.7 times that of bulk g-C 3 N 4 . This work affords a facile, eco-friendly and scalable strategy to design or synthesize other porous materials.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 8
·1-10
·
IF 5.479
Shi Han,Zhang Liang,Yu Guoliang,Liu Yuting,Chen Ligang
A new dual-emission ratiometric fluorescent probe was synthesized and successfully used for the determination of Malachite Green (MG) in fish farming water. The ratiometric fluorescent probe was successfully composited by sol-gel method using C 3 N 4 and CdTe quantum dots as fluorescent materials combined with mesoporous molecularly imprinted polymers. MG quenches the red fluorescence of the CdTe QDs (with excitation/emission wavelengths at 350/680 nm) while the blue fluorescence of C 3 N 4 (with excitation/emission wavelengths at 350/458 nm) remains unchanged. The change of fluorescence color and fluorescence intensity ratio can be successfully used for quantification of malachite green. In addition, the mesoporous structure has a large surface and good adsorption capacity for malachite green. The normalized intensity of fluorescence increases linearly in the 50–1000 ng·mL −1 MG concentration range, and the detection limit is 10 ng·mL −1 . The imprinting factor is 3.2. The nanoprobe was applied to the determination of MG in fish farming water samples. Recoveries and relative standard deviations were 92.5–97.8% and 2.5–6.2%, respectively.
Schematic representation of synthesis of molecularly imprinted mesoporous silica ratiometric fluorescent probes incorporating C 3 N 4 dots and CdTe quantum dots for determination of malachite green.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2017
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IF 5.401
Ya-Ning Wang,Ying Zhang,Wen-Shu Zhang,Zhang-Run Xu
A novel surface-enhanced Raman scattering substrate was developed through in situ growing gold nanoparticles inside the mesoporous graphitic carbon nitride with a large surface area. The mesoporous structure afforded support for loading more gold nanoparticles, defined the nanoparticle diameter and ensured uniform distribution of the nanoparticles. Crystal violet used as a Raman probe was detected by SERS based on the hybrids with an enhancement factor of 5.0 × 10 5 , and the relative standard deviation of the peak intensity (at 1174 cm −1 and 1618 cm −1 ) were 6.2% and 6.1% (n = 30) for solid samples, and 5.1% and 5.0% (n = 11) for liquid samples. The high SERS activity was attributed to abundant hot spots formed by high-density gold nanoparticles and chemical enhancement from mpg-C 3 N 4 , and the good reproducibility was due to controlled size and uniform distribution of the gold nanoparticles. An antineoplastic drug, 6-thioguanine was detected with a wide linear range from 0.60 μM to 48 μM and a low detection limit of 0.24 μM. The mesoporous g-C 3 N 4 embedded with gold nanoparticles significantly improved the SERS sensitivity and reproducibility for 6-thioguanine detection, and it holds promising potential in noninvasive and ultrasensitive drug monitoring.
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