OPTICAL MATERIALS
·
2022
·
IF 3.754
Zhengdong Zhang,Xingyu Chen,Shanhua Chen,Qi Dong,Xinyi Zhang,Ao Jiang,Dafu Zhang,Yuli Di,Taishan Li
A Z-scheme TiO 2 /g-C 3 N 4 heterostructure system was used to activate peroxymonosulfate (PMS) for the photocatalytic degradation of Rhodamine B (RhB). The Z-scheme TiO 2 /g-C 3 N 4 heterojunction photocatalysts were successfully synthesized by using a simple impregnation method. The structure and surface morphology of the samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical and electrochemical properties were characterized by UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) electrochemical impedance spectroscopy (EIS).The results indicated that the Z-scheme heterojunction between TiO 2 and g-C 3 N 4 was successful established and the optimal photocatalytic activity was achieved when the mass ratio of TiO 2 to g-C 3 N 4 is 10:1. The degradation rate of RhB (20 mg/L, 50 mL) was 82.79% within 120 min simulated sunlight irradiation. After adding PMS to 10% TiO 2 /g-C 3 N 4 heterojunction photocatalysts , the reaction rate constant (k) of the TiO 2 /g-C 3 N 4 -PMS system is about 11.39 times as large as that with 10% TiO 2 /g-C 3 N 4 system. Moreover, the free radical trapping experiments results demonstrated that h + and SO 4 − · were the main active species in the TiO 2 /g-C 3 N 4 -PMS system.
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 30
·期 16
·15267-15276
·
IF 2.195
Zhang Qingji,Jing Jiangping,Chen Zhuoyuan,Sun Mengmeng,Li Jiarun,Li Yan,Xu Likun
g-C 3 N 4 is a promising material for the application in the area of photoelectrochemical cathodic protection. However, it suffers from limited light absorption and lower charge separation efficiency. In this work, a N defects and C deposition co-modified g-C 3 N 4 , C–g-C 3 N x , was prepared by NaOH-assisted sintering and ethanol-assisted hydrothermal treatment. The presence of N defects and C deposition was verified by the XRD, SEM and XPS tests. The N defects changed the band structure of g-C 3 N 4 by lowering down the conduction band position, therefore widening the light absorption range of g-C 3 N 4 . In addition, the N defects and C deposition co-modification promotes the charge transfer process of g-C 3 N 4 , leading to increased separation efficiency of the photogenerated charge carriers. Therefore, C–g-C 3 N x shows enhanced photoelectrochemical cathodic protection performance for the coupled 316L stainless steel. It can provide a photoinduced potential drop of 120 mV and a photoinduced current density of 9.1 μA cm −2 , which is three times that of pristine g-C 3 N 4 .
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Shuhui Liang,Manman He,Jingjing Guo,Jie Yue,Xipeng Pu,Bo Ge,Wenzhi Li
The BiOBr:Yb 3+ ,Er 3+ /g-C 3 N 4 (BYE/CN) p-n junction photocatalysts were successfully fabricated by a stepwise method. Experimental results show that Er 3+ /Yb 3+ were successfully doped into BiOBr lattice. As-obtained BYE/CN exhibited strong NIR light absorption and upconversion emission from NIR to UV–visible due to the upconversion transition of Er 3+ . The p-n junction was constructed due to the appropriate alignment band structure of BYE and g-C 3 N 4 , which distinctly suppresses the recombination rate of electron-hole pairs. Compared with pure BYE and CN, as-synthesized BYE/CN samples exhibit distinctly improved photoactivities under the irradiation of visible or NIR light, which can be attributed to the upconversion effect of Er 3+ and the construction of p-n junction. This result may provides a promising system for efficient harvest of the NIR light, which will contribute to the utilization of solar energy in the future.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2020
·
IF 3.99
Hanjun Wu,Weijun Zhang,Huali Zhang,Yi Pan,Xiaofang Yang,Zhiquan Pan,Xuejun Yu,Dongsheng Wang
In this work, the novel graphitic carbon nitride (g-C 3 N 4 ) and porous polyimide (PI) supported calcined hydrotalcite-like compounds (g-C 3 N 4 @PI@CHTLcs) were synthesized by co-precipitation and hydrothermal synthesis method, and systematically characterized by physical and chemical methods . The composites showed layered structure and a high thermal stability, and performed well in adsorption of tetracycline (TL), 2, 4-dichlorophenol (DP) and glyphosate (GH). The action pH value was ranged from 7 to 9 for TL and GH, and 3–9 for DP, respectively. The adsorption of TL and DP by g-C 3 N 4 @PI@CHTLcs conforms to the pseudo-first-order kinetic model . While for GH, the kinetic data fit well with pseudo-second-order model, indicating chemical adsorption via electrostatic interaction mechanism. Freundlich isothermal could better describe the adsorption process of TL, DP and GH. The maximum adsorption amounts of TL, DP and GH based on Langmuir isotherm model at 298 K were 231.1, 185.05 and 177.34 mg g −1 , respectively. The adsorption processes of TL, DP and GH were all endothermic and spontaneous, and showed excellent repeatability and stability in regeneration experiments. Additionally, the presence of chloride ion and humic acid (HA) showed no obvious effects on the adsorption process of organic contaminants. The diffusion mechanism of TL, DP and GH on the adsorption process was liquid membrane control. The adsorption mechanism might be the ion exchange between the layers of hydrotalcite, and the surface complexation and hydrogen bonding between various groups of PI and organic contaminants. The research showed that g-C 3 N 4 @PI@CHTLcs was effective in treatment of water containing various organic pollutants .
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高影响因子
Biochar
·
2022
·Vol. 4
·期 1
·1-19
·
IF 11.452
Han Yu,Gan Lu,Gong Han,Han Jiangang,Qiao Weichuan,Xu Lijie
Metal-free photocatalysts have attracted growing concern recently. Herein, the composites combining g-C 3 N 4 with wood pulp cellulose biochar (WPBC/g-C 3 N 4 ) were synthesized to effectively activate peroxymonosulfate (PMS) under visible light for the degradation of diclofenac (DCF). The incorporation of WPBC endowed g-C 3 N 4 with enhanced visible light absorption, improved charge separation capability, reduced electrical conductivity, and increased photocatalytic and PMS activation capability. Based on quenching tests, electron paramagnetic resonance (EPR), electrochemical analysis and solvent exchange experiments, both radical and nonradical mechanisms were proposed. Radical species including ·OH, h + , ·O 2 – were identified to contribute to DCF degradation. The 1 O 2 and electron transfer were the dominant nonradical pathways for DCF degradation. Moreover, the common influencing factors were examined, and DCF concentration was the most influential factor based on principal component analysis. Generally, the composites exhibited good reusability during consecutive runs. Based on HPLC/MS analysis, four intermediates were detected and the possible DCF degradation pathway was proposed. This work provided a potential strategy based on metal-free WPBC/g-C 3 N 4 for the photocatalytic activation of PMS to effectively degrade emerging contaminants in wastewater. Graphical abstract
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NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 47
·22830-22840
·
IF 3.925
Jiajun Nong,Yuexiang Jin,Jun Tan,Hongxia Ma,Yuan Lian
Realizing highly efficient utilization of solar energy for solving problems of environmental pollution and energy shortage has attracted increasing attention. Herein, Z-scheme two-dimensional (2D)/2D NiCo-LDH/g-C3N4 (LDH/CN) heterojunction composites were synthesized, which showed enhanced photocatalytic performance for tetracycline hydrochloride (TC) degradation and hydrogen (H2) generation under visible light irradiation. A 2D/2D heterojunction structure was formed between NiCo-LDH nanosheets (LDH) and g-C3N4 (CN), which was beneficial for the effective separation of photogenerated charge carriers. The active species of hydroxyl (˙OH), superoxide (˙O2−) and hole (h+) radicals contributed to TC photodegradation. The optimum photocatalyst showed a remarkably enhanced photocatalytic capability with a hydrogen generation rate of 451.7 μmol g−1 h−1. The improved photocatalytic activities may be attributed to the synergistic effects of the increased absorption of visible light, the separation efficiency of carriers and the 2D/2D heterostructure. A Z-scheme photocatalytic mechanism was proposed for the LDH/CN composite, showing dual advantages of a high redox ability and efficient charge carrier separation.
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Nanomaterials
·
2019
·Vol. 10
·期 1
·1
·
IF 4.034
Rui Geng,Juanjuan Yin,Jingxin Zhou,Tifeng Jiao,Yao Feng,Lexin Zhang,Yan Chen,Zhenhua Bai,Qiuming Peng
The construction of heterojunctions provides a promising strategy to improve photocatalytic hydrogen evolution. However, how to fabricate a nanoscale TiO2/g-C3N4heterostructure and hinder the aggregation of bulk g-C3N4using simple methods remains a challenge. In this work, we use a simple in situ construction method to design a heterojunction model based on molecular self-assembly, which uses a small molecule matrix for self-integration, including coordination donors (AgNO3), inorganic titanium source (Ti(SO4)2) and g-C3N4precursor (melamine). The self-assembled porous g-C3N4nanotube can hamper carrier aggregation and it provides numerous catalytic active sites, mainly via the coordination of Ag+ions. Meanwhile, the TiO2NPs are easily mineralized on the nanotube template in dispersive distribution to form a heterostructure via an N–Ti bond of protonation, which contributes to shortening the interfacial carrier transport, resulting in enhanced electron-hole pairs separation. Originating from all of the above synergistic effects, the obtained Ag/TiO2/g-C3N4heterogenous photocatalysts exhibit an enhanced H2evolution rate with excellent sustainability 20.6-fold-over pure g-C3N4. Our report provides a feasible and simple strategy to fabricate a nanoscale heterojunction incorporating g-C3N4, and has great potential in environmental protection and water splitting.Keywords:heterojunction;Ag/TiO2/g-C3N4;Co-assembly;hydrogen evolution
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PubMed
高影响因子
Environmental Science-Nano
·
2019
·Vol. 6
·期 9
·2850-2862
·
IF 7.704
Xiaoyu Bai,Yi Li,Liangbo Xie,Xiaohui Liu,Sihui Zhan,Wenping Hu
Antibiotics accumulate because of their extensive use and difficult degradation, which can lead to the formation of novel antibiotic resistant genes and bacteria, which can cause damage to human health and the ecological environment. Here, we designed a novel photo-electro-Fenton-like (PEF-like) system with bifunctional Z-scheme WO3/g-C3N4 for accelerated decomposition and enhanced mineralization of stubborn ciprofloxacin (CIP). This PEF-like system, accompanied by visible light activation, with the optimal WO3/g-C3N4 (1 : 6) composite exhibited outstanding removal efficiency of CIP compared with a single photocatalysis system and electro-Fenton-like (EF-like) system, and the elimination rate reached 100% within 2 h under visible light irradiation. The WO3/g-C3N4 (1 : 6) composite displayed the strongest visible light absorption, the weakest recombination of electron–hole pairs, the highest photocurrent response and the lowest electrochemical impedance compared with pristine WO3 and g-C3N4. Significantly, WO3/g-C3N4 (1 : 6) played a dual role in the PEF-like system which could not only produce ˙OH, ˙O2− and h+ during photocatalysis, but could also generate ˙OH through the reactions of W5+ and photoexcited electrons of g-C3N4 for the decomposition of H2O2. It was worth noting that this bifunctional PEF-like catalyst with photoelectric synergy could replace Fe2+ in a conventional electro-Fenton reaction and the pH range was broadened while still maintaining efficient degradation efficiency in the range of 2–9. The PEF-like system maintained a high elimination rate of CIP after five consecutive runs which revealed that it possessed prominent stability and feasibility.
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高影响因子
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Lianying Lu,Guohong Wang,Min Zou,Juan Wang,Jun Li
Hierarchical TiO 2 /g-C 3 N 4 heterojunction photocatalysts with well-defined multiscale porous TiO 2 framework are synthesized by simply calcinating tetrabutyl titanate and melamine precursors. The samples have been characterized by XRD, XPS, SEM, TEM, FTIR, nitrogen absorption-desorption equipment and TGA. The photocatalytic activity of these samples has been investigated in photo-degradation of Rhodamine B (RhB). The results show that calcining temperature critically affects the microstructure, surface area, interface structure and catalytic properties of the prepared samples. At the optimal calcining temperature of 550 °C, the apparent reaction rate constant of the catalyst is 55.0 × 10 −3 min −1 , which is 16.2 fold of pure TiO 2 (3.4 × 10 −3 min −1 ) and 3.4 fold of pure g-C 3 N 4 (16.4 × 10 −3 min −1 ), respectively. The strengthened visible-light-driven photocatalytic activity is attributed to the formation of a unique Z-scheme TiO 2 /g-C 3 N 4 heterojunction due to C- or N-doping at the surface of the porous TiO 2 framework. This mechanism explains the observation in a series of radical trapping experiments that superoxide ions and photo-generated holes play major roles in the photo-decolorizing process while hydroxyl radicals are also involved with a minor role.
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高影响因子
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
·
2020
·
IF 3.085
Junnan Qu,Yi Du,Yibing Feng,Jianyong Wang,Bo He,Minxing Du,Yang Liu,Nan Jiang
A visible-light-responsive hybrid photocatalyst , K-doped g-C 3 N 4 /BiOBr, has been synthesized by K-doped g-C 3 N 4 (K–CN) and BiOBr. The property of photocatalysts was characterized by XRD , FT-IR, TEM, SEM , DRS , PL , EIS and HPLC. The photocatalytic activity of K-doped g-C 3 N 4 /BiOBr was evaluated by degradation of Rhodamine B (RhB) and tetracycline hydrochloride under visible-light irradiation. The K-doped g-C 3 N 4 /BiOBr hybrid photocatalyst which contains K–CN with mass fraction of 20% (20K–CN/BiOBr) shows the best degradation efficiency of RhB. The degradation efficiency of RhB (20 mg/L) can be achieved to 99% and the degradation efficiency of tetracycline hydrochloride by BiOBr decreased with the increase of K-doped g-C 3 N 4 doping. The results of photocurrent and EIS assumed that the tight coupling between K–CN and BiOBr can enhance the separating efficiency of photo-generated carrier. In addition, the capture experiment proof that h + is the primary active substance in the system of reaction and ·OH is the auxiliary active substance. After five degradation experiments, the efficiency of the degradation of Rhodamine B by the sample can still reach 90%, which proves that the samples are stable. A new and efficient method is provided in this work to solve the pollution of organic dyes and antibiotics.
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 17
·6753-6764
·
IF 3.069
Qiannan Li,Yuguo Xia,Kangliang Wei,Xiaotong Ding,Shun Dong,Xiuling Jiao,Dairong Chen
Utilizing surface polarization to improve the separation efficiency of photoinduced carriers is considered to be an effective strategy to enhance the photocatalytic activity. Herein, a novel nonprecious metal-based P-doped g-C3N4 (PCN)/polyaniline (PANI)/BaTiO3 (BTO) (PPB) ternary photocatalyst with a hollow architecture was rationally designed and prepared by a combined wet-chemical and thermal treatment strategy. Except for the Z-scheme involved in PCN and PANI, the vertical polarization provided by ferroelectric BTO further improved the separation efficiency of the photoinduced charge carrier, resulting in an enhanced visible-light photocatalytic hydrogen production activity of 602 μmol h−1 g−1, which was 21-fold higher than that of pristine g-C3N4, and an apparent quantum efficiency of 4.16% at 420 nm. In addition, benefitting from this ternary heterojunction, the photoinduced electrons were concentrated on the intermediate p-type PANI while holes were left on the lateral n-type PCN involved in the Z-scheme, resulting in the retention of high oxidation–reduction potentials. Moreover, this approach to enhance the photocatalytic activity by constructing a Z-scheme heterojunction and surface polarization could expand to other photosystems, which provides a new avenue for the rational design and the synthesis of novel photocatalysts.
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高影响因子
ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Yong-Ting Li,Xiao-Li Zhang,Zhi-Kun Peng,Pu Liu,Xiu-Cheng Zheng
It is a crucial and urgent task to develop high performance catalysts for the hydrolysis of ammonia borane (NH3BH3, AB), which is presently thought to be an effective strategy for hydrogen generation. In this work, we immobilize the ultrafine RuNi alloy nanoparticles in the network of hierarchical porous g-C3N4 thin sheets with a facile adsorption–in situ reduction method. The structural and physicochemical properties of the as-prepared catalysts are studied using various techniques. The influence of different molar ratios of Ru to Ni in the catalysts on the hydrolytic dehydrogenation rate of AB is investigated to optimize the best one. The detailed reaction kinetics and the enhancing effect of NaOH with different dosages on the hydrolysis rate are studied through a series of experiments. Catalyzed by the optimal catalysts (denoted as Ru0.5Ni0.5/p-g-C3N4), the hydrolysis reaction is first-order and near zero-order relative to the Ru and AB concentrations, respectively. The corresponding turnover frequency reaches 840.3 min–1, and the apparent activation energy is as low as 14.1 kJ mol–1, which are greatly superior to many similar or counterpart catalysts previously reported. The results indicate the potential of the bimetallic alloy catalysts for the hydrolytic dehydrogenation of hydrogen storage materials.
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