Catalysis Science & Technology
·
2021
·Vol. 11
·期 24
·7963-7972
·
IF 6.119
Anyu Liu,Jianqiang Hu,Jiale He,Xinyue Huang,Na Hu,Yuqin Li,Qingling Huang,Shien Guo,Xin Liu,Zhen Yang,Yong Zhou,Zhigang Zou
O-doped g-C3N4/In2S3 hierarchical heterostructures with a direct Z-scheme mechanism were devised and constructed simply via loading In2S3 nanoflakes on the surface of O-doped g-C3N4 (OCN) hierarchical structures, in situ, employing pre-obtained OCN (prepared by condensation of oxalic acid and urea) and indium(III) dimethyldithiocarbamate (In(dedc)3) as precursors. Analyses of the energy band structure, density functional theory (DFT) computations and DMPO-ESR spin-trapping experiments demonstrate that the formation of a perfect heterointerface with a staggered alignment of band edges between OCN and In2S3 (IS), owing to their close contact, enables photoexcited carriers to migrate via a Z-scheme route, which can maintain the higher reduction and oxidation capability of electrons and holes, respectively. Furthermore, the Z-scheme OCN/IS heterostructures efficaciously facilitate the separation of photogenerated electrons and holes, as demonstrated using PL spectra, transient photocurrent densities and electrochemical impedance spectra (EIS). These lead to the enhanced photocatalytic activity towards reducing Cr(VI) into Cr(III). Besides, the integration of OCN with IS can enhance the responsiveness to visible light based on the results of UV-vis DRS, thereby inducing the formation of more electrons and holes,and also contributing to the improvement of the photocatalytic activity for Cr(VI) reduction. In consequence, all the pre-prepared OCN/IS hybrids possess markedly improved photocatalytic activities for Cr(VI) reduction, relative to pure OCN and pristine IS under visible light (λ > 420 nm) illumination. With the increase in the In(dedc)3 to OCN mass ratio (R), the photocatalytic activities of these OCN/IS hybrids increase first and then decrease. The sample with an optimum R of 0.9 (OCN/IS-0.9) can remove nearly 100% of Cr(VI) after 40 min of illumination, being superior to most of g-C3N4-based and IS-based photocatalysts. Its reaction rate constant for Cr(VI) photoreduction (0.08947 min−1) is 56.7 fold and 8.8 fold higher than that of pure OCN (0.00155 min−1) and pristine IS (0.00913 min−1), respectively. This work affords a deep understanding on designing preeminent Z-scheme photocatalysts towards the degradation of Cr(VI) under visible-light irradiation.
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Kai Xuan,Taiguang Li,Yongmei Hao
Adequate separation of photogenerated carriers plays an important role in the photocatalytic degradation of pollutants. Here, a noble-free spatially separated photocatalyst rGO-CdS-MnO x (GCM) has been designed for removing environmental pollutants efficiently. rGO and MnO x are employed as the collectors of photoinduced electrons and holes, respectively. Under light irradiation, the electrons and holes motivated by CdS can directionally transfer to the rGO and MnO x , leading to the exposure of both reduction and oxidation surfaces, thereby enhancing the photocatalytic activity. Our results demonstrated that GCM-30 can remove 86.56 % of carbamazepine and 95.83 % of tetracycline hydrochloride within 30 min and 15 min, respectively, and 95.49 % of Cr (VI) within 21 min. Our work demonstrates that this dual functional photocatalyst may provide new strategies for the spatially separated photocatalysts for removing environmental pollutants.
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Journal of Materials Chemistry C
·
2023
·
IF 6.4
Tianqi Zhao,Renagul Abdurahman,Qianting Yang,Ruxiangul Aiwaili,Xue-Bo Yin
Herein, we designed and prepared the persistent luminescence nanoparticles (PLNPs) of γ-Ga2O3:Cr,Ba rationally with Cr ions to achieve the near-infrared (NIR) emission at 700 nm and Ba ions to improve the emission intensity by inducing trap distribution. Energy transfer between γ-Ga2O3 and Cr ions occurs as the emission at 508 nm decreases and that at 700 nm increases along with the increased content of Cr ions. In combination with the trap depth, band gap of the host, and energy levels of Cr ions, an emission mechanism was proposed. Thus, NIR emission (700 nm), high brightness, large Stokes shift (446 nm), and long afterglow time (90 min) were achieved with the optimal γ-Ga2O3:0.0025Cr,0.0012Ba (γGCB) under excitation at 254 nm. The emission intensity of γGCB is temperature-dependent for non-contact ratiometric temperature sensing, and temperature linearity ranging from 300 to 420 K was achieved with an absolute sensitivity of 3.4% K−1. γGCB and γ-G2O3 are white under sunlight but exhibit red and green emissions under single excitation at 254 nm. Thus, Morse and binary codes are adapted to achieve encryption information transfer with the combination of γGCB and γ-G2O3. This work provides ideas for selecting a host, emission center, and trap for PLNPs with desirable properties and thus achieves extensive applications, as validated with ratiometric temperature sensing and encryption information transfer.
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ELECTROCHIMICA ACTA
·
2023
·
IF 6.6
Guiying Tian,Jian Gao,Minrui Wang,Xintao Wen,Yutong Liu,Jun Xiang,Lei Zhang,Penggao Cheng,Jianping Zhang,Na Tang
Current explosive demand in raw lithium greatly boosts lithium mining, and electrochemical Li-extraction using spinel LiMn 2 O 4 (LMO) from original brine has gained much attentions. In this study, Cr-doped LMO is prepared via a facile precipitation-calcination to elucidate the structural alterations and suppress Jahn-Teller distortion, and a novel hybrid capacitive deionization (HCDI) system of “Li-poor LiMn 1.8 Cr 0.2 O 4 ||brine (recovery liquid)||activated carbon” is constructed for electrochemical Li-extraction. The results prove that Cr-doping effectively suppresses Mn 3+ disproportionation induced by Jahn–Teller distortion, leading to a stabilized spinel framework for long lifespan. Importantly, the Cr-doping LMO realizes a stable (de)lithiation over 500 cycles with low manganese dissolution rate of 0.027% per cycle. Meanwhile, the Li-extraction capacity can reach 22 mg g −1 in 1.0 M LiCl electrolyte with retention rate of 86.05% after 500 cycles. In the assembled HCDI system, average Li-extraction capacity in brine reaches ∼15 mg g −1 after 15 cycles. Therefore, the HCDI system using Cr-doping LMO could introduce a new perspective for the industrial Li-extraction facing original brine.
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CARBOHYDRATE POLYMERS
·
2023
·
IF 11.2
Zhouyu Miao,Mengya Mu,Hou-Yong Yu,Yanjuan Dong
This study presents a novel and environmentally friendly method for producing cellulose microspheres (CM) with controllable morphology and size using electrostatic droplets. The traditional droplet method for CM production requires complex equipment and harmful reagents. In contrast, the proposed method offers a simple electrostatic droplet approach to fabricate CM10 at 10 kV, which exhibited a smaller volume, linear microscopic morphology, and a larger specific surface area , with a 36.60 % improvement compared to CM0 (prepared at 0 kV). CM10 also demonstrated excellent underwater structural stability, recovering in just 0.5 s, and exhibited the highest adsorption capacity for Cr(VI) at 190.16 mg/g, a 72.15 % improvement over CM0. This enhanced adsorption capacity can be attributed to the unique structure of CM10 and the introduction of more amino groups. Moreover, CM10 displayed good cyclic adsorption capacity and high dynamic adsorption efficiency, making it highly suitable for practical applications. CM10 exhibited remarkable adsorption capacity, stability, and practical value in treating Cr(VI) wastewater. This work proposes a simple and eco-friendly method for producing CM with excellent structural controllability and stability, providing an effective route for wastewater treatment .
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Meilin Liu,Taotao Li,Cheng Zhang,Yu Zheng,Chenqing Wu,Jian Zhang,Kui Zhang,Zhongping Zhang
In this work, amino-functionalized mesoporous silica nanospheres (NH 2 -mSiO 2 ) anchored with carbon dots (CDs) have been designed to construct an outstanding fluorescent sensor for heavy metal detection. Uniform mSiO 2 was chosen to provide an optically transparent scaffold for immobilizing CDs. With the help of amino group modification on the surface of silica, benzene-1,4-diboronic acid (BA) was used as raw material to load CDs in the pores of mSiO 2 by one-step solvothermal method. The proposed nanohybrid can solve the problem of aggregation-induced fluorescence quenching, leading to bright blue emission at 450 nm. Meanwhile, the fluorescence of NH 2 -mSiO 2 @CDs showed high sensitivity to Cr(VI) in acetic acid buffer solution (pH = 4) with detection limit as low as 5 nM by inner filter effect (IFE) and electrostatic interaction (EI). The proposed method can also be extended to other CDs-based detection systems for chemical/biological sensors.
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LUMINESCENCE
·
2021
·Vol. 37
·期 1
·72-81
·
IF 2.464
Haonan Zhao,Junfeng Zhang,Xiaolian Lin,Huihui Li,Qinhe Pan
Cr(VI) is a type of dangerous effluent that has caused great harm to human health and the environment. Recognition and perception of Cr(VI) by artificial receptors has attracted extensive attention. A novel fluorescent chemical sensor based on the 5,7-dihydroxyflavone skeleton was designed and synthesized for the selective recognition of Cr(VI). As confirmed by fluorescence technology, the fluorescent probe 4-dimethylaminobenzyl chrysin ester–Zn (DBC–Zn) showed high sensitivity and selectivity for dichromate and a fast response (less than 30 sec) recognition. The fluorescence intensity of DBC–Zn varies linearly with the concentration of Cr(VI) in the range 0.1–1 μM. The detection limit of Cr 2 O 7 2− by DBC–Zn is 2.3 nM, which is far lower than the national safe drinking water standard stipulated by the US Environmental Protection Agency (1.9 μM). The quenching mechanism of the probe can be attributed to the interaction of the dynamic quenching effect and the fluorescence internal filtration effect. In addition, the probe has good stability in both neutral and alkaline environments, and the accuracy of quantitative analysis of Cr 2 O 7 2− in lake water or tap water is more than 80%. The test paper based on DBC–Zn can effectively detect Cr 2 O 7 2− at the concentration of 100 ppb. This shows that the probe has a certain practical application value.
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Catalysts
·
2021
·Vol. 11
·期 10
·1186
·
IF 4.146
Yarui Wang,Wanchao Yu,Fanglan Geng,Lixia Zhao,Yawei Wang
The coexistence of pollutants presents a great challenge to the implementation of photocatalysts. In this work, a novel MIL-101(Fe)/TiO2composite prepared by in situ growth of MIL-101(Fe) on TiO2was developed for the synergetic oxidation of MC-LR and Cr(VI) reduction. The heterojunction material shows elevated photocatalytic behavior under ultraviolet compared with the unary pollutant system. Furthermore, quenching experiments and electron spin resonance confirm that the enhanced photodegradation behavior is related to the synergistic effect between the photocatalytic reduction and oxidation process, in which MC-LR consumes the holes and Cr(VI) captures electrons, followed by efficient charge separation through the conventional double-transfer mechanism between MIL-101(Fe) and TiO2. This investigation provides a deeper understanding of the construction of MOFs/semiconductor heterojunctions for the pollutants removal in multi-component contaminants system.Keywords:TiO2@MOF photocatalyst;Cr(VI);microcystin-LR;synergetic removal
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Journal of Environmental Sciences
·
2021
·
IF 5.565
Ruolin Cao,Shiqing Liu,Xinyu Yang,Chunfeng Wang,Yanbin Wang,Wanfeng Wang,Yunqing Pi
Although widely used in permeation reaction barrier (PRB) for strengthening the removal of various heavy metals, zero-valent iron (ZVI) is limited by various inherent drawbacks, such as easy passivation and poor electron transfer . As a solution, a synergistic system with PRB and electrokinetics (PRB-EK) was established and applied for the efficient removal of Cr(VI)-contaminated groundwater. As the filling material of PRB, ZVI/Fe 3 O 4 /activated carbon (ZVI/Fe 3 O 4 /AC) composites were synthesized by ball milling and thermal treatment. A series of continuous flow column experiments and batch tests was conducted to evaluate the removal efficiency of Cr(VI). Results showed that the removal efficiency of Cr(VI) remained above 93% even when the bed volume (BV) reached 2000 under the operational parameters (iron/AC mass ratio, 2:1; current, 5 mA). The mechanism of Cr(VI) removal by the PRB-EK system was revealed through field emission scanning electron microscopy images, X-ray diffraction, X-ray photoelectron spectroscopy, Fe 2+ concentration, and redox potential (E h ) values. The key in Cr(VI) reduction was the Fe 2+ /Fe 3+ cycle driven by the surface microelectrolysis of the composites. The application of an externally supplied weak direct current maintained the redox process by enhancing the electron transfer capability of the system, thereby prolonging the column lifetime. Cr(VI) chemical speciation was determined through sequential extraction, verifying the stability and safety of the system. These findings provide a scientific basis for PRB design and the in-situ remediation of Cr(VI)-contaminated groundwater.
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CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Guanliang Yu,Weirong Wang,Chun Jiang
Adjusted crystal fields can lead to new hybrid materials with promising optical performance. Transition metal ions (TMIs) with d-d electron transitions are sensitive to their surroundings and can be ideal candidates for crystal field research. Herein, we have selected single Ni 2+ -doped spinel oxide nanocrystals as a model system to systematically explore luminescence mechanisms in different crystal fields. Ni 2+ -doped ZnAl 2 O 4 , ZnGa 2 O 4 , and ZnCr 2 O 4 nanospinels with broad near-infrared (NIR) emission bands fully cover the second biological window (1100–1400 nm). We have developed a ZnX 2 O 4 (X = Al, Ga or Cr) (ZXO) spinel framework system using a melting-evaporation procedure, and the whole fabrication period only required 20 min. By changing X ions in the ZXO matrix framework, linear tunable photoluminescence was successfully realized. A sample with a mixed phase of ZnAl 2 O 4 and ZnCr 2 O 4 (ZACO) was also prepared using the same method, and ultrabroadband emissions ranging from 1050-1550 nm were detected. It is valuable to further explore the combinations based on these frameworks to realize tunable emission spectra. Fundamental research on the physical processes will open a new gateway for further research of TMI-doped nanocrystals with promising luminescence properties and broaden the applications to a variety of areas, especially in the biomedical field.
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Jiaxing Wang,Yaseen Muhammad,Zhu Gao,Syed Jalil Shah,Shuangxi Nie,Lihan Kuang,Zhongxing Zhao,Zhiwei Qiao,Zhenxia Zhao
Adsorption of volatile organic compounds (VOCs) under high humidity is crucial for metal–organic frameworks (MOFs) in practical applications. To enhance competitive adsorption of VOCs under humidity, polyethylene glycol (PEG) with hydrophobic short-chains was implanted as hydrophobic barrier into MIL-101(Cr). Characterization and simulation results showed that the terminal –OH groups of PEG chains were coordinated with the Cr sites in MIL-101(Cr) and formed a hydrophobic pore (11.2 Å) of “cage-in-cage” geometry. PEG chains significantly hindered the diffusion of water into the MOFs while allowed toluene molecules. The new hydrophobic pores of PEG 5 @MIL-101 enhanced adsorption capacity and diffusivity for toluene by 30.8% (4.68 mmol/g at 1 mbar) and 31.5% (1.88 × 10 −2 ), while decreased adsorption capacity and diffusivity for water by 53.7% and 26.8% compared to primary MOF. Breakthrough curve showed 3.3 times of toluene working capacity on PEG 5 @MIL-101 at 80% RH compared to pristine MIL-101(Cr).
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Zhiyun Kong,Yajie Du,Junfu Wei,Huan Zhang,Longwei Fan
Removing hexavalent chromium (Cr(VI)) from aqueous solution is strategically important. A novel and selective adsorbent was synthesized using a high electron beam irradiation pre-grafting and post-surface ion imprinting method using Cr(VI) and polypropylene (PP) fibers as the template and substrates, respectively. The results obtained using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TG) indicated that the prepared sorbent was successfully synthesized. At the same time, the adsorption performances were studied through batch experiments. The results exhibited rapid adsorption kinetics, a wide working pH range, and excellent selectivity and regeneration. The equilibrium adsorption was achieved within 30 min, the maximum sorption capacity of Cr(VI)-IIPs was 156.5 mg g −1 and partition coefficients (PC) was 0.591 mg g −1 uM −1 at 400 mg L −1 initial concentration and 298 K. The relative selectivity coefficients of the ion-imprinted polymer (IIP) for Cr 2 O 7 2− /HPO 4 2− and Cr 2 O 7 2− /NO 3 − were 36.7 and 39.9, respectively. In addition, the prepared sorbent has a negligible loss in adsorption capacity after five cycles. IIP has good application prospects in the selective removal of Cr(VI) ions.
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