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1.
ACS Appl Mater Interfaces ; 15(41): 48304-48315, 2023 Oct 18.
Article in English | MEDLINE | ID: mdl-37792963

ABSTRACT

Overcoming the negative impact of residual ionic liquids (ILs) on perovskite films based on an in-depth understanding of chemical interactions between ionic liquids and preparing perovskite precursor solutions is a great challenge when aiming to simultaneously achieve long-term stability and high efficiency within IL-based perovskite solar cells (PSCs). Herein, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), a type of IL, was introduced into the perovskite precursor solution, and carbon quantum dots (CQDs) were further introduced into the antisolvent to enhance the photovoltaic properties of PSCs. Both ILs and CQDs synergistically manipulate the crystallization process and passivate defects to obtain high-quality perovskite films. Besides serving as passivation sites to strengthen the collaboration between additives and perovskite materials, the cointroduction of CQDs further promotes the carrier transport process since it not only provides carrier channels at grain boundaries but also forms better energy alignment, which effectively overcomes the charge transfer loss caused by the steric hindrance of ILs. Based on such a synergistic effect of ILs and CQDs, the n-i-p MAPbI3-based PSCs achieve the highest efficiency of 20.84% with improved stability. This simple and low-cost synergistic integration method will subsequently provide direction for optimizing ILs to improve the photovoltaic performance of PSCs.

2.
J Colloid Interface Sci ; 652(Pt B): 2108-2115, 2023 Dec 15.
Article in English | MEDLINE | ID: mdl-37699329

ABSTRACT

The smooth and dense light-absorbing layer is an essential factor in polycrystalline solar cells to achieve high photovoltaic performance, while it remains challenging in perovskite solar cells because of the difficulty balancing the speed of crystal nucleation and growth in a solution way. Here, we explored a perovskite nucleation/growth compatible model via manipulating the intermediate complex induced by n-hexylamine (NHA) molecule, guiding us to adjustments perovskite nucleation and growth process. We found that the NHA can act as a gearbox-like molecule to sequentially reduce the perovskite nucleation barrier, promote the nucleation velocity, and retard the perovskite growth simultaneously to obtain uniform perovskite films; correspondingly, this modulation also yields the buried interface with fewer voids and low defects density. In addition, the hydrophobic NHA with long alkyl chain improves the moisture tolerance of the perovskite. The treated solar cell power conversion efficiency was 21.91 %. Importantly, in âˆ¼ 70 % humidity at 25 °C for 30 days, the efficiency of the device declined less than 5 %, exhibiting a good stability performance.

3.
Environ Sci Pollut Res Int ; 30(44): 99412-99426, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37612561

ABSTRACT

The construction of novel efficient catalysts for the treatment of organic pollutants in the aqueous environment is essential. The lamellar-like Cu-Al layered double hydroxides (CuAl-LDHs) with various mole ratios were synthesized by a simple route of co-precipitation, and the corresponding degradation characteristic was tested for the removal of tetracycline (TC) using PMS activation. The degradation efficiency of TC over CuAl-LDHs increased up to 93% within 10 min for the Cu/Al mole ratio of 3:1 and almost not changed at a higher mole ratio. For further calcining the optimal catalyst at 300 ℃, the degradation efficiency of TC was found to be increased to 96%. Sulfuric radicals and singlet oxygen were analyzed to be the main reason for the change in degradation characteristics, which was proved by radical quenching experiments and electron paramagnetic resonance technique. The parameters including PMS concentration, catalyst dosage, and reaction temperature on the TC degradation as well as the degradation mechanism for PMS activation were elaborated. The best proportion of CuAl-LDHs owned splendid stability and catalytic activity after reusing, which showed enormous potential in practical application.


Subject(s)
Hydroxides , Tetracycline , Anti-Bacterial Agents , Water , Catalysis , Peroxides
4.
Molecules ; 28(14)2023 Jul 20.
Article in English | MEDLINE | ID: mdl-37513413

ABSTRACT

The attainment of a well-crystallized photo-absorbing layer with minimal defects is crucial for achieving high photovoltaic performance in polycrystalline solar cells. However, in the case of perovskite solar cells (PSCs), precise control over crystallization and elemental distribution through solution processing remains a challenge. In this study, we propose the use of a multifunctional molecule, α-amino-γ-butyrolactone (ABL), as a modulator to simultaneously enhance crystallization and passivate defects, thereby improving film quality and deactivating nonradiative recombination centers in the perovskite absorber. The Lewis base groups present in ABL facilitate nucleation, leading to enhanced crystallinity, while also retarding crystallization. Additionally, ABL effectively passivates Pb2+ dangling bonds, which are major deep-level defects in perovskite films. This passivation process reduces recombination losses, promotes carrier transfer and extraction, and further improves efficiency. Consequently, the PSCs incorporating the ABL additive exhibit an increase in conversion efficiency from 18.30% to 20.36%, along with improved long-term environmental stability. We believe that this research will contribute to the design of additive molecular structures and the engineering of components in perovskite precursor colloids.

5.
J Colloid Interface Sci ; 646: 872-882, 2023 Sep 15.
Article in English | MEDLINE | ID: mdl-37235933

ABSTRACT

Rapid and sensitive detection of free bilirubin (BR) is essential for early diagnosis of jaundice and other hepatobiliary diseases. Inspired by sandwich immunoassay strategy, a multi-dimensional plasmonic coupling SERS platform composed of graphene oxide-Au nanostars nanocomposites (GANS NCs) and Au@Ag nanoparticles (NPs) was designed for label-free detection of BR. Specifically, GANS NCs were first prepared, and their excellent SERS activity was ascribed to synergistic enhancement effect of electromagnetic enhancement and chemical enhancement. Furthermore, SERS spectroscopy was used to monitor the adsorption process of BR. Subsequently, secondary reinforcing Au@Ag NPs were directly added, ultimately resulting in a multi-dimensional plasmonic coupling effect. The SERS enhancing mechanism of coupled system was discussed through electromagnetic field simulations. Interestingly, the high-density hotspots generated by strong plasmonic coupling in GANS-Au@Ag substrate could lead to more extraordinary SERS enhancing behavior compared to GANS NCs. Sensing efficiency of the SERS platform was examined by BR with a detection limit down to 10-11 M. Besides, GANS-Au@Ag NCs performed high uniformity and reproducibility. This work not only opens up a new avenue for construction of multi-dimensional plasmonic coupling system, but also offers a new biosensing technology for label-free diagnosis of BR-related diseases, thereby expecting to be applied in clinical diagnosis.


Subject(s)
Metal Nanoparticles , Metal Nanoparticles/chemistry , Spectrum Analysis, Raman/methods , Bilirubin , Reproducibility of Results , Silver/chemistry , Gold/chemistry
6.
Nanomaterials (Basel) ; 13(4)2023 02 04.
Article in English | MEDLINE | ID: mdl-36838992

ABSTRACT

A novel engineered carbon cloth (CC)-based self-cleaning membrane containing a Cu:TiO2 and Ag coating has been created via hydrothermal and light deposition methods. The engineered membrane with chrysanthemum morphology has superhydrophilic and underwater superoleophilic performance. The cooperativity strategy of Cu doping and Ag coating to the TiO2 is found to be critical for engineering the separation efficiency and self-cleaning skill of the CC-based membrane under visible light due to the modulated bandgap structure and surface plasmon resonance. The CC-based membrane has excellent oil-water separation performance when Cu is fixed at 2.5 wt% and the Ag coating reaches a certain amount of 0.003 mol/L AgNO3. The contact angle of underwater oil and the separation efficiency are 156° and 99.76%, respectively. Furthermore, the membrane has such an outstanding self-cleaning ability that the above performance can be nearly completely restored after 30 min of visible light irradiation, and the separation efficiency can still reach 99.65% after 100 cycles. Notably, the membrane with exceptional wear resistance and durability can work in various oil-water mixtures and harsh environments, indicating its potential as a new platform of the industrial-level available membrane in dealing with oily wastewater.

7.
Dalton Trans ; 52(8): 2317-2325, 2023 Feb 21.
Article in English | MEDLINE | ID: mdl-36723110

ABSTRACT

Surface-enhanced Raman scattering (SERS) is an analytical technique for the rapid detection of low-concentration analytes. However, the lack of uniform, stable, and recyclable substrate limits its wide applications. Here, Ag-doped MoS2 (AMSx) was prepared by the hydrothermal method. Band structures, LSV, and EIS characteristics confirmed that Ag doping can reduce the indirect band gap and increase the charge transfer between substrates and molecules. As a SERS substrate, AMSx displays excellent reproducibility, stability, and recyclability, which is beneficial for the application of the SERS substrate. Meanwhile, AMSx has excellent sensitivity with an enhancement factor of 4.07 × 106, comparable to that of precious metals. In addition, AMSx exhibits ultrahigh sensitivity in sensing bilirubin and Bisphenol A (BPA); the corresponding detection limit of both is 10-9 M, also better than that of previously reported semiconductors. This work provided a novel idea to synthesize low-cost ultrasensitive SERS substrates and the strategy of improving metal-chalcogenide semiconductor sensing.

8.
J Colloid Interface Sci ; 634: 651-663, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36549213

ABSTRACT

In this work, a novel surface-enhanced Raman scattering (SERS) sandwich strategy biosensing platform has been established for simultaneously detecting Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Fe3O4@SiO2-Au nanocomposites (NCs) with varying amounts of Au nanocrystals were prepared, and the effect of interparticle gaps on SERS activity was studied by finite-difference time-domain (FDTD) method. The optimal magnetic SERS-active substrates (FS-A5) were functionalized with the specific aptamers to act as capture probes. Meanwhile, graphene oxide-Au nanostars (GO-Au NSs) decorated with Raman reporters and aptamers were used as SERS tags. The loading density of Au NSs on GO was tuned to change the number of SERS active sites. In this proposal, E. coli and S. aureus were first captured by capture probes and then bound with SERS tags to form a sandwich-like structure, which caused enhanced electromagnetic field because of the dual enhancement strategy. Under optimal conditions, SERS platform could detect E. coli and S. aureus simultaneously, and the detection limit was as low as 10 cfu/mL. Our sandwich assay-based dual-enhanced SERS platform provides a new idea for simultaneously detecting multiple pathogens with high selectivity and sensitivity, and thus will have more hopeful prospects in the field of food safety.


Subject(s)
Metal Nanoparticles , Metal Nanoparticles/chemistry , Staphylococcus aureus , Escherichia coli , Limit of Detection , Silicon Dioxide , Oligonucleotides , Magnetic Phenomena , Spectrum Analysis, Raman/methods , Gold/chemistry
9.
J Colloid Interface Sci ; 635: 1-11, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36577350

ABSTRACT

Surface-enhanced Raman scattering (SERS) has attracted extensive attention as an ultrasensitive detection method. However, the poor biocompatibility and expensive synthesis cost of noble metal SERS substrates have become non-negligible factors that limit the development of SERS technology. Metal chalcogenide semiconductors as an alternative to noble metal SERS substrates can avoid these disadvantages, but the enhancement effect is lower than that of noble metal substrates. Here, we report a method to co-modify MoS2 by Ni and O, which improves the carrier concentration and mobility of MoS2. The SERS effect of the modified MoS2 is comparable to that of noble metals. We found that the improved SERS performance of MoS2 can be attributed to the following two factors: strong interfacial dipole-dipole interaction and efficient charge transfer effect. During the doping process, the incorporation of Ni and O enhances the polarity and carrier concentration of MoS2, enhances the interfacial interaction of MoS2, and provides a basis for charge transfer. During the annealing process, the introduction of O atoms into the S defects reduces the internal defects of doped MoS2, improves the carrier mobility, and promotes the efficient charge transfer effect of MoS2. The final modified MoS2 as a SERS substrate realizes low-concentration detection of bilirubin, cytochrome C, and trichlorfon. This provides promising guidance for the practical inspection of metal chalcogenide semiconductor substrates.

10.
Materials (Basel) ; 15(22)2022 Nov 19.
Article in English | MEDLINE | ID: mdl-36431707

ABSTRACT

PbBr2 has recently attracted considerable attention as a precursor for lead halide perovskite-based devices because of its attractive properties. It is known that pressure can modify the chemical and physical properties of materials by altering the distance between atoms in the lattice. Here, a global structure-searching scheme was used to explore the high-pressure structures of PbBr2, whose structures and properties at high pressure are still far from clear. Three new phases of PbBr2 were predicted in the pressure range of 0-200 GPa, and the pressure-driven phase transition sequence of orthorhombic Pnma (0-52 GPa) → tetragonal I4/mmm (52-80 GPa) → orthorhombic Cmca (80-153.5 GPa) → orthorhombic Immm (153.5-200 GPa) is proposed. Electronic calculations indicate a semiconductor-to-metallic transition of PbBr2 in the Cmca phase at ~120 GPa. Our present results could be helpful in improving the understanding of fundamental physical properties and provide insights to modulate the structural and related photoelectric properties of PbBr2.

11.
J Am Chem Soc ; 144(25): 11120-11128, 2022 Jun 29.
Article in English | MEDLINE | ID: mdl-35709383

ABSTRACT

Materials containing planar hypercoordinate motifs greatly enriched the fundamental understanding of chemical bonding. Herein, by means of first-principles calculations combined with global minimum search, we discovered the two-dimensional (2D) SrB8 monolayer, which has the highest planar coordination number (12) reported so far in extended periodic materials. In the SrB8 monolayer, bridged B8 units are forming the boron monolayer consisting of B12 rings, and the Sr atoms are embedded at the center of these B12 rings, leading to the Sr@B12 motifs. The SrB8 monolayer has good thermodynamic, kinetic, and thermal stabilities, which is attributed to the geometry fit between the size of the Sr atom and cavity of the B12 rings, as well as the electron transfer from Sr atoms to electron-deficient boron network. Placing the SrB8 monolayer on the Ag(001) surface shows good commensurability of the lattices and small vertical structure undulations, suggesting the feasibility of its experimental realization by epitaxial growth. Potential applications of the SrB8 monolayer on metal ions storage (for Li, Na, and K) are explored.

12.
Small Methods ; 5(8): e2100374, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34927868

ABSTRACT

Sodium (Na) ion-based dual-ion batteries (Na-DIBs) have attracted great attention, owing to their benefits of low cost, high working voltage, and environmental friendliness. However, the limited capacity and low tap density of currently reported anode materials restrict the further improvement of Na-DIBs. Herein, a micro-nano structure with vertically aligned WSe2 nanoflakes anchored tightly on a micron-sized carbon sphere (WSe2 /CS) is successfully constructed via combining the molecular coupling and self-assembly strategy. Within this hierarchical structure, the WSe2 nanoflakes can shorten the diffusion path for Na+ ions and alleviate structural deformation during the charge/discharge process; meanwhile, the micron-sized carbon core provides conductive support and helps improve the total tap density of the anode electrode. As a result, this micron-sized WSe2 /CS displays a high specific capacity of ≈252.8 mAh g-1 and good cycling performance with ≈92% capacity retention after 1200 cycles. Moreover, by pairing this WSe2 /CS anode with environmental friendly graphite as cathode, a proof-of-concept Na-DIB shows 85.6% capacity retention after 1000 cycles, which is among the best performances of previously reported Na-DIBs.

13.
Materials (Basel) ; 14(24)2021 Dec 12.
Article in English | MEDLINE | ID: mdl-34947246

ABSTRACT

It has been realized that the stoichiometries of compounds may change under high pressure, which is crucial in the discovery of novel materials. This work uses systematic structure exploration and first-principles calculations to consider the stability of different stoichiometries of Na-O compounds with respect to pressure and, thus, construct a high-pressure stability field and convex hull diagram. Four previously unknown stoichiometries (NaO5, NaO4, Na4O, and Na3O) are predicted to be thermodynamically stable. Four new phases (P2/m and Cmc21 NaO2 and Immm and C2/m NaO3) of known stoichiometries are also found. The O-rich stoichiometries show the remarkable features of all the O atoms existing as quasimolecular O2 units and being metallic. Calculations of the O-O bond lengths and Bader charges are used to explore the electronic properties and chemical bonding of the O-rich compounds. The Na-rich compounds stabilized at extreme pressures (P > 200 GPa) are electrides with strong interstitial electron localization. The C2/c phase of Na3O is found to be a zero-dimensional electride with an insulating character. The Cmca phase of Na4O is a one-dimensional metallic electride. These findings of new compounds with unusual chemistry might stimulate future experimental and theoretical investigations.

14.
Molecules ; 26(21)2021 Oct 23.
Article in English | MEDLINE | ID: mdl-34770813

ABSTRACT

Two-dimensional (2D) semiconductors with desirable bandgaps and high carrier mobility have great potential in electronic and optoelectronic applications. In this work, we proposed α-TeB and ß-TeB monolayers using density functional theory (DFT) combined with the particle swarm-intelligent global structure search method. The high dynamical and thermal stabilities of two TeB structures indicate high feasibility for experimental synthesis. The electronic structure calculations show that the two structures are indirect bandgap semiconductors with bandgaps of 2.3 and 2.1 eV, respectively. The hole mobility of the ß-TeB sheet is up to 6.90 × 102 cm2 V-1 s-1. By reconstructing the two structures, we identified two new horizontal and lateral heterostructures, and the lateral heterostructure presents a direct band gap, indicating more probable applications could be further explored for TeB sheets.

15.
Microsyst Nanoeng ; 7: 23, 2021.
Article in English | MEDLINE | ID: mdl-34567737

ABSTRACT

Ternary noble metal-semiconductor nanocomposites (NCs) with core-shell-satellite nanostructures have received widespread attention due to their outstanding performance in detecting pollutants through surface-enhanced Raman scattering (SERS) and photodegradation of organic pollutants. In this work, ternary Au@Cu2O-Ag NCs were designed and prepared by a galvanic replacement method. The effect of different amounts of Ag nanocrystals adsorbed on the surfaces of Au@Cu2O on the SERS activity was investigated based on the SERS detection of 4-mercaptobenzoic acid (4-MBA) reporter molecules. Based on electromagnetic field simulations and photoluminescence (PL) results, a possible SERS enhancement mechanism was proposed and discussed. Moreover, Au@Cu2O-Ag NCs served as SERS substrates, and highly sensitive SERS detection of malachite green (MG) with a detection limit as low as 10-9 M was achieved. In addition, Au@Cu2O-Ag NCs were recycled due to their superior self-cleaning ability and could catalyze the degradation of MG driven by visible light. This work demonstrates a wide range of possibilities for the integration of recyclable SERS detection and photodegradation of organic dyes and promotes the development of green testing techniques.

16.
ACS Appl Mater Interfaces ; 13(33): 39689-39700, 2021 Aug 25.
Article in English | MEDLINE | ID: mdl-34357753

ABSTRACT

To compensate for the photoelectric losses of planar heterojunction perovskite solar cells (PSCs), the development of high-quality textured absorbers with excellent light-harvesting ability and carrier extraction/transfer efficiency is of great significance to achieve a high-efficiency stable photovoltaic output. In this paper, we propose an in situ growth passivation technique to construct high-performance textured absorbers by adding a 2-amino-4-chlorophenol (AC) modifier consisting of multiple groups during the growth of textured perovskite. Initially, according to the Ostwald ripening mechanism, the strongly polar dimethylformamide (DMF) was used as the etchant to systematically study its synergistic effect on the morphology evolution, crystallization kinetics, light-trapping capability, and photovoltaic loss of textured absorbers. An appropriate amount of DMF induces formamidinium cations (FA+) to replace methylammonium cations (MA+) in the perovskite lattice while etching the absorber to form a texture configuration, which effectively broadens the spectral absorption range, thus greatly improving the light-trapping capacity and short-circuit current density of planar PSCs. In contrast, excess DMF deteriorates the device performance due to the excessive corrosion of the perovskite. Moreover, the introduction of the AC modifier is of great significance for passivating deep-level defects and accelerating the charge extraction/transfer. Owing to the electron-donating nature of the Lewis base, the hydroxyl groups with a higher electron density in AC molecules can better coordinate with Pb2+ ion defects, which effectively improves the crystallinity of the textured perovskite, thus suppressing the nonradiative recombination and ultimately improving the photovoltaic outputs of modified devices, particularly the fill factor and the open-circuit voltage. Thus, the photovoltaic performance of the AC-modified planar PSC is significantly better than that of the conventional textured device, with a reverse efficiency of 21.18% and forward efficiency of 20.77%. Owing to the synergistic effect of (1) the superior optical properties of the textured perovskite induced by DMF and (2) excellent charge dynamics driven by AC, the functionalized devices without encapsulation also exhibited good photovoltaic output stability and reproducibility. This work provides novel insights into the growth mechanism of textured absorbers and paves the way for more efficient and stable planar PSCs.

17.
ACS Appl Mater Interfaces ; 13(14): 16326-16335, 2021 Apr 14.
Article in English | MEDLINE | ID: mdl-33787224

ABSTRACT

An electron transport layer (ETL) with excellent conductivity and suitable band alignment plays a key role in accelerating charge extraction and transfer for achieving highly efficient planar perovskite solar cells (PSCs). Herein, a novel diluted-cadmium sulfide quantum dot (CdS QD)-assisted SnO2 ETL has been developed with a low-temperature fabrication process. The slight addition of CdS QDs first enhances the crystallinity and flatness of SnO2 ETLs so that it provides a promising workstation to obtain high-quality perovskite absorption layers. It also amazingly increases the conductivity of the SnO2 ETL by an order of magnitude and regulates the energy level matching between the SnO2 ETL and perovskite. These outstanding properties greatly accelerate the charge extraction and transfer. Thus, the MAPbI3-based PSCs with such a diluted-CdSQD-assisted SnO2 ETL achieve a maximum power conversion efficiency of 20.78% and obtain a better stability of devices in air. These findings testify the importance and potential of semiconductor QD modification on ETLs, which may pave the way for developing such composite ETLs for further enhancing photovoltaic performance of planar PSCs.

18.
ACS Appl Mater Interfaces ; 13(9): 10822-10836, 2021 Mar 10.
Article in English | MEDLINE | ID: mdl-33629583

ABSTRACT

The preferred orientation of crystalline films in hybrid perovskite materials is known to influence the performance of perovskite solar cells (PSCs). Although the preferred growth along the (112) directions has been reported to promote charge transport within the Pb-based polycrystalline perovskite films, the preferred orientation growth of this facet is still difficult to be achieved due to the higher formation energy compared with the (110) plane. Herein, Sn-Pb binary perovskite films with a well-controlled orientation along the (224) plane were achieved by introducing a simple ultrasonic treatment (UST) into the additive engineering fabricated method. UST is used to process the perovskite precursor solutions of tartaric acid (TA) modified Sn-Pb binary polycrystalline perovskite films to regulate the interactions between PbI2/SnI2 and TA in the intermediate phases. Meanwhile, TA-modulated MA0.9Cs0.1Pb0.75Sn0.25I3-based perovskite films with a preferred orientation of (224) crystal plane were obtained by precisely controlling the UST time to 15 min. The highest power conversion efficiency (PCE) of 15.59% with less hysteresis and improved stability was achieved, while realizing 8.64 and 25.32% enhancements of PCE compared with that of TA-based and control counterparts with (110) preferred orientation, respectively. Our work provides a promising route to obtain preferred orientation growth of polycrystalline perovskite films. In particular, we have shown that this approach improves the performance of Sn-Pb binary PSCs, while such methodology is quite flexible and could also be applied to other low-/non-toxic PSCs.

19.
J Hazard Mater ; 412: 125209, 2021 06 15.
Article in English | MEDLINE | ID: mdl-33517057

ABSTRACT

Real-time and in-situ monitoring of chemical reactions has attracted great attention in many fields. In this work, we in-situ monitored the photodegradation reaction process of methylene blue (MB) by Surface enhanced Raman scattering (SERS) technique. An effective and versatile SERS platform assembled from MoS2 nanoflowers (NFs) and TiO2 nanoparticles (NPs) was prepared successfully. The optimized MoS2/TiO2 substrate (MTi20) exhibits not only an ultra-high SERS response but also the excellent catalytic degradation performance to the contaminant MB, which provided a new material for real-time and in-situ monitoring the photodegradation process. Experiments prove that the detection limit is as low as 10-13 M, and degradation rate is as high as 97.2% in 180 s, respectively. And the activity of the substrate kept in the air for 90 days is almost unchanged. Furthermore, as a practical SERS substrate, MTi20 can also detect trace amounts of other harmful substances including malachite green (MG), bisphenol A (BPA) and endosulfan. Thus, this study come up with a new orientation at the real-time and in-situ monitoring of photocatalytic reaction and may be applied in environmental monitoring and food security fields in the future.

20.
ACS Omega ; 5(45): 29292-29299, 2020 Nov 17.
Article in English | MEDLINE | ID: mdl-33225160

ABSTRACT

The polycrystalline thin films of BiFeO3 (BFO) and Bi0.90Ho0.10Fe1-xTixO (x = 0, 0.025, 0.05, 0.10, 0.15, and 0.20) were successfully synthesized by the simple sol-gel method. X-ray diffraction and Raman spectra revealed the substitution of Bi and Fe by Ho and Ti, respectively, and correspondingly a structural phase transition from the rhombohedral phase to orthorhombic phase. The field-emission scanning electron microscopy and transmission electron microscopy images indicated that the average size of the particles was decreased and the surface homogeneous agglomeration was enhanced with the increased concentration of Ti to x = 0.05. The X-ray photoelectron spectroscopy measurements illustrated that Fe3+ and O2- ions tended to increase with the Ti concentration increase, which accounted for the enhanced super-exchange interaction between Fe3+ and O2-. Because of the reduced concentration of oxygen vacancies, Ho and Ti ions with a smaller ionic radius and denser surface structure, the Ho and Ti co-substituted films with an appropriate concentration of Ti (x = 0.05) showed an optimal saturation magnetization (M s) of 44.23 emu/cm3 and remanent magnetization (M r) of 4.62 emu/cm3, which were approximately 1.8 times and 1.9 times than that of the pure BFO, respectively. This work opened up an effective way to modulate the structure and properties of BFO-based materials.

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