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1.
Chemosphere ; 287(Pt 3): 132283, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826942

RESUMO

The present investigation demonstrates an enhancement of the visible photocatalytic activities by C ion implantation in ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs were prepared by seed layer assisted solution-phase growth and implanted with 70 keV carbon ions at various fluencies: 1E15, 5E15, 1E16, and 3E16 ions/cm2. X-ray diffraction and FESEM results revealed the crystalline 1D ZnO NRAs having a length of ∼3 µm with a diameter in the range of 150-200 nm. C implantation induces the absorption towards the visible region and a substantial decrease in the optical bandgap energy from 3.2 eV to 2.43 eV. The photocatalytic activities (PC) of C ion-implanted ZnO NRAs were investigated through the degradation of 4-Nitrophenol (4-NP) and methylene blue dye (MB) under ambient visible light irradiation. The degradation efficiency of C ion-implanted ZnO NRAs increases compared to the pristine ZnO NRAs from 60.12% to 93.7% and 48.6 to 97.5% for MB and 4-NP, respectively. The synergistic effects of low energy carbon ion-induced bulk and surface interface electronic states facilitate a narrow band of visible light absorption and efficient charge separation to increase the visible-light-driven photocatalytic performance of ZnO NRAs.


Assuntos
Azul de Metileno , Óxido de Zinco , Carbono , Catálise , Íons , Luz , Nitrofenóis
2.
J Hazard Mater ; 421: 126775, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34358971

RESUMO

Hydroquinone (HQ) and catechol (CC) are the two major dihydroxybenzene isomers, are considered one of the toxic pollutants in wastewater, which often coexisted and impede each other during sample identification. For practical analysis and simultaneous detection of HQ and CC in wastewater, we fabricate a hybrid electrochemical sensor with electrospun one-dimensional (1D) MnMoO4 nanofibers coupled with a few-layered exfoliated two-dimensional (2D) MXene. The facilitated abundant defective edges of 1D MnMoO4 and 2D MXene nanoarchitecture accelerated the effect of synergistic signal amplification and exhibited high electrocatalytic activity towards the oxidation of hydroquinone and catechol. MnMoO4-MXene-GCE showed oxidation potentials of 0.102 V and 0.203 V for hydroquinone and catechol, respectively. It revealed the distinguished and simultaneous detection range of 0.101 V with a strong anodic peak current. Noteworthily, the proposed 1D-2D hybridized MnMoO4-MXene-GCE sensor exhibited a wide linear response from 5 nM to 65 nM for hydroquinone and catechol. Moreover, it showed a low detection limit of 0.26 nM and 0.30 nM for HQ and CC with high stability, respectively. The feasible 1D-2D MnMoO4-MXene nanocomposite-based biosensor effectively detected hydroquinone and catechol in hazardous water pollutants using the differential pulse voltammetric technique with recovery values.


Assuntos
Técnicas Biossensoriais , Nanocompostos , Nanofibras , Eletrodos , Águas Residuárias
3.
Mikrochim Acta ; 188(3): 106, 2021 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-33651208

RESUMO

Unique Ni2CoS4-carbon nanofiber (CNF) composite nanostructures were fabricated using a simple electrospinning-assisted hydrothermal route and used for the rapid and accurate electrochemical oxidation of glucose in real samples at the trace level. Electrochemical impedance spectroscopy and cyclic voltammetry of unmodified and modified electrodes revealed low charge-transfer resistance and the excellent electrocatalytic sensing of glucose when using the Ni2CoS4-CNF at a low potential due to the combined benefits of the highly conductive Ni2Co2S4 anchored to the large surface area of the CNFs. Amperometric analysis of the fabricated sensor has shown an extremely low limit of detection (0.25 nM) and a large linear range (5-70 nM) for glucose at a working potential of 0.54 V (vs. Hg/HgO). The practicability of the Ni2CoS4-CNF for use in glucose determination was tested withl human saliva, blood plasma, and fruit juice samples. The Ni2CoS4-CNF/GCE showed acceptable recovery values for human saliva (99.1-100.8%), blood plasma (98.6-101.5%), and fruit juice (95.1-105.7%) samples. The proposed sensor also exhibited outstanding electroanalytical characteristics for glucose oxidation in these samples, including reusability, repeatability, and interference resistance, even in the presence of other biological substances and organic and inorganic metal ions.

4.
Nanoscale ; 12(26): 14047-14060, 2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32582888

RESUMO

Nanorod (NR) arrays offer commendable visible-light-driven photocatalytic performances. Herein, we describe the construction of a ternary ZnO-ZnS-Gd2S3 nanostructural array in which a sulfidation process is used to decorate a Gd2S3 shell layer with a ZnS interface over vapor-phase-grown vertically-aligned ZnO. With control over the shell-wall thickness, the shell layer of ∼25 nm wall thickness on the ultra-long ZnO NR arrays exhibited a higher catalytic efficiency close to 3.3, 2.0, 1.2, and 1.8 times those of the bare ZnO, the ZnO-ZnS, the Gd2S3-decorated (∼10 nm) and Gd2S3 shell-layered (∼40 nm) ZnO-ZnS core-shell structures, respectively. The core-shell geometry and the shell-wall thickness with maximized contact interface afforded increased light absorption in the visible region and effectively retarded the recombination rate of the photoinduced charge carriers by confining electrons and holes separately, thus providing advantages in terms of the degradation of the pharmaceutical residue tetracycline and the industrial pollutant 4-nitrophenol in wastewater.


Assuntos
Nanotubos , Óxido de Zinco , Antibacterianos , Sulfetos , Compostos de Zinco
5.
Nanotechnology ; 31(27): 275402, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32182601

RESUMO

Electrochemical water splitting represents an ideal strategy for producing clean hydrogen as an energy carrier that serves as an alternative to fossil fuels. As an effective method for hydrogen production, an efficient inexpensive multifunctional electrocatalyst with high durability is designed. Herein, we describe the heterostructural design of a three-dimensional catalytic network with self-embedded CoNi2S4 nanograins grown on electrospun carbon nanofibers (CoNi2S4-CNFs) with anchored thin-layer reduced graphene oxide. This is achieved via facile electrospinning followed by carbonization, low-temperature sulfidation, and surface functionalization. As a bifunctional catalyst, CoNi2S4-CNFs exhibited robust high activity toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. The anchored ultrathin graphene oxide layer promoted the stability and durability of the catalytic network with an efficient path for the transportation of electrons. The rGO-anchored CoNi2S4-CNFs yielded overpotential values of 228 mV and 205 mV for the HER and OER, respectively, that drives a current density of 20 mA cm-2 in an alkaline medium. Notably, the excellent electrochemical properties are attributed to the functional effect of the CoNi2S4 on the CNF network. The ultrathin feature of rGO improved the durability of the catalytic network. Moreover, using the rGO-anchored CoNi2S4-CNFs as a cathode and anode in a two-electrode water splitting system required a cell voltage of only 1.55 V to reach a current density of 10 mA cm-2. These CNFs exhibited outstanding durability for 48 h. The present work offers new insight for the design of a catalytic network with a non-noble metal catalyst that exhibits excellent electrocatalytic activity and durability on the metal sulfides in overall water splitting.

6.
J Hazard Mater ; 391: 122249, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32097876

RESUMO

Heterogeneous photocatalysis has been proven to be a promising approach to overcome the great challenges encountered with conventional technologies for environmental remediation. Herein, for the first time, a novel hierarchical architecture of nitrogen-doped TiO2@Bi2WxMo1-xO6 (N-T@BWMO-x, x = 0-1.0) was rationally designed and fabricated through an electrospinning route followed by a solvothermal process. The photocatalytic activity of the as-prepared samples was evaluated based on the degradation of tetracycline hydrochloride (TC) under visible-light irradiation. The results indicated that the molar fraction of W/Mo has a strong impact on the photocatalytic efficiency and photoelectrochemical performance of the N-T@BWMO composites. Compared to N-TiO2 and the binary composites, N-T@BWMO-0.25 exhibited outstanding photocatalytic activity and significant cycling stability. The enhanced photocatalytic activity can be synergistically linked to the excellent native adsorption, extended light-harvesting region, hierarchical structure, and strong interfacial interaction between N-TiO2 and BWMO, which can effectively prolong the lifetime of charge-carriers. Moreover, active species-trapping and electron paramagnetic resonance results confirmed that holes and superoxide radicals were the dominant active species responsible for TC removal. A possible photocatalytic mechanism underlying the degradation of TC by N-T@BWMO-0.25 is also proposed. We expect that our findings will provide new insights into the use of highly efficient core-shell heterostructure photocatalysts, with potential applications in environmental decontamination.

7.
Nanomaterials (Basel) ; 10(2)2020 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-32050408

RESUMO

A flexible asymmetric supercapacitor (ASC) with high electrochemical performance was constructed using reduced graphene oxide (rGO)-wrapped redox-active metal oxide-based negative and positive electrodes. Thin layered rGO functionality on the positive and the negative electrode surfaces has promoted the feasible surface-active sites and enhances the electrochemical response with a wide operating voltage window. Herein we report the controlled growth of rGO-wrapped tubular FeMoO4 nanofibers (NFs) via electrospinning followed by surface functionalization as a negative electrode. The tubular structure offers the ultrathin-layer decoration of rGO inside and outside of the tubular walls with uniform wrapping. The rGO-wrapped tubular FeMoO4 NF electrode exhibited a high specific capacitance of 135.2 F g-1 in Na2SO4 neutral electrolyte with an excellent rate capability and cycling stability (96.45% in 5000 cycles) at high current density. Meanwhile, the hydrothermally synthesized binder-free rGO/MnO2 nanorods on carbon cloth (rGO-MnO2@CC) were selected as cathode materials due to their high capacitance and high conductivity. Moreover, the ASC device was fabricated using rGO-wrapped FeMoO4 on carbon cloth (rGO-FeMoO4@CC) as the negative electrode and rGO-MnO2@CC as the positive electrode (rGO-FeMoO4@CC/rGO-MnO2@CC). The rationally designed ASC device delivered an excellent energy density of 38.8 W h kg-1 with a wide operating voltage window of 0.0-1.8 V. The hybrid ASC showed excellent cycling stability of 93.37% capacitance retention for 5000 cycles. Thus, the developed rGO-wrapped FeMoO4 nanotubes and MnO2 nanorods are promising hybrid electrode materials for the development of wide-potential ASCs with high energy and power density.

8.
J Colloid Interface Sci ; 562: 29-41, 2020 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-31830629

RESUMO

Selectivity of catalysts toward harmful cationic pollutants in industrial wastewater remains challenging but is of crucial importance in environmental remediation processes. Here, we present a complex network of a hydrolyzed polymer of intrinsic microporosity (HPIM)-based electrospun nanofibrous web with surface functional decoration of ZnO nanorods (NRs) as a hierarchical platform for selective and rapid degradation of cationic dyes. Over a single species or binary mixtures, cationic dyes were selectively adsorbed by the HPIM surface, which then rapidly degraded under simultaneous photoirradiation through the ZnO NRs. Both HPIM and ZnO exhibited high electronegative surfaces, which induced the selectivity towards the cationic dyes and rapidly degraded the pollutants with the production of reactive oxygen species under photoirradiation. Further, as a free-standing web, the catalytic network could be easily separated and reused without any significant loss of catalytic activity after multiple cycles of use. The hierarchical platform of ZnO/HPIM-based heterostructures could be a promising catalytic template for selective degradation of synthetic dyes in mixed wastewater samples.

9.
ACS Omega ; 4(7): 11973-11979, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31460308

RESUMO

The present study focuses on the effects of nitrogen (N) ion implantation in vertically aligned ZnO nanorod arrays (NRAs) and the photocatalytic degradation of acetaminophen. The X-ray diffraction of these NRAs exhibit a wurtzite structure with a predominant (002) diffraction peak that shifts slightly after N-ion implantation. The field emission scanning electron microscopic images of as-prepared NRAs show a length of ∼4 µm and diameter of ∼150 nm. UV-visible spectroscopy reveals that the band gap of pristine ZnO NRAs decreases from 3.2 to 2.18 eV after N-ion implantation. Under visible irradiation, the N-ion-implanted ZnO catalyst exhibits significant enhancement of the photocatalytic degradation of acetaminophen from 60.0 to 98.46% for 120 min.

10.
Nanotechnology ; 29(24): 245602, 2018 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-29582779

RESUMO

Here, we present a precise process for synthesizing Pd-Ag bimetallic nanoparticles (NPs) onto polymeric nanofibers by decorating Pd-NPs through atomic layer deposition followed by a chemical reduction process for tagging Ag nanostructures with bimetallic functionality. The results show that Pd-NPs act as a nucleation platform for tagging Ag and form Pd-Ag bimetallic NPs with a monodisperse nature with significant catalytic enhancement to the reaction rate over the bimetallic nature of the Pd-Ag ratio. A Pd-NP decorated polymeric nanofibrous web acts as an excellent platform for the encapsulation or interaction of Ag, which prevents agglomeration and promotes the interaction of Ag ions only on the surface of the Pd-NPs. We observed an effective reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4) to access the catalytic activity of Pd-Ag bimetallic NPs on a free-standing flexible polymeric nanofibrous web as a support. The captive formation of the polymeric nanofibrous web with Pd-Ag bimetallic functionality exhibited superior and stable catalytic performance with reduction rates of 0.0719, 0.1520, and 0.0871 min-1 for different loadings of Ag on Pd decorated nanofibrous webs such as Pd/Ag(0.01), Pd/Ag(0.03), and Pd/Ag(0.05), respectively. The highly faceted Pd-Ag NPs with an immobilized nature improves the catalytic functionality by enhancing the binding energy of the 4-NP adsorbate to the surface of the NPs. With the aid of bimetallic functionality, the nanofibrous web was demonstrated as a hybrid heterogeneous photocatalyst with a 3.16-fold enhancement in the reaction rate as compared with the monometallic decorative nature of NaBH4 as a reducing agent. The effective role of the monodisperse nature of Pd ions with an ultralow content as low as 3 wt% and the tunable ratio of Ag on the nanofibrous web induced effective catalytic activity over multiple cycles.

11.
Sci Rep ; 7(1): 13401, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-29042622

RESUMO

Coupling the functional nanoheterostructures over the flexible polymeric nanofibrous membranes through electrospinning followed by the atomic layer deposition (ALD), here we presented a high surface area platform as flexible and reusable heterogeneous nanocatalysts. Here, we show the ALD of titanium dioxide (TiO2) protective nanolayer onto the electrospun polyacrylonitrile (PAN) nanofibrous web and then platinum nanoparticles (Pt-NP) decoration was performed by ALD onto TiO2 coated PAN nanofibers. The free-standing and flexible Pt-NP/TiO2-PAN nanofibrous web showed the enhancive reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 45 seconds though the hydrogenation process with the degradation rate of 0.1102 s-1. The TiO2 protective layer on the PAN polymeric nanofibers was presented as an effective route to enhance the attachment of Pt-NP and to improve the structure stability of polymeric nanofibrous substrate. Commendable enhancement in the catalytic activity with the catalytic dosage and the durability after the reusing cycles were investigated over the reduction of 4-NP. Even after multiple usage, the Pt-NP/TiO2-PAN nanofibrous webs were stable with the flexible nature with the presence of Pt and TiO2 on its surface.

12.
Sci Rep ; 7(1): 3251, 2017 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-28607353

RESUMO

Tailoring the surface properties by varying the chemistry and roughness could be of interest for self-cleaning applications. We demonstrate the transformation of hydrophobic ZnO Nano rod (NR) array into superhydrophobic nature by changing the local chemical state and without altering the surface roughness by swift heavy ion (SHI) irradiation. The aligned ZnO NR arrays were irradiated using 150 MeV Ag ions with different fluences from 5E10 to 3E12 ions/cm2. The observed static water contact angles of ZnO NRs samples were 103° ± 3°, 152° ± 4°,161° ± 3°, 164° ± 2°, 167° ± 2°,154 ± 3° and 151° ± 2° for the pristine, ion fluencies of 1E11, 3E11, 5E11, 7E11, 1E12 and 3E12 ions cm-2, respectively. The change in local surface chemistry via formation of surface oxygen related defects due to electronic excitations induced by ion irradiation determine the water dewetting properties. It is found that surface oxygen related defects could be tuned by varying the fluence of the SHIs. Durability tests show that the SHI induced surface oxygen-deficient ZnO NRs have the stable superhydrophobic behavior for more than a year.

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