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1.
Small ; 20(4): e2304483, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37730973

ABSTRACT

MXenes are a class of 2D materials that include layered transition metal carbides, nitrides, and carbonitrides. Since their inception in 2011, they have garnered significant attention due to their diverse compositions, unique structures, and extraordinary properties, such as high specific surface areas and excellent electrical conductivity. This versatility has opened up immense potential in various fields, catalyzing a surge in MXene research and leading to note worthy advancements. This review offers an in-depth overview of the evolution of MXenes over the past 5 years, with an emphasis on synthetic strategies, structure-property relationships, and technological prospects. A classification scheme for MXene structures based on entropy is presented and an updated summary of the elemental constituents of the MXene family is provided, as documented in recent literature. Delving into the microscopic structure and synthesis routes, the intricate structure-property relationships are explored at the nano/micro level that dictate the macroscopic applications of MXenes. Through an extensive review of the latest representative works, the utilization of MXenes in energy, environmental, electronic, and biomedical fields is showcased, offering a glimpse into the current technological bottlenecks, such asstability, scalability, and device integration. Moreover, potential pathways for advancing MXenes toward next-generation technologies are highlighted.

2.
Small ; 20(19): e2309249, 2024 May.
Article in English | MEDLINE | ID: mdl-38152975

ABSTRACT

Achieving a balance between H-atom adsorption and binding with H2 desorption is crucial for catalyzing hydrogen evolution reaction (HER). In this study, the feasibility of designing and implementing built-in opposite electric fields (OEF) is demonstrated to enable optimal H atom adsorption and H2 desorption using the Ni3(BO3)2/Ni5P4 heterostructure as an example. Through density functional theory calculations of planar averaged potentials, it shows that opposite combinations of inward and outward electric fields can be achieved at the interface of Ni3(BO3)2/Ni5P4, leading to the optimization of the H adsorption free energy (ΔGH*) near electric neutrality (0.05 eV). Based on this OEF concept, the study experimentally validated the Ni3(BO3)2/Ni5P4 system electrochemically forming Ni3(BO3)2 through cyclic voltammetry scanning of B-doped Ni5P4. The surface of Ni3(BO3)2 undergoes reconstruction, as characterized by Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) and in situ Raman spectroscopy. The resulting catalyst exhibits excellent HER activity in alkaline media, with a low overpotential of 33 mV at 10 mA cm-2 and stability maintained for over 360 h. Therefore, the design strategy of build-in opposite electric field enables the development of high-performance HER catalysts and presents a promising approach for electrocatalyst advancement.

3.
Phys Chem Chem Phys ; 26(9): 7896-7906, 2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38376501

ABSTRACT

Metallene materials can provide a large number of active catalytic sites for the efficient use of noble metals as catalysts for hydrogen evolution reaction (HER), whereas the intrinsic activity on the surface is insufficient in crystal phase. The amorphous phase with an inherent long-range disorder can offer a rich coordinate environment and charge polarization on the surface is proposed for promoting the intrinsic catalytic activity on the surface of noble metals. Herein, we designed an amorphous RuPd (am-RuPd) structure by the first principles molecular dynamics method. The performance of the acidic HER on am-RuPd can have a huge enhancement due to the free energy change of hydrogen adsorption close to zero. In alkaline conditions, the H2O dissociation energy barrier on am-RuPd is just 0.49 eV, and it is predicted that the alkaline HER performance of am-RuPd will largely exceed that of Pt nanocrystalline sheets. This work provides a strategy for enhancing the intrinsic catalytic activity on the surface and a way to design an efficient HER catalyst based on metallene materials used in both acidic and alkaline conditions.

4.
Nano Lett ; 23(20): 9555-9562, 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37787483

ABSTRACT

The effective design and construction of high-performance methanol oxidation reaction (MOR) electrocatalysts are significant for the development of direct methanol fuel cells. But the active sites of the MOR electrocatalysts are susceptible to being poisoned by CO, resulting in poor durability. Herein, we report an atomically dispersed CrOX species anchored on Pd metallene through bridging O atoms. This catalyst shows an outstanding MOR performance with 7 times higher mass activity and 100 mV lower CO electrooxidation potential than commercial Pd/C. The results of operando electrochemical Fourier transform infrared spectroscopy demonstrate the rapid removal of CO* on CrOX-Pd metallene. Theoretical calculations reveal that atomically dispersed CrOX can lower the adsorption energy of CO* on Pd sites and enhance that of OH* through the formation of a hydrogen bond, decreasing the formation energy of COOH*. This work provides a new strategy for improving MOR performance via atomically engineering oxide/metal interfaces.

5.
Angew Chem Int Ed Engl ; 63(15): e202400765, 2024 Apr 08.
Article in English | MEDLINE | ID: mdl-38349119

ABSTRACT

Metal single-atom catalysts represent one of the most promising non-noble metal catalysts for the oxygen reduction reaction (ORR). However, they still suffer from insufficient activity and, particularly, durability for practical applications. Leveraging density functional theory (DFT) and machine learning (ML), we unravel an unexpected collective effect between FeN4OH sites, CeN4OH motifs, Fe nanoparticles (NPs), and Fe-CeO2 NPs. The collective effect comprises differently-weighted electronic and geometric interactions, whitch results in significantly enhanced ORR activity for FeN4OH active sites with a half-wave potential (E1/2) of 0.948 V versus the reversible hydrogen electrode (VRHE) in alkaline, relative to a commercial Pt/C (E1/2, 0.851 VRHE). Meanwhile, this collective effect endows the shortened Fe-N bonds and the remarkable durability with negligible activity loss after 50,000 potential cycles. The ML was used to understand the intricate geometric and electronic interactions in collective effect and reveal the intrinsic descriptors to account for the enhanced ORR performance. The universality of collective effect was demonstrated effective for the Co, Ni, Cu, Cr, and Mn-based multicomponent ensembles. These results confirm the importance of collective effect to simultaneously improve catalytic activity and durability.

6.
Angew Chem Int Ed Engl ; 63(6): e202318246, 2024 Feb 05.
Article in English | MEDLINE | ID: mdl-38102742

ABSTRACT

Addressing the limitations arising from the consistent catalytic behavior observed for various intermediates during the electrochemical carbon dioxide reduction reaction (CO2 RR) poses a significant challenge in the optimization of catalytic activity. In this study, we aimed to address this challenge by constructing an asymmetric coordination Fe single atom catalyst (SCA) with a dynamically evolved structure. Our catalyst, consisting of a Fe atom coordinated with one S atom and three N atoms (Fe-S1 N3 ), exhibited exceptional selectivity (CO Faradaic efficiency of 99.02 %) and demonstrated a high intrinsic activity (TOF of 7804.34 h-1 ), and remarkable stability. Using operando XAFS spectra and Density Functional Theory (DFT) calculations, we elucidated the self-relaxation of geometric distortion and dynamic evolution of bond lengths within the catalyst. These structure changes enabled independent regulation of the *COOH and *CO intermediate adsorption energies, effectively breaking the linear scale relationship and enhancing the intrinsic activity of CO2 RR. This study provides valuable insights into the dynamic evolution of SACs and paves the way for targeted catalyst designs aimed to disrupt the linear scaling relationships.

7.
Angew Chem Int Ed Engl ; 63(24): e202403203, 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38590293

ABSTRACT

Nanozymes have demonstrated significant potential in combating malignant tumor proliferation through catalytic therapy. However, the therapeutic effect is often limited by insufficient catalytic performance. In this study, we propose the utilization of strain engineering in metallenes to fully expose the active regions due to their ultrathin nature. Here, we present the first report on a novel tensile strain-mediated local amorphous RhRu (la-RhRu) bimetallene with exceptional intrinsic photothermal effect and photo-enhanced multiple enzyme-like activities. Through geometric phase analysis, electron diffraction profile, and X-ray diffraction, it is revealed that crystalline-amorphous heterophase boundaries can generate approximately 2 % tensile strain in the bimetallene. The ultrathin structure and in-plane strain of the bimetallene induce an amplified strain effect. Both experimental and theoretical evidence support the notion that tensile strain promotes multiple enzyme-like activities. Functioning as a tumor microenvironment (TME)-responsive nanozyme, la-RhRu exhibits remarkable therapeutic efficacy both in vitro and in vivo. This work highlights the tremendous potential of atomic-scale tensile strain engineering strategy in enhancing tumor catalytic therapy.


Subject(s)
Photothermal Therapy , Humans , Catalysis , Animals , Mice , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Neoplasms/drug therapy , Neoplasms/therapy , Tensile Strength , Cell Line, Tumor , Tumor Microenvironment/drug effects
8.
J Am Chem Soc ; 145(10): 5710-5717, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36877096

ABSTRACT

Hydride metallenes show great potential for hydrogen-related catalytic applications due to favorable electronic structures modulated by interstitial hydrogen atoms and large active surface areas of metallenes. Metallene nanostructures generally have compressive strain relative to bulk, which can affect both the stability and the catalytic behavior of hydride metallenes but in general cannot be controlled. Here, we demonstrate highly stable PdHx metallenes with a tensile strained Ru surface layer and reveal the spatial confinement effect of the Ru skin by multiple spectroscopic characterizations and molecular dynamics simulations. These PdHx@Ru metallenes with a 4.5% expanded Ru outer layer exhibit outstanding alkaline hydrogen evolution reaction activity with a low overpotential of 30 mV at 10 mA cm-2 and robust stability with negligible activity decay after 10,000 cycles, which are superior to commercial Pt/C and most reported Ru-based electrocatalysts. Control experiments and first-principles calculations reveal that the tensile strained Ru outer layer lowers the energy barrier of H2O dissociation and provides a moderate hydrogen adsorption energy.

9.
J Am Chem Soc ; 145(25): 14133-14142, 2023 Jun 28.
Article in English | MEDLINE | ID: mdl-37317545

ABSTRACT

Electrocatalytic reduction of carbon dioxide into value-added chemical fuels is a promising way to achieve carbon neutrality. Bismuth-based materials have been considered as favorable electrocatalysts for converting carbon dioxide to formic acid. Moreover, size-dependent catalysis offers significant advantages in catalyzed heterogeneous chemical processes. However, the size effects of bismuth nanoparticles on formic acid production have not been fully explored. Here, we prepared Bi nanoparticles uniformly supported on porous TiO2 substrate electrocatalytic materials by in situ segregation of the Bi element from Bi4Ti3O12. The Bi-TiO2 electrocatalyst with Bi nanoparticles of 2.83 nm displays a Faradaic efficiency of greater than 90% over a wide potential range of 400 mV. Theoretical calculations have also demonstrated subtle electronic structural evolutions induced by the size variations of Bi nanoparticles, where the 2.83 nm Bi nanoparticles display the most active p-band and d-band centers to guarantee high electroactivity toward CO2RR.

10.
Small ; 19(17): e2207332, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36719997

ABSTRACT

Delicate electrochemical active surface area (ECSA) engineering over the exposed catalytic interface and surface topology of platinum-based nanomaterial represents an effective pathway to boost its catalytic properties toward the clean energy conversion system. Here, for the first time, the facial and universal production of dendritic Pt-based nanoalloys (Pt-Ni, Co, Fe) with highly porous feature via a novel Zn2+ -mediated solution approach is demonstrated. In the presence of Zn2+ during synthesis, the competition of different galvanic replacement reactions and consequently generated "branch-to-branch" growth mode are believed to play key roles for the in situ fabrication of such unique nanostructure. Due to the fully exposed active sites and ligand effect-induced electronic optimization, electrochemical hydrogen evolution in alkaline media on these catalysts exhibit dramatic activity enhancement, delivering a current density of 30.6 mA cm-2 at a 70 mV overpotential for the Pt3 Ni nanodendrites and over 7.4 times higher than that of commercial Pt/C. This work highlights a general and powerful ion-assisted strategy for exploiting dendritic Pt-based nanostructures with efficient activities for water electrolysis.

11.
Chem Biodivers ; 20(9): e202300986, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37559110

ABSTRACT

Asparagus officinalis is a health-care vegetable with homology value of medicine and food. The quality of A. officinalis is greatly different from various cultivars. It is essential to reveal the relationship between the variety and quality. This study investigated six nutritional compositions in ten A. officinalis cultivars, including amino acid, mineral substance, carbohydrate, vitamin C, protein and total sugar. Five chemometrics methods were further employed to evaluate their quality. The results consistently showed that ten varieties were divided into three grades as nutritional composition differences. HuaMiaoF1, JinGuan and FeiCuiMingZhu were grouped into cluster3 with the best quality, and Atlas and Jersey Giant were grouped into cluster1 with the lowest quality. Therefore, HuaMiaoF1, JinGuan and FeiCuiMingZhu can be suggested as good raw materials for medicine, food and health-care products industries. Meanwhile, the comprehensive application of five chemometrics methods was confirmed as a reliable methodology for quality evaluation of A. officinalis.


Subject(s)
Asparagus Plant , Asparagus Plant/chemistry , Functional Food , Ascorbic Acid
12.
Angew Chem Int Ed Engl ; 62(15): e202300119, 2023 04 03.
Article in English | MEDLINE | ID: mdl-36780128

ABSTRACT

Single-atom nanozymes (SAzymes) are promising in next-generation nanozymes, nevertheless, how to rationally modulate the microenvironment of SAzymes with controllable multi-enzyme properties is still challenging. Herein, we systematically investigate the relationship between atomic configuration and multi-enzymatic performances. The constructed MnSA -N3 -coordinated SAzymes (MnSA -N3 -C) exhibits much more remarkable oxidase-, peroxidase-, and glutathione oxidase-like activities than that of MnSA -N4 -C. Based on experimental and theoretical results, these multi-enzyme-like behaviors are highly dependent on the coordination number of single atomic Mn sites by local charge polarization. As a consequence, a series of colorimetric biosensing platforms based on MnSA -N3 -C SAzymes is successfully built for specific recognition of biological molecules. These findings provide atomic-level insight into the microenvironment of nanozymes, promoting rational design of other demanding biocatalysts.


Subject(s)
Biosensing Techniques , Manganese , Colorimetry , Carbon , Peroxidases , Peroxidase , Catalysis
13.
Ecotoxicol Environ Saf ; 234: 113418, 2022 Apr 01.
Article in English | MEDLINE | ID: mdl-35304336

ABSTRACT

Introduction of antibiotics into agricultural fields poses serious health risks to humans. This study investigated the uptake of antibiotics, their effects on metabolic pathways, and chloroplast structure changes of Allium tuberosum exposed to norfloxacin (NFL), oxytetracycline (OTC), and tetracycline (TC). Among all the antibiotic treatments, the highest accumulation of antibiotics in roots (4.15 mg/kg) and leaves (0.29 mg/kg) was TC, while in bulbs it was NFL (5.94 mg/kg). OTC was with the lowest accumulation in roots: 0.19 mg/kg, bulbs: 0.18 mg/kg, and leaves: 0.11 mg/kg. The number of mitochondira and the number of plastoglobulli increased. The chloroplast structure was disturbed under the stress of NFL, OTC, and TC. Disturbance in the chloroplast ultrastructure leads to altered chlorophyll fluorescence variables. Simultaneously, metabolomic profiling of leaves demonstrated that NFL stress regulated more of metabolic pathways than OTC and TC. Differences in metabolic pathways among the antibiotic treatments showed that each antibiotic has different impact even under the same experimental conditions. TC and NFL have more toxic effects than OTC antibiotic. Metabolic variations induced by antibiotics stress highlighted pools of metabolites that affect the metabolic activities, chlorophyll fluorescence, ultrastructural adjustments, and stimulate defensive impact in A. tubersoum. These findings provide an insight of metabolic destabilization as well as metabolic changes in defensive mechanism and stress response of A. tuberosum to different antibiotics.

14.
Angew Chem Int Ed Engl ; 61(34): e202207512, 2022 Aug 22.
Article in English | MEDLINE | ID: mdl-35762984

ABSTRACT

Accelerating slow water dissociation kinetics is key to boosting the hydrogen evolution reaction (HER) in alkaline media. We report the synthesis of atomically dispersed MoOx species anchored on Rh metallene using a one-pot solvothermal method. The resulting structures expose the oxide-metal interfaces to the maximum extent. This leads to a MoOx -Rh catalyst with ultrahigh alkaline HER activity. We obtained a mass activity of 2.32 A mgRh -1 at an overpotential of 50 mV, which is 11.8 times higher than that of commercial Pt/C and surpasses the previously reported Rh-based electrocatalysts. First-principles calculations demonstrate that the interface between MoOx and Rh is the active center for alkaline HER. The MoOx sites preferentially adsorb and dissociate water molecules, and adjacent Rh sites adsorb the generated atomic hydrogen for efficient H2 evolution. Our findings illustrate the potential of atomic interface engineering strategies in electrocatalysis.

15.
J Am Chem Soc ; 142(7): 3645-3651, 2020 Feb 19.
Article in English | MEDLINE | ID: mdl-32023049

ABSTRACT

The design of catalysts with high activity and robust stability for alkaline hydrogen evolution reaction (HER) remains a great challenge. Here, we report an efficient catalyst of two-dimensional bimetallene hydrides, in which H atoms stabilize the rhodium palladium bimetallene. The system exists because of the introduction of H that is in situ chemically released from the formaldehyde solution during the synthesis. This provides a highly stable catalyst based on an unstable combination of metal elements. Density functional theory calculations show the H is confined by electronic interactions and the Miedema rule of reverse stability of the RhPd alloy. The obtained catalyst exhibits outstanding alkaline HER catalytic performance with a low overpotential of 40 mV at 10 mA cm-2 and remarkable stability for over 10 h at 100 mA cm-2. The experimental results show that the confined H improve the activity, while the ultrathin sheet-like morphology yields stability. Our work provides guidance for synthesizing high-activity catalysts by confining heteroatoms into the crystal lattice of bimetallene and also a very novel mechanism for the growth of bimetallene made of highly immiscible components.

16.
Anal Chem ; 92(4): 3354-3360, 2020 02 18.
Article in English | MEDLINE | ID: mdl-32011882

ABSTRACT

Herein, we report on a two-dimensional amino-functionalized Ti3C2-MXene (N-Ti3C2-MXene)-based surface plasmon resonance (SPR) biosensor for detecting carcinoembryonic antigen (CEA) utilizing a sandwich format signal amplification strategy. Our biosensor employs an N-Ti3C2-MXene nanosheet-modified sensing platform and a signal enhancer comprising N-Ti3C2-MXene-hollow gold nanoparticles (HGNPs)-staphylococcal protein A (SPA) complexes. Ultrathin Ti3C2-MXene nanosheets were synthesized and functionalized with aminosilane to provide a hydrophilic-biocompatible nanoplatform for covalent immobilization of the monoclonal anti-CEA capture antibody (Ab1). The N-Ti3C2-MXene/HGNPs nanohybrids were synthesized and further decorated with SPA to immobilize the polyclonal anti-CEA detection antibody (Ab2) and serve as signal enhancers. The capture of CEA followed by the formation of the Ab2-conjugated SPA/HGNPs/N-Ti3C2-MXene sandwiched nanocomplex on the SPR chip results in the generation of a response signal. The fabricated N-Ti3C2-MXene-based SPR biosensor exhibited a linear detection range of 0.001-1000 PM with a detection limit of 0.15 fM. The proposed biosensor showed high sensitivity and specificity for CEA in serum samples, which gives it application potential in the early diagnosis and monitoring of cancer. We believe that this work also opens new avenues for development of MXene-based highly sensitive biosensors for determining various biomolecules.


Subject(s)
Carcinoembryonic Antigen/analysis , Nanoparticles/chemistry , Titanium/chemistry , Biosensing Techniques , Humans , Surface Plasmon Resonance
17.
Ecotoxicol Environ Saf ; 200: 110748, 2020 Sep 01.
Article in English | MEDLINE | ID: mdl-32470678

ABSTRACT

Cadmium (Cd) is an inauspicious abiotic traction that not only influences crop productivity and its growth parameters, but also has adverse effects on human health if these crops are consumed. Among crops, leafy vegetables which are the good source of mineral and vitamins accumulate more Cd than other vegetables. It is thus important to study photosynthetic variables, amino acid composition, and ultrastructural localization of Cd differences in response to Cd accumulation between two low and high Cd accumulating Brassica rapa ssp. chinensis L. (pak choi) cultivars, differing in Cd accumulation ability. Elevated Cd concentrations significantly lowered plant growth rate, biomass, leaf gas exchange and concentrations of amino acids collated to respective controls of both cultivars. Electron microscopy indicated that the impact of high Cd level on ultrastructure of leaf cells was associated to affecting cell functionalities, i.e. irregular cell wall, withdrawal of cell membrane, and chloroplast structure which has negative impact on photosynthetic activities, thus causing considerable plant growth suppression. Damage in root cells were observed in the form of enlargement of vacuole. The energy dispersive micro X-ray spectroscopy of both cultivars leaves indicated that cellular structure exhibited exudates of Cd-dense material. Ultrastructural damages and phytotoxicity were more pronounced in high accumulator cultivar as compared to the low accumulator cultivar. These findings are useful in determining the mechanisms of differential Cd-tolerance among cultivars with different Cd tolerance abilities at cellular level.


Subject(s)
Brassica rapa/drug effects , Brassica rapa/metabolism , Cadmium/toxicity , Amino Acids/analysis , Biomass , Brassica rapa/growth & development , Brassica rapa/ultrastructure , Cadmium/pharmacokinetics , Cell Wall/drug effects , Cell Wall/ultrastructure , Crops, Agricultural/drug effects , Crops, Agricultural/growth & development , Crops, Agricultural/metabolism , Humans , Photosynthesis/drug effects , Plant Leaves/drug effects , Plant Leaves/metabolism , Plant Leaves/ultrastructure
18.
Nano Lett ; 19(5): 2758-2764, 2019 05 08.
Article in English | MEDLINE | ID: mdl-30958673

ABSTRACT

Metallic 1T-phase transition metal dichalcogenides (TMDs) are of considerable interest in enhancing catalytic applications due to their abundant active sites and good conductivity. However, the unstable nature of 1T-phase TMDs greatly impedes their practical applications. Herein, we developed a new approach for the synthesis of highly stable 1T-phase Au/Pd-MoS2 nanosheets (NSs) through a metal assembly induced ultrastable phase transition for achieving a very high electrocatalytic activity in the hydrogen evolution reaction. The phase transition was evoked by a novel mechanism of lattice-mismatch-induced strain based on density functional theory (DFT) calculations. Raman spectroscopy and transmission electron microscopy (TEM) were used to confirm the phase transition on experimental grounds. A novel heterostructured 1T MoS2-Au/Pd catalyst was designed and synthesized using this mechanism, and the catalyst exhibited a 0 mV onset potential in the hydrogen evolution reaction under light illumination. Therefore, this method can potentially be used to fabricate 1T-phase TMDs with remarkably enhanced activities for different applications.

19.
Inorg Chem ; 58(4): 2315-2329, 2019 Feb 18.
Article in English | MEDLINE | ID: mdl-30706716

ABSTRACT

Crystallization of perovskite structure chromites (ACrO3) in aqueous conditions is difficult owing to the amphoteric nature of the Cr3+ in the alkaline-mediated reaction conditions. This is especially true for the small metal cations at the A-site with large distortion angle of CrO6 octahedral and small Goldschmidt tolerance factors. Here, we performed a progressive dehydration crystallization strategy to synthesize four RECrO3 with the smallest radii of rare earth elements (Er, Tm, Yb, Lu) in mild hydrothermal conditions. Profile refinement of the high-resolution powder X-ray diffraction results indicated slightly longer unit cell parameters of  a and c in our samples with a higher distorted angle of CrO6 octahedral units along ⟨010⟩ direction. All of the samples show rounded rectangle plate morphology with uniform distribution of particle sizes. These four RECrO3 crystals can only form in a very narrow mineralization temperature range, i.e., 260-280 °C and 4.45-6.24 M of KOH. HRTEM results indicated that the normal crystallographic direction is ⟨001⟩, and the lattice of steps at the edge of elliptic rounded crystal is consistent with the bulk, which demonstrated single crystalline nature of the as-obtained crystals. Room-temperature Raman and FT-IR spectra reveal a continuous symmetry mode shift-dependent on the radii of A-site rare-earth cations. Temperature-dependent magnetization curves of RECrO3 show typical antiferromagnetism to paramagnetism transition with Néel temperature of 93, 90, 86, and 83 K for ErCrO3, TmCrO3, YbCrO3, and LuCrO3, respectively. Samples of YbCrO3 and LuCrO3 show clear magnetization reversal and exchange bias phenomena below their Néel points. This paper indicates that the coupling of magnetic exchange in perovskite structure oxides could be tailorable in mild hydrothermal condition, towards the exploration of new magnetic and other physical properties.

20.
J Environ Manage ; 243: 144-156, 2019 Aug 01.
Article in English | MEDLINE | ID: mdl-31100659

ABSTRACT

Sewage sludge and kitchen refuse are ubiquitously mounting wastes with high organic load, which if reprocessed they could salvage the environment. Reckoned with this certitude, an incubating study was initiated on sequential preincubation of sewage sludge with kitchen waste in 100:0, 70:30, 50:50, and 30:70 ratios for 16 days ensued by vermicomposting of 30 days using Eisenia fetida. Concentration of heavy metals (Cd, Cr, Cu, Mn, Pb, and Zn) in the biosolid mixtures increased during preincubation but reduced progressively through vermicomposting due to bioaccumulation of these metals in the earthworm tissues. Earthworm growth parameters data reflected that sewage sludge and kitchen waste mixture with 70:30 ratio increased the number of cocoons (10.6%), biomass (8.2%), growth rate (8.3%), reproduction rate (12.2%), and decreased their mean mortality rate (80.1%) as compared to that in sole sewage sludge (control). Results of chemical analysis and SEM/EDS imaging, showed that alkalinity, organic carbon, C/N ratio, organic matter and concentration of trace elements (Cd, Cr, Cu, Mn, Pb, and Zn) reduced while macronutrients (N, P, K, Ca and Mg) increased in the final vermicompost as compared to that in initial mixtures. The FT-IR analysis also revealed that various biochemical functional groups underwent biodegradation during combined preincubation-vermicomposting. Bioaccumulation factor (BAF) of all trace elements in the earthworm tissues was higher with 70:30 ratio of substrates, with the trend of Cd > Zn > Cu > Mn > Pb > Cr. Hence, this study concludes that combined preincubation-vermicomposting is the most efficient and ecofriendly technique for biodegradation, stabilization, and conversion of sewage sludge and kitchen waste into organic fertilizer. The nutrient rich vermicompost can be safely used as horticultural substrate and soil conditioner for efficient management of degraded soils. Finally, combined preincubation-vermicomposting is a sustainable system of recycling the sewage sludge along with kitchen waste.


Subject(s)
Metals, Heavy , Oligochaeta , Animals , Sewage , Soil , Spectroscopy, Fourier Transform Infrared
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