Correlation between Structural Changes and Electrical Transport Properties of Spinel ZnFe2O4 Nanoparticles under High Pressure

Electron and ion transport behavior of Vanadium based MXene induced by pressure for Lithium ion intercalated electrodes

Pressure, analogous with temperature and composition, is other meaningful variant for tuning the structure-activity properties of layered materials. In-situ high-pressure electrical results discover that Vanadium based MXene (V₂CT_x MXene) conductivity is increased by one order of magnitude from ambient to 10.4 GPa, and then the conductivity is still fixated on meeting growth as pressure releasing. Increased carrier concentration due to denser compactness is the most important factor in improving sample conductivity. Furthermore, abundant of V₂CT_x samples after preloading different pressures are prepared by the mean of the double-anvil hydraulic press for the first time, and results of increased conductivity were reproduced at ambient conditions. The first-principles calculation of V₂C (non-functional group), V₂CF, V₂CO, and V₂COH explains for the lattice expansion by tracing emotion of different function groups upon decompression. Electrochemical results obtain that once forming V₂CT_x MXene anode rapidly quenched from 2.0 GPa in hydraulic press shows better performance, obviously weakening electric polarization and increasing Li-ion transport rate due to its proper interlaminar densification and improved conductivity. This work opens up a new, simple, and universal approach to develop MXene materials with superior electrical and electrochemical properties, as well as expanding the potential applications for energy storage.

Pressure-Engineered Ti3C2Tx MXene with Enhanced Conductivity and Accelerated Reaction Kinetics of Lithium Storage

We studied the structure-function relationship of compressed Ti₃C₂T_x MXene using high-pressure in situ synchrotron radiation, impedance spectroscopy, Hall effect measurements, and first-principles calculations. With increasing pressure, the conductivity of Ti₃C₂T_x MXene increases along with its continued lattice shrinkage. A pressure range of 0.4-2.2 GPa exhibits a sharp decrease in resistance, which decreases by more than one order of magnitude from 3.3 × 10⁴ to 1.4 × 10³ Ω. A pressure range of 2.2-6.6 GPa exhibits a steady resistance with a slight decrease of 0.2%. As the pressure drops to atmospheric conditions, the resistance increases slightly to 4.2 × 10³ Ω. This is accompanied by a transformation of the semiconductor into metal. An irreversible increase in conductivity is observed owing to an increase in the electron concentration and a decrease in the grain-boundary potential barrier. Furthermore, abundant Ti₃C₂T_x undergoing prepressure treatments (0.4, 2.0, and 4.0 GPa) was first prepared using a double-anvil hydraulic press. The recycled samples retain an accordion-like layered structure with slight lattice shrinkage while the voids between the sheets contract considerably, increasing the density. Correspondingly, electrochemical results show a pressure threshold of 2.0 GPa based on the rapid quenching from the hydraulic press. This weakens the electric polarization in redox reactions and increases the ionic transport rate for the formation of a Ti₃C₂T_x anode owing to pressure improving the conductivity and interlaminar densification. Our study shows a new, simple, and universal way to regulate various MXenes and also promotes the application of MXene-based materials in energy storage and related fields.

Superparamagnetic ZnFe2O4 Nanoparticles-Reduced Graphene Oxide-Polyurethane Resin Based Nanocomposites for Electromagnetic Interference Shielding Application

Superparamagnetic ZnFe2O4 spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe2O4 spinel ferrite nanoparticles were controlled via sonochemical synthesis time. The average crystallite size increases from 3.0 nm to 4.0 nm with a rise of sonication time from 25 min to 100 min. The change of physical properties of ZnFe2O4 nanoparticles with the increase of sonication time was observed. The prepared ZnFe2O4 nanoparticles show superparamagnetic behavior. The prepared ZnFe2O4 nanoparticles (ZS25, ZS50, and ZS100) and reduced graphene oxide (RGO) were embedded in a polyurethane resin (PUR) matrix as a shield against electromagnetic pollution. The ultra-sonication method has been used for the preparation of nanocomposites. The total shielding effectiveness (SET) value for the prepared nanocomposites was studied at a thickness of 1 mm in the range of 8.2-12.4 GHz. The high attenuation constant (α) value of the prepared ZS100-RGO-PUR nanocomposite as compared with other samples recommended high absorption of electromagnetic waves. The existence of electric-magnetic nanofillers in the resin matrix delivered the inclusive acts of magnetic loss, dielectric loss, appropriate attenuation constant, and effective impedance matching. The synergistic effect of ZnFe2O4 and RGO in the PUR matrix led to high interfacial polarization and, consequently, significant absorption of the electromagnetic waves. The outcomes and methods also assure an inventive and competent approach to develop lightweight and flexible polyurethane resin matrix-based nanocomposites, consisting of superparamagnetic zinc ferrite nanoparticles and reduced graphene oxide as a shield against electromagnetic pollution.

Ultrasensitive detection of protein biomarkers by MALDI-TOF mass spectrometry based on ZnFe2O4 nanoparticles and mass tagging signal amplification

A facile MALDI-TOF mass spectrometric platform for quantitative analysis of protein biomarkers was developed based on magnetic ZnFe₂O₄ nanoparticles and mass tagging signal amplification. In this platform, magnetic ZnFe₂O₄ nanoparticles functionalized with an aptamer of the biomarker of interest was used to magnetically separate silica nanoparticles modified with another aptamer of the target biomarker and a barcoding peptide from solution phase in the presence of the biomarker of interest. After the silica nanoparticles were dissolved by KHF₂, the released barcoding peptide was detected by MALDI-TOF mass spectrometry with magnetic ZnFe₂O₄ nanoparticles used as assisting matrix of laser desorption ionization. Since the mass spectral intensity of the barcoding peptide is directly related to the concentration of the target biomarker, the proposed platform can be applied to the quantification of the target biomarker in complex biological samples. The effectiveness of the proposed platform was tested on the detection of carcinoembryonic antigen (CEA) in serum. Experimental results revealed that the proposed platform could achieve quite reliable quantitative results for CEA in human serum samples with accuracy comparable to a commercial CEA ELISA Kit. Its limit of detection and limit of quantification for CEA were estimated to be 0.6 × 10^-3 and 1.8 × 10^-3 ng/mL, respectively, considerably lower than the corresponding values reported in literature. Due to its features of simplicity in design, extremely low background signal, high sensitivity and selectivity, the proposed method can be further developed to be a competitive alternative for the quantification of CEA and other protein biomarkers as well.

NiFe2O4 Nanoparticles Synthesized by Dextrin from Corn-Mediated Sol-Gel Combustion Method and Its Polypropylene Nanocomposites Engineered with Reduced Graphene Oxide for the Reduction of Electromagnetic Pollution

In this work, nickel ferrite (NiFe2O4) nanoparticles were synthesized by dextrin from corn-mediated sol-gel combustion method and were annealed at 600, 800, and 1000 °C. The structural and physical characteristics of prepared nanoparticles were studied in detail. The average crystallite size was 20.6, 34.5, and 68.6 nm for NiFe2O4 nanoparticles annealed at 600 °C (NFD@600), 800 °C (NFD@800), and 1000 °C (NFD@1000), respectively. The electromagnetic interference shielding performance of prepared nanocomposites of NiFe2O4 nanoparticles (NFD@600 or NFD@800 or NFD@1000) in polypropylene (PP) matrix engineered with reduced graphene oxide (rGO) have been investigated; the results indicated that the prepared nanocomposites consisted of smaller-sized nickel ferrite nanoparticles exhibited excellent electromagnetic interference (EMI) shielding characteristics. The total EMI shielding effectiveness (SET) for the prepared nanocomposites have been noticed to be 45.56, 36.43, and 35.71 dB for NFD@600-rGO-PP, NFD@800-rGO-PP, and NFD@1000-rGO-PP nanocomposites, respectively, at the thickness of 2 mm in microwave X-band range (8.2-12.4 GHz). The evaluated values of specific EMI shielding effectiveness (SSE) were 38.81, 32.79, and 31.73 dB·cm3/g, and the absolute EMI shielding effectiveness (SSE/t) values were 388.1, 327.9, and 317.3 dB·cm2/g for NFD@600-rGO-PP, NFD@800-rGO-PP, and NFD@1000-rGO-PP, respectively. The prepared lightweight and flexible sheets can be considered useful nanocomposites against electromagnetic radiation pollution.

Tunable photoluminescence and an enhanced photoelectric response of Mn2+-doped CsPbCl3 perovskite nanocrystals via pressure-induced structure evolution

Mn²⁺:CsPbCl₃ nanocrystals (NCs) were synthesized using a modified one-pot injection method, which exhibits significantly improved thermal stability. For the first time, the pressure-treated optical and structural properties of synthetic Mn²⁺:CsPbCl₃ NCs were further investigated, and their associated intriguing electrical and photoelectric properties were revealed from impedance spectra and photocurrent measurements under compression. The pressure-dependent photoluminescence experienced an initial redshift before 1.7 GPa followed by a continuous blueshift, as evidenced by the bandgap shifts. High-pressure XRD spectra uncovered a cubic-to-orthorhombic structural transition at about 1.1 GPa and subsequent amorphization upon further compression, which was fully reversible. Furthermore, the sample annealing from 340 K drove grain growth and decreased grain boundary resistance at ambient pressure. The compression further decreased the grain boundary barrier and improved the electrical conductivity (up to ∼10^-2Ω^-1 cm^-1) of the thermally annealed Mn²⁺:CsPbCl₃ NC surface. Simultaneous photocurrent enhancement of thermally annealed NCs was also achieved as expected, and reached optimal performance at 0.7 GPa. Strikingly, after the pressure cycling (loading-releasing), the results show that thermally annealed Mn²⁺:CsPbCl₃ NCs gained preservable higher electrical conductivity (∼10 times increase) and an improved photoelectric response compared to the ambient state before compression. This work proves that high pressure is useful for opening the versatility in the structure and properties of metal-halide perovskite nanocrystals leading to a promising way for superior optoelectronic materials-by-design.