Effect of vanadium on the room temperature ferromagnetism of V-doped 6H-SiC powder

This study focuses on the effect of V-doping on the ferromagnetism（FM） of 6H-SiC powder.The X-ray diffraction results indicate that V is inserted into the 6H-SiC lattice.The Raman spectra reveal that with a V concentration of 25 ppm,the crystalline quality and carrier concentration of 6H-SiC are hardly varied.It is found that after the V-doping process,the saturation magnetization（Ms） and the vacancy concentration of 6H-SiC are both increased.From these results,it is deduced that the effect of V might contribute mainly to the increase of vacancy concentration,thus resulting in the increase of Ms of V-doped 6H-SiC.

Defects mediated ferromagnetism in a V-doped 6H-SiC single crystal

Undoped and V-doped 6H-SiC single crystals have been grown by the physical vapor transport method.The V concentration is determined to be 3.76×10^17 at/cm^3 and 6.14×10^17 at/cm^3 by secondary ion mass spectrometry for low V-doped and high V-doped SiC samples,respectively.The undoped 6H-SiC shows diamagnetism,while the V-doped 6H-SiC exhibits weak ferromagnetism.The lower V-doped sample shows stronger ferromagnetism compared to that of the higher V-doped sample.However,the structural characterization indicates that the lower V-doped SiC has a relative poor crystalline quality.It is found that both V dopants and defects are essential for introducing ferromagnetic exchange in V-doped SiC single crystals.

Synthesis and Catalytic Performance of a New V-doped CeO_(2)-supported Alkali-activated-steel-slag-based Photocatalyst

A novel V-doped CeO_(2)-supported alkali-activated-steel-slag-based catalyst(V-CeO_(2)/AC)for photocatalytic decomposition of water to hydrogen was prepared via co-impregnation method.The chemical composition,mineral phase,morphology,and optical performances of the synthesized catalyst samples were characterized by XRF,XRD,SEM,UV-Vis DRS,and so on.XRD and SEM results show that calcium silicate hydrate(Ca1.5SiO3.5·xH2O)mineral phase is formed in the carrier sample,and the prepared catalyst specimens are made up of approximately 50 nm particles.After 6 hours of xenon lamp irradiation,the catalyst supported on V-doped 8wt%CeO_(2) exhibits the highest photocatalytic hydrogen production activity(8292μmol/g),which is attributed to the interaction between the V-doped CeO_(2) active components and FeO existed in catalyst carrier.A possible photocatalytic decomposition of water for hydrogen production mechanism over the V-8CeO_(2)/AC catalyst was proposed.

Mesoporous V-doped TiO_2 Nanoparticles as New Adsorbents for the Removal of Methylene Blue from Color Textile Wastewater

V-doped TiO2 nanoparticles（NPs） as dye adsorbents are synthesized by the co-precipitation method and characterized by X-ray powder diffraction, transmission electron microscope, N2 adsorption at 77 K, and X-ray photoelectron spectroscopy. The adsorption of methylene blue（MB） on the V-doped TiO2 NPs is studied in detail by varying the calcination temperature and V doping amount of the adsorbent, adsorbate concentration, adsorbent dosage, agitation rate, reaction temperature, and p H. The comparison of dye adsorption on V-doped TiO2 and parent TiO2 demonstrates that the adsorptive activity of TiO2 can be improved by V doping. The enhanced adsorptive performance can be attributed to the tremendous changes in texture, structure, and surface morphology of adsorbent. The adsorption kinetic analysis shows that the adsorption follows the pseudo-second order kinetics. The apparent activation energy for adsorption is calculated by Arrhenius formula to be 37.6 k J·mol-1, indicating that the adsorption is controlled by both of the diffusion and interfacial adsorption steps. The adsorption data are analyzed using Langmuir and Freundlich isotherms and the results indicate that the Langmuir model provides better correlation of the experimental data. The results conclusively show that the adsorption of MB is a spontaneous behavior and endothermic reaction with the ΔH value of 17.60 k J·mol-1.

3D urchin like V-doped CoP in situ grown on nickel foam as bifunctional electrocatalyst for efficient overall water-splitting

Cobalt phosphide (CoP) is considered to be a potential candidate in the field of electrocatalysis due to its low-cost, abundant resources and high electrochemical stability. However, there is a great space for further improvement of its electrocatalytic performance since its charge transfer rate and catalytic activity have not reached a satisfactory level. Herein, we design and fabricate a three dimensional urchins like V-doped CoP with different amounts of V-doping on nickel foam electrode. The V-doped CoP/NF electrode with optimized amounts of V-doping (10%) exhibits outstanding hydrogen evolution reaction (HER) performance under universal-pH conditions and preeminent oxygen evolution reaction (OER) performance in alkaline media. Notably, the assembled water-splitting cell displays a cell voltage of only 1.53 V at 10 mA·cm−2 and has excellent durability, much better than many reported related bifunctional catalysts. The experiment results and theoretical analysis revealed that vanadium atoms replace cobalt atoms in CoP lattice. Vanadium doping can not only raise the density of electronic states near the Fermi level enhancing the conductivity of the catalyst, but can also optimize the free energy of hydrogen and oxygen-containing intermediates adsorption over CoP, thus promoting its catalytic activity. Moreover, the unique nanostructure of the catalyst provides the various shortened channels for charge transfer and reactant/electrolyte diffusion, which accelerates the electrocatalytic process. Also, the in situ growth strategy can improve the conductivity and stability of the catalyst.

Humidity Sensing Properties of the Sensor Based on V-doped Nanoporous Ti0.9Sn0.1O2 Thin Film

Vanadium doped nanoporous Ti0.9Sn0.1O2 thin film has been prepared on an alumina substrate by sol-gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V-doped nanoporous Ti0.9Sn0.1O2 thin film shows good humidity sensing properties, and impendence of it de- creases more than four orders of magnitude in the relative humidity （RH） range of 11%--95% at 25 ℃. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is sug- gested to explain the humidity sensitive properties.

Vapor growth of V‑doped MoS_(2)monolayers with enhanced B‑exciton emission and broad spectral response

Dynamically engineering the optical and electrical properties in two-dimensional(2D)materials is of great signifcance for designing the related functions and applications.The introduction of foreign-atoms has previously been proven to be a feasible way to tune the band structure and related properties of 3D materials;however,this approach still remains to be explored in 2D materials.Here,we systematically demonstrate the growth of vanadium-doped molybdenum disulfde(V-doped MoS_(2))monolayers via an alkali metal-assisted chemical vapor deposition method.Scanning transmission electron microscopy demonstrated that V atoms substituted the Mo atoms and became uniformly distributed in the MoS_(2)monolayers.This was also confrmed by Raman and X-ray photoelectron spectroscopy.Power-dependent photoluminescence spectra clearly revealed the enhanced B-exciton emission characteristics in the V-doped MoS_(2)monolayers(with low doping concentration).Most importantly,through temperature-dependent study,we observed efcient valley scattering of the B-exciton,greatly enhancing its emission intensity.Carrier transport experiments indicated that typical p-type conduction gradually arisen and was enhanced with increasing V composition in the V-doped MoS_(2),where a clear n-type behavior transited frst to ambipolar and then to lightly p-type charge carrier transport.In addition,visible to infrared wide-band photodetectors based on V-doped MoS_(2)monolayers(with low doping concentration)were demonstrated.The V-doped MoS_(2)monolayers with distinct B-exciton emission,enhanced p-type conduction and broad spectral response can provide new platforms for probing new physics and ofer novel materials for optoelectronic applications.