查看更多>>摘要：Bandgap tuning using rare earth metals as dopants in ferrite-based photocatalytic materials has received a lot of interest because the Fermi 4f energy of these metals generates a sub-energy state in the bandgap generated by the overlapping of Fe-3d and O-2p orbitals.Herein,dysprosium-doped cobalt-nickel mixed ferrite(D-CNFO)and its graphene-reinforced composite(D-CNFO@G)were prepared and an ideal pho-tocatalyst material for azo dye mineralization was proposed.A cost-effective combination of wet-chemical and ultrasonication methods was used to prepare the doped and composite samples.Advanced characterization methodologies were used to scrutinize the optical,compositional,structural,morphological,and photocatalytic characteristics of as-prepared materials.The X-ray diffraction analysis identified the spinel phase's(cubic)structure,while the electronic spectroscopy examination confirmed the prepared samples'rod-like morphology.The UV/visible absorbance spectrum shows the higher light harvesting behavior of the D-CNFO@G in the visible region.The mineralization performance of the D-CNFO and D-CNFO@G composites was analyzed using Congo-red(an anionic dye),a well-known azo dye.The D-CNFO@G sample removes Congo-red dye at a rate almost 2.4％faster than the D-CNFO sample.The experiment involving trapping free radicals indicates that hydroxyl radical plays a crucial role in dye degradation.Since the D-CNFO@G catalyst is magnetic and can be isolated easily from the photocatalytic system,it shows an awkward cycle activity of more than 96％after five mineralization tests.The as-prepared D-CNFO@G composite is proved as an excellent option for azo dye mineralization because of the combined impacts of rare earth doping,graphene reinforcement and nanotechnology.
查看更多>>摘要：The development of full-spectrum photocatalysts active in the near-infrared(NIR)region has gained increasing attention for deleterious pollutant removal.The integration of plasmonic metals with semi-conductors is an effective way to widen the light response range of photocatalysts due to the strong light absorption and fast plasmonic energy transfer of the localized surface plasmon resonance(LSPR).In this work,the full-spectrum responsive Bi@SrTiO3 was prepared via facile solvothermal chemical reduction.The optimal Bi@SrTiO3 achieves exceptional photocatalytic Cr(Ⅵ)reduction efficiency and tetracycline degradation,realizing bi-directional promotion effects on redox reaction.According to density functional theory(DFT)simulations,the extraordinary photocatalytic performance is attributed to the tunable built-in electric field(IEF)of the Ohmic contact.The favorable adaptability in real water and high stability of BSTO-25 were proved by experimental results.And the possible photocatalytic mechanism was proposed based on theoretical calculation and experimental results.Furthermore,the non-toxicity of the BSTO-25 was evaluated by E.coli cultivation,which further proves the feasibility of treating wastewater with BSTO-25.This work provides a new perspective on constructing full-spectrum-driven photocatalysts for applications dealing with environmental remediation.
查看更多>>摘要：Superlattice hydrogen storage alloys offer a compelling advantage with rapid hydriding rate and high storage capacity.However,its practical applications face challenges including complex structure,low dehydriding capacity,and cyclic instability.In this work,we successfully prepared La0.66Mg0.34Ni3.5-xCox superlattice hydrogen storage alloys with enhanced dehydriding capacity and stability by partially substituting Co for Ni.X-ray diffraction(XRD)refinements analysis reveals the presence of(La,Mg)3Ni9,(La,Mg)5Ni19,and LaNi5 phases within the alloy.Following Co substitution in the La0.66Mg0.34Ni3.4Co0.1 alloy,there is a significant increase in content of the(La,Mg)3Ni9 phase and a reduction in the hysteresis factor,resulting in an improved reversible hydrogen storage capacity from 1.45 wt％to 1.60 wt％.The dehydriding kinetics of the alloy is controlled by diffusion model with an activation energy of 8.40 kJ/mol.Furthermore,the dehydriding enthalpy value of the Co-substituted alloy decreases from 30.84 to 29.85 kJ/mol.Impressively,the cycling performance of the alloy after Co substitution exhibits excellent stability,with a capacity retention rate of 92.3％after 100 cycles.These findings provide valuable insights for the development of cost-effective hydrogen storage materials.
查看更多>>摘要：The toxicity of lead ions has become the severe challenge for the all-inorganic lead halide perovskite materials,although some works have reported the lead-free perovskite nanocrystals(NCs),the photo-luminescence quantum yield(PLQY)of these materials is still unsatisfactory.Meanwhile,because the halogen ions can be easily exchanged,the controllable multicolor emission in perovskite NCs is difficult to realize in current reports.In this work,we introduced lanthanide ions into lead-free Cs3Sb2Cl9 perovskite NCs.Benefitting from the energy transfer between Cs3Sb2Cl9 perovskite NC host and lanthanide ions,the multicolor emission was realized.Based on controlling the doping concentration of Tb3+and Eu3+ions,the white light emission under UV excitation would be turned easily in the Tb3+/Eu3+codoped NCs.In addition,efficient energy transfer from perovskite NCs to Tb3+or Eu3+ions is beneficial to improving the optical properties of lead-free perovskite NCs,resulting in maximum PLQYs of red,green and white light emission of 22.6％,19.7％and 28.5％,respectively.Finally,a white light emitting device(WLED)was fabricated with a power efficiency of 18.5 lm/W,which presents the Commission Internationale de l'Eclairage(CIE)of(0.33,0.35).
查看更多>>摘要：Heavily doped upconversion nanoparticles(UCNPs)potentially have exceptional photon upconversion abilities that are promising for diverse applications,such as lasing and super-resolution microscopy.However,heavily doped UCNPs typically can only offer mediocre upconversion luminescence intensity,and there still lacks general guidelines for the design and synthesis of heavily doped UCNPs.Herein,in order to boost the upconversion luminescence of heavily doped UCNPs,we studied the influence of characteristics of the core-shell structure on heavily doped UCNPs'upconversion luminescence.We find that some empirical guidelines derived from conventional UCNPs are not suitable for heavily doped UCNPs.Using NaYbF4:Tm@NaYF4 core-shell UCNPs with a high concentration of Yb3+as a representa-tive,our studies reveal that a rather thick inert NaYF4 shell is needed to protect the UCNPs from surface quenching,and the upconversion luminescence may undergo the cooperative sensitization process,which should be due to the highly concentrated Yb3+dopant.In addition,the upconversion lumines-cence of heavily doped NaYbF4:Tm UCNPs exhibits no obvious dependence on the type of inert shell.Furthermore,our results show that confining both Yb3+and Tm3+dopants in a thin layer(known as theδ-doping strategy)does not work well in the heavily doped UCNPs.Accordingly,we propose a NaYbF4:Tm@NaYbF4@NaYF4 core-shell-shell structure to enhance the luminescence of heavily doped UCNPs,by weakening the dissipation of excitation energy and strengthening the absorption.These findings should be helpful to establish general design principles for developing the brightest possible UCNPs that can meet the requirements of various applications.
查看更多>>摘要：X-ray-activated luminescence materials have broad application prospects in photodynamic therapy of deep tissue.Among them,X-ray-activated persistent luminescence materials(PLMs)exhibiting multiple emission peaks have drawn extensive attention for their capacity to achieve a combination of bioimaging and therapeutic functions.Here,we developed a novel PLM,LiYGeO4∶Bi3+,Pr3+,that simultaneously exhibits UV and NIR dual persistent luminescence(PersL)emissions after irradiation by X-ray.The material can be repeatedly excited by X-ray and emits similar luminescence intensity every time,which shows good PersL stability.In addition,LiYGeO4:Bi3+,Pr3+exhibits photostimulated PersL properties by stimulation with a red light-emitting diode(LED)or NIR laser after long-term decay.This work provides a new choice of X-ray-excited PLMs with UV and NIR dual emission and the novel phosphor shows promise as a potential candidate for the integration of treatment and diagnosis of deep tumors.
查看更多>>摘要：Defective bulk catalysts based on TiO2 have superior catalytic performance for propane dehydrogenation(PDH).The oxygen vacancy concentration and the number of active sites on the catalyst surface can be effectively tuned by doping metal in TiO2.Herein,yttrium(Y)-doped titanium dioxide(nY/TiOx)catalysts were in-situ synthesized via the coprecipitation method to study the effect of rare earth metal Y doping on the structure of TiO2 and the catalytic performance for PDH.Experimental results demonstrate that Y-doped TiO2 exhibits higher catalytic activity,propylene selectivity and stability than bare TiO2.Full characterizations with X-ray diffraction(XRD),high-resolution transmission electron microscope(HRTEM),X-ray photoelectron spectroscopy(XPS),infrared spectroscopy of pyridine adsorption(Py-IR),temperature-programmed desorption of ammonia(NH3-TPD),H2 temperature-programmed reduction(H2-TPR),and Raman techniques on these catalysts reveal that Y3+can enter TiO2 lattice,and the lattice stability of the catalyst can be enhanced by replacing Ti4+to form Y-O-Ti structure.Meanwhile,the introduction of an appropriate amount of Y can obviously promote the PDH reaction by adjusting the acidity of the catalyst,improving the release capacity of TiO2 lattice oxygen and increasing the formation of active centers.Nevertheless,excessive Y doping will lead to pore clogging,and the exposure of active sites will be reduced,resulting in the degradation of catalytic performance.
查看更多>>摘要：The Mn-Ce-Fe mixed oxide(MCFe)was prepared by co-precipitation and the catalytic performance was tested by using 1,2-dichlorobenzene(1,2-DCB)and furan as model molecules of PCDD/F.The effect of O2 concentration,SO2 and NO on the catalytic activity was studied.At 270 ℃,the MCFe oxide catalyst presents significant simultaneous removal efficiency of 75.25％and 100％for 1,2-DCB and furan,respectively.Brunauer-Emmett-Teller(BET)method(BET),X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FT-IR),H2-temperature programmed reduction(H2-TPR),NH3-temperature programmed desorption(NH3-TPD)and O2-TPD were used to characterize the catalysts before and after the reaction.Competition tests suggest that the oxidation behavior of furan occurred prior to that of 1,2-DCB.According to the inter-mediate products detected by gas chromatography-mass spectrometry(GC-MS),the by-products include chlorinated hydrocarbons,long-chain hydrocarbons,ketone,etc.Possible catalytic oxidation reaction paths are proposed.
查看更多>>摘要：A novel Nd-Fe-B type permanent magnet with excellent thermal stability was designed by Co replacing Fe in the main phase and the grain boundary phase.The remanence and coercivity temperature coef-ficient reach 0.058％/℃ and 0.465％/℃ in the temperature range from 25 to 100 ℃,which are much lower than those of commercial Nd-Fe-B magnet.An enhanced Curie temperature is obtained for the novel magnet due to the Co substitution,which significantly improves the operating temperature.The microstructure result reveals that an amorphous phase exists in the intergranular grains which is probably responsible for the deterioration of intrinsic coercivity.This work can provide a reference for the design and optimization of components of sintered Nd-Fe-B magnets with excellent thermal stability.
查看更多>>摘要：By anchoring Tb3+ions on its free carboxyl groups of the nanocaged NiMOF,a dual-emission self-cali-brating sensor of Tb3+@NiMOF was fabricated through coordination post-synthetic modification(PSM)strategy.With Tb3+ions as the secondary fluorescent signal and sensing active sites,Tb3+@NiMOF presents great potentials in visually and efficiently monitoring EPI in serum,with high sensitivity and selectivity,fast response,excellent recyclable,and the low detection limit(LOD,3.06 ng/mL).Further-more,a tandem combinational logic gate based intelligent detection system was constructed to improve the practicability and convenience of epinephrine(EPI)detection in serum by comparing the light emitted colour with the series standard colour cards preset in the smartphone.This work provides a promising approach of developing metal-organic frameworks(MOFs)based self-calibrating sensors for intelligent detection of bioactive molecules.
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