A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of the...A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of these systems by maximizing their light absorption,engineering more stable redox couples,and discovering new O2 and H2 evolutions co-catalysts.In this work,Au decorated WO3/g-C3N4 Z-scheme nanocomposites are fabricated via wet-chemical and photo-deposition methods.The nanocomposites are utilized in photocatalysis for H2 production and 2,4-dichlorophenol(2,4-DCP)degradation.It is investigated that the optimized 4Au/6%WO3/CN nanocomposite is highly efficient for production of 69.9 and 307.3μmol h−1 g−1 H2 gas,respectively,under visible-light(λ>420 nm)and UV–visible illumination.Further,the fabricated 4Au/6%WO3/CN nanocomposite is significant(i.e.,100%degradation in 2 h)for 2,4-DCP degradation under visible light and highly stable in photocatalysis.A significant 4.17%quantum efficiency is recorded for H2 production at wavelength 420 nm.This enhanced performance is attributed to the improved charge separation and the surface plasmon resonance effect of Au nanoparticles.Solid-state density functional theory simulations are performed to countercheck and validate our experimental data.Positive surface formation energy,high charge transfer,and strong non-bonding interaction via electrostatic forces confirm the stability of 4Au/6%WO3/CN interface.展开更多
X-ray detection is crucial across various sectors,but traditional techniques face challenges such as inefficient data transmission,redundant sensing,high power consumption,and complexity.The innovative idea of a retin...X-ray detection is crucial across various sectors,but traditional techniques face challenges such as inefficient data transmission,redundant sensing,high power consumption,and complexity.The innovative idea of a retinomorphic X-ray detector shows great potential.However,its implementation has been hindered by the absence of active layers capable of both detecting X-rays and serving as memory storage.In response to this critical gap,our study integrates hybrid perovskite with hydrion-conductive organic cations to develop a groundbreaking retinomorphic X-ray detector.This novel device stands at the nexus of technological innovation,utilizing X-ray detection,memory,and preprocessing capabilities within a single hardware platform.The core mechanism underlying this innovation lies in the transport of electrons and holes within the metal halide octahedral frameworks,enabling precise X-ray detection.Concurrently,the hydrion movement through organic cations endows the device with short-term resistive memory,facilitating rapid data processing and retrieval.Notably,our retinomorphic X-ray detector boasts an array of formidable features,including reconfigurable shortterm memory,a linear response curve,and an extended retention time.In practical terms,this translates into the efficient capture of motion projections with minimal redundant data,achieving a compression ratio of 18.06%and an impressive recognition accuracy of up to 98.6%.In essence,our prototype represents a paradigm shift in X-ray detection technology.With its transformative capabilities,this retinomorphic hardware is poised to revolutionize the existing X-ray detection landscape.展开更多
Over the past decade, ultrathin lanthanide oxides （Ln2O3, Ln = La to Lu） nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many u...Over the past decade, ultrathin lanthanide oxides （Ln2O3, Ln = La to Lu） nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many unprecedented properties （big surface area, high surface effect, physical and chemical activities） and is thus being explored for numerous promising applications. In this review, a brief introduction of ultrathin Ln2O3 nanomaterials was given and their unique advantages were highlighted. Then, the typical synthetic methodologies were summarized and compared （thermal decomposition, solvothermal, soft template, co-precipition and microwave etc.）. Due to the high surface effect, some promising applications of ultmthin Ln203 nanomaterials, such as drug delivery and catalysis of CO oxidation, were reviewed. Finally, on the basis of current achievements on ultrathin Ln203 nanomaterials, personal perspectives and challenges on future research directions were proposed.展开更多
The thin film of heat-sensitive materials has been widely concerned with the current trend of miniaturization and integration of sensors.In this work,Mn1.56 Co0.96 Ni0.48 O4(MCNO)thin films were prepared on Si O2/Si s...The thin film of heat-sensitive materials has been widely concerned with the current trend of miniaturization and integration of sensors.In this work,Mn1.56 Co0.96 Ni0.48 O4(MCNO)thin films were prepared on Si O2/Si substrates by sputtering with Mn–Co–Ni alloy target and then annealing in air at different temperatures(650–900℃).The X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM)analysis indicated that the main crystalline phase of MCNO thin films was spinel crystal structure;the surface of the thin films was very dense and uniform.The electrical properties of the thin films were studied in the temperature range of–5–50℃.The MCNO thin film with a low room temperature resistance R25 of 71.1 kΩand a high thermosensitive constant B value of 3305 K was obtained at 750℃.X-ray photoelectron spectroscopy(XPS)analysis showed that the concentration of Mn3+and Mn4+cations in MCNO thin films is the highest when annealing temperature is 750℃.The complex impedance analysis revealed internal conduction mechanism of the MCNO thin film and the resistance of the thin film was dominated by grain boundary resistance.展开更多
The high cost and poor durability of Pt nanoparticles(NPs)have always been great challenges to the commercialization of proton exchange membrane fuel cells(PEMFCs).Pt-based intermetallic NPs with a highly ordered stru...The high cost and poor durability of Pt nanoparticles(NPs)have always been great challenges to the commercialization of proton exchange membrane fuel cells(PEMFCs).Pt-based intermetallic NPs with a highly ordered structure are considered as promising catalysts for PEMFCs due to their high catalytic activity and stability.Here,we reported a facile method to synthesize N-doped carbon encapsulated PtZn intermetallic(PtZn@NC)NPs via the pyrolysis of Pt@Zn-based zeolitic imidazolate framework-8(Pt@ZIF-8)composites.The catalyst obtained at 800℃(10%-PtZn@NC-800)was found to exhibit a half-wave potential(Ev2)up to 0.912 V versus reversible hydrogen electrode(RHE)for the cathodic oxygen reduction reaction in an acidic medium,which shifted by 26 mV positively compared to the benchmark Pt/C catalyst.Besides,the mass activity and specific activity of 10%-PtZn@NC-800 at 0.9 V versus RHE were nearly 3 and 5 times as great as that of commercial Pt/C,respectively.It is worth noting that the PtZn@NC showed excel Ient stability in oxygen reducti on reacti on(ORR)with just 1 mV of the Ev2 loss after 5,000 cycles,which is superior to that of most reported PtM catalysts(especially those disordered solid solutions).Furthermore,such N-doped carb on shell encapsulated PtZn intermetallic NPs showed significa ntly enha need performances towards the anodic oxidation reaction of organic small molecules(such as methanol and formic acid).The synergistic effects of the N doped carbon encapsulation structure and intermetallic NPs are responsible for outstanding performances of the catalysts.This work provides us a new engineering strategy to acquire highly active and stable multifunctional catalysts for PEMFCs.展开更多
Sensitive and fast detection of neutrons and gamma rays is vital for homeland security,high-energy physics,and proton therapy.Fast-neutron detectors rely on light organic scintillators,andγ-ray detectors use heavy in...Sensitive and fast detection of neutrons and gamma rays is vital for homeland security,high-energy physics,and proton therapy.Fast-neutron detectors rely on light organic scintillators,andγ-ray detectors use heavy inorganic scintillators and semiconductors.Efficient mixed-field detection using a single material is highly challenging due to their contradictory requirements.Here we report hybrid perovskites(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed-field radiation detection.High neutron absorption due to a high density of hydrogen,strong radiative recombination within the highly confined[PbX_(6)]^(4-)layer,and sub-nanometer distance between absorption sites and radiative centers,enable a light yield of 41000 photons/MeV,detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons andγ-rays,outperforming commonly used fast-neutron scintillators.Neutron energy spectrum,time-of-flight based fast-neutron/γ-ray discrimination and neutron yield monitoring were all successfully achieved using(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)detectors.We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction.We envision that molecular hybridized scintillators open a new avenue for mixed-field radiation detection and imaging.展开更多
Herein,we prepared a bimetallic layered double hydroxide(FeCo LDH)featuring a dandelion-like structure.Anchoring of CeO_(2)onto FeCo LDH produced interfaces between the functionalizing CeO_(2)and the parent LDH.Compar...Herein,we prepared a bimetallic layered double hydroxide(FeCo LDH)featuring a dandelion-like structure.Anchoring of CeO_(2)onto FeCo LDH produced interfaces between the functionalizing CeO_(2)and the parent LDH.Comparative electrochemical studies were carried out.Onset potential,overpotential,and Tafel slope point to the superior oxygen-evolving performance of CeO_(2)-FeCo LDH with respect to FeCo LDH,therefore,demonstrating the merits of CeO_(2)functionalization.The electronic structures of Fe,Co,and Ce were analyzed by X-ray photoelectron spectroscopy(XPS)and electron energy loss spectroscopy(EELS)from which the increase of Co^(3+)and the concurrent lowering of Ce^(4+)were established.With the use of CeO_(2)-FeCo LDH,accelerated formation at a sizably reduced potential of Co-OOH,one of the key intermediates preceding the release of O_(2)was observed by in situ Raman spectroscopy.We now have the atomic-level and location-specific evidence,the increase of the active Co^(3+)across the interface to correlate the enhanced catalytic performance with CeO_(2)functionalization.展开更多
Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to...Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to facilitate the formation of oxygencontaining intermediates.However,the difficulties encountered in the conversion of intermediates(M–OH,M–O,and M–OOH)lead to low efficiency.Decorations of transition metal catalysts with foreign elements are regarded effective solutions,among which decoration with Ce-based materials(CeBM)is the most prominent.This review investigates the current status and future prospects of CeBM-decorated transition metal electrocatalysts.By presenting a thorough account of the latest development,we aim to set a common ground for the research community for a deeper understanding of the roles of CeBM that originate from its unique electronic structure and abundant oxygen vacancies.Moreover,we wish to provide our own perspectives as to how to further the design of Ce-based OER electrocatalysts and where such catalysts may be applied in fields beyond electrocatalysis.展开更多
Aldehyde groups were intentionally equipped on the cyanide-bridged[Fe_(2)Co_(2)]square molecules:{[(Tp*)Fe(CN)_(3)Co(bpy^(CHO))_(2)]_(2)-[PF_(6)]_(2)}·4MeOH(1,Tp*=hydrotris(3,5-dimethylpyrazol-1-yl)borate;bpy^(CH...Aldehyde groups were intentionally equipped on the cyanide-bridged[Fe_(2)Co_(2)]square molecules:{[(Tp*)Fe(CN)_(3)Co(bpy^(CHO))_(2)]_(2)-[PF_(6)]_(2)}·4MeOH(1,Tp*=hydrotris(3,5-dimethylpyrazol-1-yl)borate;bpy^(CHO)=4-formyl-4′-methyl-2,2′-bipyridine),thus providing chemical-active windows for post-modification towards desired functions.In this contribution,by taking advantage of efficient Schiff-base condensation between the aldehyde-substituted bipyridine derivative(bpyCHO)and alkyl diamines(H_(2)N-(CH_(2))_(n)NH_(2)),two discrete[Fe_(2)Co_(2)]compounds{[(Tp∗)Fe(CN)_(3)Co(bpy^(C=N(CH_(2))_(n)N=C)bpy)]2[PF_(6)]_(2)}⋅6DMF(2,n=5;3,n=7)were prepared,where the cyanide-bridged[Fe_(2)Co_(2)]square cores were encapsulated by the flexible alkyl chains.Variable-temperature single-crystal X-ray diffraction and magnetic studies revealed complete thermo(T_(1/2)=233 K(2)and 237 K(3))and photo-induced electron transfer event accompanying spin transition between the diamagnetic[Fe^(Ⅱ)_(LS2)Co^(Ⅲ)_(LS2)]state and the paramagnetic[Fe^(Ⅲ)_(LS2)Co^(Ⅱ)_(HS2)]state(LS,low spin;HS,high spin).In addition,the bidirectional switching between the two states was achieved with alternating laser irradiation at 808 and 532 nm at 10 K.展开更多
In this work,we screened three Grubbs catalysts and two Hoveyda-Grubbs catalysts for the production of H_(2) by dehydrogenation of formic acid(FA).The best results were achieved with the use of a first-generation Hove...In this work,we screened three Grubbs catalysts and two Hoveyda-Grubbs catalysts for the production of H_(2) by dehydrogenation of formic acid(FA).The best results were achieved with the use of a first-generation Hoveyda-Grubbs catalyst.With a catalyst loading of mere 0.5μmol, a maximum TON of 36356 was obtained within 3 h.Two key intermediates were identified by using 1H NMR and high-resolution electrospray ionization mass spectroscopy(HRESI-MS),based on which a mechanism possibly responsible for the observed catalysis was proposed.展开更多
Metal halide perovskites(MHPs)have demonstrated excellent performances in detection of X-rays and gamma-rays.Most studies focus on improving the sensitivity of single-pixel MHP detectors.However,little work pays atten...Metal halide perovskites(MHPs)have demonstrated excellent performances in detection of X-rays and gamma-rays.Most studies focus on improving the sensitivity of single-pixel MHP detectors.However,little work pays attention to the dark current,which is crucial for the back-end circuit integration.Herein,the requirement of dark current is quantitatively evaluated as low as 10^(−9)A/cm^(2)for X-ray imagers integrated on pixel circuits.Moreover,through the semiconductor device analysis and simulation,we reveal that the main current compositions of thick perovskite X-ray detectors are the thermionic-emission current(J_(T))and the generation-recombination current(J_(g-r)).The typical observed failures of p-n junctions in thick detectors are caused by the high generation-recombination current due to the band mismatch and interface defects.This work provides a deep insight into the design of high sensitivity and low dark current perovskite X-ray detectors.展开更多
Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs)of the general formula{[Ln(HIDA)_(2)H_(2)O]ClO_(4)·H_(2)O}_n(Ln=La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_(2)IDA=iminodiacetic acid)and[Ln(TT)(H...Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs)of the general formula{[Ln(HIDA)_(2)H_(2)O]ClO_(4)·H_(2)O}_n(Ln=La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_(2)IDA=iminodiacetic acid)and[Ln(TT)(HTT)(H_(2)O)_3]_n(Ln=Eu(7),Gd(8),Tb(9),Dy(10),and Eu:Tb(11);H_(2)TT=tartaric acid)were synthesized by reacting Ln(ClO_(4))_3 with iminodiacetic acid and L-tartaric acid,respectively.All compounds were structurally characterized by single-crystal X-ray diffraction.Elemental analyses are co nsistent with the corre sponding crystallographically generated formulas.Mo reover,the luminescence properties of both the single and mixed-lanthanide complexes were studied.Near infrared,red,and green emissions that are characteristic of Nd(Ⅲ),Eu(Ⅲ),and Tb(Ⅲ)are observed for 2,3/7,and 5/9,respectively.For the two mixed-lanthanide complex systems 6 and 11,depending on the relative amount of Eu(Ⅲ)and Tb(Ⅲ),the color of emission can be fine-tuned.It is found that a small amount of Eu(Ⅲ)is adequate for the observation of the most intense transition of Eu(Ⅲ).This is believed to be a result of energy transfer from Tb(Ⅲ)to Eu(Ⅲ)within the same complex-a conclusion supported by the significantly shortened lifetime of Tb(Ⅲ)and the accompanying enhanced lifetime of Eu(Ⅲ)in the mixedlanthanide complex with respect to the corresponding values for the pure Tb(Ⅲ)and Eu(Ⅲ)complexes with the same ligand.展开更多
The slow oxygen reduction process at the cathode and the scarcity of platinum-based metals lead to limited applications in fuel cells and metal-air cells.Recently,transition metal and nitrogen co-doped carbon-based ca...The slow oxygen reduction process at the cathode and the scarcity of platinum-based metals lead to limited applications in fuel cells and metal-air cells.Recently,transition metal and nitrogen co-doped carbon-based catalysts(M–N–C)are regarded as the most prospective non-precious metal catalysts for future fuel cell applications.It is verified theoretically and experimentally that the metal and nitrogen coordination structure is the main catalytic activity center of oxygen reduction reaction(ORR),so constructing M–N–C materials with high available surface area and structural stability is an effective way to accelerate ORR.Herein,we deliberately synthesize a one-dimensional ZIF structure to fabricate one-dimensional porous Fe–N–C nanostick via two-step pyrolysis.Excitingly,the as-synthesized exhibited an outstanding ORR activity in alkaline medium(E_(1/2)of 0.928 V),as well as superior stability(only changed 7 mV after 10,000 cycles in alkaline medium).Our results show that the reduction of electrocatalyst dimensionality can promote mass transport and increase the accessibility of active sites,thus optimizing their performance in ORR.This work is a good demonstration of the importance of a rational design of catalyst structure for efficient ORR.展开更多
Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and signif...Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.展开更多
Postsynthesis of the paramagnetic square-shaped complex{[(Tp*Me)Fe(μ-CN)_(2)(CN)][Co(dmbpy)_(2)]}_(2)(BPh_(4))_(2)·6MeCN·H2O[1,Tp*Me=tris(3,4,5-trimethylpyrazole)-borate;dmbpy=4,4′-dimethyl-2,2′-bipyridin...Postsynthesis of the paramagnetic square-shaped complex{[(Tp*Me)Fe(μ-CN)_(2)(CN)][Co(dmbpy)_(2)]}_(2)(BPh_(4))_(2)·6MeCN·H2O[1,Tp*Me=tris(3,4,5-trimethylpyrazole)-borate;dmbpy=4,4′-dimethyl-2,2′-bipyridine)]by grafting transition metal(II)thiocyanates via its terminal cyano groups afforded three hexanuclear[Fe_(2)Co_(2)M_(2)]clusters(M=Zn,2;Co,3;Cd,4).The peripheral metal-complex units serving as excellent electron acceptors were found to help stabilize the low-temperature state of Fe^(II,LS)–Co^(III,LS) within the complex core.展开更多
Hybrids composed of biocompatible polymers reinforced with inorganic nanomaterials are useful for many biomedical applications including implantation and tissue regeneration and engineering.In this work,we report a ne...Hybrids composed of biocompatible polymers reinforced with inorganic nanomaterials are useful for many biomedical applications including implantation and tissue regeneration and engineering.In this work,we report a new type of hybrid prepared by doping ultrathin nanowires of lanthanide hydroxycarbonates into classical biocompatible poly(citrates-siloxane).The doping of the inorganic nanowires imparts the hybrids with excellent miscibility with the polymeric matrix,producing hybrids with high elasticity and high tensile strength.The hybrids containing Eu(III)and Gd(III)display their respective luminescence and magnetic properties and thus,offer opportunities to monitor the fate of such hybrids when used in vivo.Insignificant degradation and excellent biocompatibility of these hybrids have also been demonstrated.Together,these favorable traits portend useful applications of the newly developed hybrid elastomers.展开更多
Many sandwich-type lanthanide complexes show extremely high energy barriers(Ueff)for the reversal of magnetization and high blocking temperatures,being the star molecules in the research area of single-molecule magnet...Many sandwich-type lanthanide complexes show extremely high energy barriers(Ueff)for the reversal of magnetization and high blocking temperatures,being the star molecules in the research area of single-molecule magnets.Herein,the preparation,structural determination,and magnetic property studies of two ansa-bridged Er-COT(COT=cyclooctatetraenyl dianion)complexes[KDME_(2)][Er((η^(8)-COT-Si^(Me2))_(2)O)](1)and[KDME_(2)][Er((η^(8)-COT-Si^(iPr2))_(2)O)]K[Er((η^(8)-COT-Si^(iPr2))_(2)O)](2)were reported.The Er(Ⅲ)ions in both complexes are sandwiched by two COT rings which are ansa-bridged by a[Si-O-Si]group.Magnetic studies reveal both complexes display slow magnetic relaxations with comparable energy barriers(228(5)K for 1,and 196(4)K for 2)and blocking temperatures(10.5 K for both complexes).The difference in the relaxation times(τ)for the two complexes was studied in details:different molecular vibrations induced by the substituents are the main reason forτfor 1 being about 10 times longer than for 2 at the same temperature above 10 K,while the quantum tunnelling of magnetization relaxation time(τQTM)for 2 is about 10 times longer than for 1 below 8 K,probably owing to the different dipolar interactions.Further rearrangement of molecular network with such ansa-bridged SMMs is promising to design molecular magnetic materials with enhanced properties or new properties.展开更多
Direct X-ray detectors based on semiconductors have drawn great attention from researchers in the pursuing of higher imaging quality.However,many previous works focused on the optimization of detection performances bu...Direct X-ray detectors based on semiconductors have drawn great attention from researchers in the pursuing of higher imaging quality.However,many previous works focused on the optimization of detection performances but seldomly watch them in an overall view and analyze how they will influence the detective quantum efficiency(DQE)value.Here,we propose a numerical model which shows the quantitative relationship between DQE and the properties of X-ray detectors and electric circuits.Our results point out that pursuing high sensitivity only is meaningless.To reduce the medical X-ray dose by 80%,the requirement for X-ray sensitivity is only at a magnitude of 103µCGy-1·cm^(-2).To achieve the DQE=0.7 at X-ray sensitivity air from 1248 to 8171µCGy-1air·cm^(-2),the requirements on dark current density ranges from 10 to 100 nA·cm^(-2) and the fluctuation of current density should fall in 0.21 to 1.37 nA·cm^(-2).展开更多
基金the National Natural Science Foundation of China (Nos. 11874169, 11574106, 61771448, and 51635007)the Double first-class research funding of China-EU Institute for Clean and Renewable Energy (ICARE-RP-2018-SOLAR-003)+1 种基金the Engineering and Physical Science Research Council, UK (EPSRC grant No EP/ P510956/1 and EP/R512801/1the China Postdoctoral Science Foundation under Grant No. 2017M622404
文摘A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of these systems by maximizing their light absorption,engineering more stable redox couples,and discovering new O2 and H2 evolutions co-catalysts.In this work,Au decorated WO3/g-C3N4 Z-scheme nanocomposites are fabricated via wet-chemical and photo-deposition methods.The nanocomposites are utilized in photocatalysis for H2 production and 2,4-dichlorophenol(2,4-DCP)degradation.It is investigated that the optimized 4Au/6%WO3/CN nanocomposite is highly efficient for production of 69.9 and 307.3μmol h−1 g−1 H2 gas,respectively,under visible-light(λ>420 nm)and UV–visible illumination.Further,the fabricated 4Au/6%WO3/CN nanocomposite is significant(i.e.,100%degradation in 2 h)for 2,4-DCP degradation under visible light and highly stable in photocatalysis.A significant 4.17%quantum efficiency is recorded for H2 production at wavelength 420 nm.This enhanced performance is attributed to the improved charge separation and the surface plasmon resonance effect of Au nanoparticles.Solid-state density functional theory simulations are performed to countercheck and validate our experimental data.Positive surface formation energy,high charge transfer,and strong non-bonding interaction via electrostatic forces confirm the stability of 4Au/6%WO3/CN interface.
基金supported by the National Natural Science Foundation of China(U23A20359)the Major State Basic Research Development Program of China(2021YFB3201000)+2 种基金the National Natural Science Foundation of China(62134003,623B2033,and 62074066)the Natural Science Foundation of Hubei Province(2021CFA036,2020CFA034)the Shenzhen Science and Technology Program(SGDX20230116093205009).
文摘X-ray detection is crucial across various sectors,but traditional techniques face challenges such as inefficient data transmission,redundant sensing,high power consumption,and complexity.The innovative idea of a retinomorphic X-ray detector shows great potential.However,its implementation has been hindered by the absence of active layers capable of both detecting X-rays and serving as memory storage.In response to this critical gap,our study integrates hybrid perovskite with hydrion-conductive organic cations to develop a groundbreaking retinomorphic X-ray detector.This novel device stands at the nexus of technological innovation,utilizing X-ray detection,memory,and preprocessing capabilities within a single hardware platform.The core mechanism underlying this innovation lies in the transport of electrons and holes within the metal halide octahedral frameworks,enabling precise X-ray detection.Concurrently,the hydrion movement through organic cations endows the device with short-term resistive memory,facilitating rapid data processing and retrieval.Notably,our retinomorphic X-ray detector boasts an array of formidable features,including reconfigurable shortterm memory,a linear response curve,and an extended retention time.In practical terms,this translates into the efficient capture of motion projections with minimal redundant data,achieving a compression ratio of 18.06%and an impressive recognition accuracy of up to 98.6%.In essence,our prototype represents a paradigm shift in X-ray detection technology.With its transformative capabilities,this retinomorphic hardware is poised to revolutionize the existing X-ray detection landscape.
基金supported by the Start-up Funding from Xi’an Jiaotong Universitythe Fundamental Research Funds for the Central Universities (2015qngz12)+1 种基金the National Natural Science Foundation of China (21371140)the China National Funds for Excellent Young Scientists (21522106)
文摘Over the past decade, ultrathin lanthanide oxides （Ln2O3, Ln = La to Lu） nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many unprecedented properties （big surface area, high surface effect, physical and chemical activities） and is thus being explored for numerous promising applications. In this review, a brief introduction of ultrathin Ln2O3 nanomaterials was given and their unique advantages were highlighted. Then, the typical synthetic methodologies were summarized and compared （thermal decomposition, solvothermal, soft template, co-precipition and microwave etc.）. Due to the high surface effect, some promising applications of ultmthin Ln203 nanomaterials, such as drug delivery and catalysis of CO oxidation, were reviewed. Finally, on the basis of current achievements on ultrathin Ln203 nanomaterials, personal perspectives and challenges on future research directions were proposed.
基金supported by National Key R&D Program of China(Grant No.2017YFB0406405)National Natural Science Foundation of China(Grant No.61571203)。
文摘The thin film of heat-sensitive materials has been widely concerned with the current trend of miniaturization and integration of sensors.In this work,Mn1.56 Co0.96 Ni0.48 O4(MCNO)thin films were prepared on Si O2/Si substrates by sputtering with Mn–Co–Ni alloy target and then annealing in air at different temperatures(650–900℃).The X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM)analysis indicated that the main crystalline phase of MCNO thin films was spinel crystal structure;the surface of the thin films was very dense and uniform.The electrical properties of the thin films were studied in the temperature range of–5–50℃.The MCNO thin film with a low room temperature resistance R25 of 71.1 kΩand a high thermosensitive constant B value of 3305 K was obtained at 750℃.X-ray photoelectron spectroscopy(XPS)analysis showed that the concentration of Mn3+and Mn4+cations in MCNO thin films is the highest when annealing temperature is 750℃.The complex impedance analysis revealed internal conduction mechanism of the MCNO thin film and the resistance of the thin film was dominated by grain boundary resistance.
基金This work was supported by the National Key Research and Development Program of China(Nos.2017YFA0206500 and 2017YFA0206801)the National Basic Research Program of China(No.2015CB932301)the National Natural Science Foundation of China(Nos.21671163 and 21721001).
文摘The high cost and poor durability of Pt nanoparticles(NPs)have always been great challenges to the commercialization of proton exchange membrane fuel cells(PEMFCs).Pt-based intermetallic NPs with a highly ordered structure are considered as promising catalysts for PEMFCs due to their high catalytic activity and stability.Here,we reported a facile method to synthesize N-doped carbon encapsulated PtZn intermetallic(PtZn@NC)NPs via the pyrolysis of Pt@Zn-based zeolitic imidazolate framework-8(Pt@ZIF-8)composites.The catalyst obtained at 800℃(10%-PtZn@NC-800)was found to exhibit a half-wave potential(Ev2)up to 0.912 V versus reversible hydrogen electrode(RHE)for the cathodic oxygen reduction reaction in an acidic medium,which shifted by 26 mV positively compared to the benchmark Pt/C catalyst.Besides,the mass activity and specific activity of 10%-PtZn@NC-800 at 0.9 V versus RHE were nearly 3 and 5 times as great as that of commercial Pt/C,respectively.It is worth noting that the PtZn@NC showed excel Ient stability in oxygen reducti on reacti on(ORR)with just 1 mV of the Ev2 loss after 5,000 cycles,which is superior to that of most reported PtM catalysts(especially those disordered solid solutions).Furthermore,such N-doped carb on shell encapsulated PtZn intermetallic NPs showed significa ntly enha need performances towards the anodic oxidation reaction of organic small molecules(such as methanol and formic acid).The synergistic effects of the N doped carbon encapsulation structure and intermetallic NPs are responsible for outstanding performances of the catalysts.This work provides us a new engineering strategy to acquire highly active and stable multifunctional catalysts for PEMFCs.
基金China Postdoctoral Science Foundation,Grant/Award Number:2021T140234Fund for the Natural Science Foundation of Hubei Province,Grant/Award Numbers:2020CFA034,2021CFA036+3 种基金HCP Program for HUSTInnovation Fund of WNLOMajor State Basic Research Development Program of China,Grant/Award Numbers:2018YFA0703200,2021YFB3201000National Natural。
文摘Sensitive and fast detection of neutrons and gamma rays is vital for homeland security,high-energy physics,and proton therapy.Fast-neutron detectors rely on light organic scintillators,andγ-ray detectors use heavy inorganic scintillators and semiconductors.Efficient mixed-field detection using a single material is highly challenging due to their contradictory requirements.Here we report hybrid perovskites(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed-field radiation detection.High neutron absorption due to a high density of hydrogen,strong radiative recombination within the highly confined[PbX_(6)]^(4-)layer,and sub-nanometer distance between absorption sites and radiative centers,enable a light yield of 41000 photons/MeV,detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons andγ-rays,outperforming commonly used fast-neutron scintillators.Neutron energy spectrum,time-of-flight based fast-neutron/γ-ray discrimination and neutron yield monitoring were all successfully achieved using(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)detectors.We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction.We envision that molecular hybridized scintillators open a new avenue for mixed-field radiation detection and imaging.
基金This work was financially supported by Shenzhen Nobel Prize Scientists Laboratory Project(No.C17213101)Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)+6 种基金Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(No.2018B030322001)China Postdoctoral Science Foundation(No.2018M642133,X.Y.Z.)Post-doctorate Scientific Research Fund for staying(coming to)Shenzhen(No.K21217502,X.Y.Z.)the National Natural Science Foundation of China(No.21671096,Z.G.L.)Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials(No.ZDSYS20200421111401738,Z.G.L.)The authors also acknowledge the assistance of Southern University of Science and Technology Core Research Facilities(SUSTech CRF)Key Laboratory of Energy Conversion and Storage Technologies(Southern University of Science and Technology).
文摘Herein,we prepared a bimetallic layered double hydroxide(FeCo LDH)featuring a dandelion-like structure.Anchoring of CeO_(2)onto FeCo LDH produced interfaces between the functionalizing CeO_(2)and the parent LDH.Comparative electrochemical studies were carried out.Onset potential,overpotential,and Tafel slope point to the superior oxygen-evolving performance of CeO_(2)-FeCo LDH with respect to FeCo LDH,therefore,demonstrating the merits of CeO_(2)functionalization.The electronic structures of Fe,Co,and Ce were analyzed by X-ray photoelectron spectroscopy(XPS)and electron energy loss spectroscopy(EELS)from which the increase of Co^(3+)and the concurrent lowering of Ce^(4+)were established.With the use of CeO_(2)-FeCo LDH,accelerated formation at a sizably reduced potential of Co-OOH,one of the key intermediates preceding the release of O_(2)was observed by in situ Raman spectroscopy.We now have the atomic-level and location-specific evidence,the increase of the active Co^(3+)across the interface to correlate the enhanced catalytic performance with CeO_(2)functionalization.
基金This research was made possible as a result of a generous grant from Shenzhen Nobel Prize Scientists Laboratory Project(grant no.C17213101)Guangdong Provincial Key Laboratory of Catalysis(no.2020B121201002)+1 种基金Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(no.2018B030322001)China Postdoctoral Science Foundation(no.2018M642133).
文摘Non-noble metal catalysts are suitable for the oxygen evolution reaction(OER)owing to their original oxidation states and oxygen coordination environments,which can regulate the adsorption of OH−at the active sites to facilitate the formation of oxygencontaining intermediates.However,the difficulties encountered in the conversion of intermediates(M–OH,M–O,and M–OOH)lead to low efficiency.Decorations of transition metal catalysts with foreign elements are regarded effective solutions,among which decoration with Ce-based materials(CeBM)is the most prominent.This review investigates the current status and future prospects of CeBM-decorated transition metal electrocatalysts.By presenting a thorough account of the latest development,we aim to set a common ground for the research community for a deeper understanding of the roles of CeBM that originate from its unique electronic structure and abundant oxygen vacancies.Moreover,we wish to provide our own perspectives as to how to further the design of Ce-based OER electrocatalysts and where such catalysts may be applied in fields beyond electrocatalysis.
基金the National Natural Science Foundation of China (No.11574106, 61771448and 51635007)the China Postdoctoral Science Foundation (No.2017M622404)and the Fundamental Research Projects of Shenzhen City (No.JCYJ20150831202835225).
基金This work was supported by the National Natural Science Foundation of China(21671095,21901108),and start-up fund from SUSTech.We thank Dr.Bin Chen from Soochow University for UV-Vis-NIR measurements.
文摘Aldehyde groups were intentionally equipped on the cyanide-bridged[Fe_(2)Co_(2)]square molecules:{[(Tp*)Fe(CN)_(3)Co(bpy^(CHO))_(2)]_(2)-[PF_(6)]_(2)}·4MeOH(1,Tp*=hydrotris(3,5-dimethylpyrazol-1-yl)borate;bpy^(CHO)=4-formyl-4′-methyl-2,2′-bipyridine),thus providing chemical-active windows for post-modification towards desired functions.In this contribution,by taking advantage of efficient Schiff-base condensation between the aldehyde-substituted bipyridine derivative(bpyCHO)and alkyl diamines(H_(2)N-(CH_(2))_(n)NH_(2)),two discrete[Fe_(2)Co_(2)]compounds{[(Tp∗)Fe(CN)_(3)Co(bpy^(C=N(CH_(2))_(n)N=C)bpy)]2[PF_(6)]_(2)}⋅6DMF(2,n=5;3,n=7)were prepared,where the cyanide-bridged[Fe_(2)Co_(2)]square cores were encapsulated by the flexible alkyl chains.Variable-temperature single-crystal X-ray diffraction and magnetic studies revealed complete thermo(T_(1/2)=233 K(2)and 237 K(3))and photo-induced electron transfer event accompanying spin transition between the diamagnetic[Fe^(Ⅱ)_(LS2)Co^(Ⅲ)_(LS2)]state and the paramagnetic[Fe^(Ⅲ)_(LS2)Co^(Ⅱ)_(HS2)]state(LS,low spin;HS,high spin).In addition,the bidirectional switching between the two states was achieved with alternating laser irradiation at 808 and 532 nm at 10 K.
基金Financial support by start-up fund from SUSTech(Nos.Y01216127 and Y01216227,ZZ)the Distinguished Expert Fund from Nanshan District of Shenzhen(No.K19219502,ZZ)+7 种基金the China Postdoctoral Science Foundation(No.2018M640226,LQ)the SUSTech Presidential Postdoctoral Fellowship(LQ)the Basic and Applied Basic Research Programs of Guangdong Provinee(No.2020A1515110990,LQ)the Post-doctorate Scientific Research Fund for staying(coming to)Shenzhen(K21217515,LQ)the Jilin Provi ncial Science Research Foun dati on of China(No.20200403154SF)Special Funds for the Cultivation of Guang-dong College Stude nts'Scie ntific and Tech no logical Inno vatio n("Climbing Program"Special Funds,pdjh2020c0034)is acknowledgedThis work was also partly sponsored by Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)the She nzhe n Nobel Prize Scie ntists Laboratory Project(No.C17783101).
文摘In this work,we screened three Grubbs catalysts and two Hoveyda-Grubbs catalysts for the production of H_(2) by dehydrogenation of formic acid(FA).The best results were achieved with the use of a first-generation Hoveyda-Grubbs catalyst.With a catalyst loading of mere 0.5μmol, a maximum TON of 36356 was obtained within 3 h.Two key intermediates were identified by using 1H NMR and high-resolution electrospray ionization mass spectroscopy(HRESI-MS),based on which a mechanism possibly responsible for the observed catalysis was proposed.
基金supported by the Major State Basic Research Development Program of China(No.2021YFB3201000)the National Natural Science Foundation of China(Grant Nos.62074066,62134003,and 12050005)+2 种基金the Fund for Innovative Research Groups of the Natural Science Foundation of Hubei Province(Nos.2021CFA036 and 2020CFA034)Shenzhen Basic Research Program(No.JCYJ20200109115212546)the Fundamental Research Funds for the Central Universities.
文摘Metal halide perovskites(MHPs)have demonstrated excellent performances in detection of X-rays and gamma-rays.Most studies focus on improving the sensitivity of single-pixel MHP detectors.However,little work pays attention to the dark current,which is crucial for the back-end circuit integration.Herein,the requirement of dark current is quantitatively evaluated as low as 10^(−9)A/cm^(2)for X-ray imagers integrated on pixel circuits.Moreover,through the semiconductor device analysis and simulation,we reveal that the main current compositions of thick perovskite X-ray detectors are the thermionic-emission current(J_(T))and the generation-recombination current(J_(g-r)).The typical observed failures of p-n junctions in thick detectors are caused by the high generation-recombination current due to the band mismatch and interface defects.This work provides a deep insight into the design of high sensitivity and low dark current perovskite X-ray detectors.
基金Project partially supported by US NSF grant CHE-1800392(AdBD)The authors thank Dr.Chad Park for assistance with the photophysical studies.We also acknowledge the Arizona Laboratory for the use of the ICP-MS supported by NIEHS Grant(P42 ES-04940-11).
文摘Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs)of the general formula{[Ln(HIDA)_(2)H_(2)O]ClO_(4)·H_(2)O}_n(Ln=La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_(2)IDA=iminodiacetic acid)and[Ln(TT)(HTT)(H_(2)O)_3]_n(Ln=Eu(7),Gd(8),Tb(9),Dy(10),and Eu:Tb(11);H_(2)TT=tartaric acid)were synthesized by reacting Ln(ClO_(4))_3 with iminodiacetic acid and L-tartaric acid,respectively.All compounds were structurally characterized by single-crystal X-ray diffraction.Elemental analyses are co nsistent with the corre sponding crystallographically generated formulas.Mo reover,the luminescence properties of both the single and mixed-lanthanide complexes were studied.Near infrared,red,and green emissions that are characteristic of Nd(Ⅲ),Eu(Ⅲ),and Tb(Ⅲ)are observed for 2,3/7,and 5/9,respectively.For the two mixed-lanthanide complex systems 6 and 11,depending on the relative amount of Eu(Ⅲ)and Tb(Ⅲ),the color of emission can be fine-tuned.It is found that a small amount of Eu(Ⅲ)is adequate for the observation of the most intense transition of Eu(Ⅲ).This is believed to be a result of energy transfer from Tb(Ⅲ)to Eu(Ⅲ)within the same complex-a conclusion supported by the significantly shortened lifetime of Tb(Ⅲ)and the accompanying enhanced lifetime of Eu(Ⅲ)in the mixedlanthanide complex with respect to the corresponding values for the pure Tb(Ⅲ)and Eu(Ⅲ)complexes with the same ligand.
基金the National Natural Science Foundation of China(22071202,21931009,and 21721001).
文摘The slow oxygen reduction process at the cathode and the scarcity of platinum-based metals lead to limited applications in fuel cells and metal-air cells.Recently,transition metal and nitrogen co-doped carbon-based catalysts(M–N–C)are regarded as the most prospective non-precious metal catalysts for future fuel cell applications.It is verified theoretically and experimentally that the metal and nitrogen coordination structure is the main catalytic activity center of oxygen reduction reaction(ORR),so constructing M–N–C materials with high available surface area and structural stability is an effective way to accelerate ORR.Herein,we deliberately synthesize a one-dimensional ZIF structure to fabricate one-dimensional porous Fe–N–C nanostick via two-step pyrolysis.Excitingly,the as-synthesized exhibited an outstanding ORR activity in alkaline medium(E_(1/2)of 0.928 V),as well as superior stability(only changed 7 mV after 10,000 cycles in alkaline medium).Our results show that the reduction of electrocatalyst dimensionality can promote mass transport and increase the accessibility of active sites,thus optimizing their performance in ORR.This work is a good demonstration of the importance of a rational design of catalyst structure for efficient ORR.
基金supported by the National Natural Science Foundation of China(92261203,22101116,22033005 and 21971106)Key Laboratory of Rare Earth Chemistry of Guangdong Higher Education Institutes(2022KSYS006)+2 种基金the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925161141006),Shenzhen Fundamental Research Program(JCYJ20220530115001002)Postdoctoral Scientific Research Fund for staying at(coming to)Shenzhen(K21217520)The calculations were performed with SUSTech supercomputer and were supported by Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.
基金supported by the National Natural Science Foundation of China(nos.21671095 and 21901108)and startup funds from SUSTech.
文摘Postsynthesis of the paramagnetic square-shaped complex{[(Tp*Me)Fe(μ-CN)_(2)(CN)][Co(dmbpy)_(2)]}_(2)(BPh_(4))_(2)·6MeCN·H2O[1,Tp*Me=tris(3,4,5-trimethylpyrazole)-borate;dmbpy=4,4′-dimethyl-2,2′-bipyridine)]by grafting transition metal(II)thiocyanates via its terminal cyano groups afforded three hexanuclear[Fe_(2)Co_(2)M_(2)]clusters(M=Zn,2;Co,3;Cd,4).The peripheral metal-complex units serving as excellent electron acceptors were found to help stabilize the low-temperature state of Fe^(II,LS)–Co^(III,LS) within the complex core.
基金supported by the National Natural Science Foundation of China(grant nos.21971117,21522106,and 51872224)China Postdoctoral Science Foundation(grant no.2018M642133)+4 种基金the National Key R&D Program of China(grant no.2017YFA0208000)the Fundamental Research Funds for the Central Universities,Nankai University(grant nos.63201071 and ZB19500202)State Key Laboratory of Rare Earth Resource Utilization(grant no.RERU2019001)the 111 Project(grant no.B18030)from ChinaBeijing-Tianjin-Hebei Collaborative Innovation Project(grant no.63201058).
文摘Hybrids composed of biocompatible polymers reinforced with inorganic nanomaterials are useful for many biomedical applications including implantation and tissue regeneration and engineering.In this work,we report a new type of hybrid prepared by doping ultrathin nanowires of lanthanide hydroxycarbonates into classical biocompatible poly(citrates-siloxane).The doping of the inorganic nanowires imparts the hybrids with excellent miscibility with the polymeric matrix,producing hybrids with high elasticity and high tensile strength.The hybrids containing Eu(III)and Gd(III)display their respective luminescence and magnetic properties and thus,offer opportunities to monitor the fate of such hybrids when used in vivo.Insignificant degradation and excellent biocompatibility of these hybrids have also been demonstrated.Together,these favorable traits portend useful applications of the newly developed hybrid elastomers.
基金supported by the National Natural Science Foundation of China(92261203,22101116,and 21971106)Key Laboratory of Rare Earth Chemistry of Guangdong Higher Education Institutes(2022KSYS006)+1 种基金the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925161141006)Shenzhen Fundamental Research Program(JCYJ20220530115001002 and JCYJ20220818100417037).
文摘Many sandwich-type lanthanide complexes show extremely high energy barriers(Ueff)for the reversal of magnetization and high blocking temperatures,being the star molecules in the research area of single-molecule magnets.Herein,the preparation,structural determination,and magnetic property studies of two ansa-bridged Er-COT(COT=cyclooctatetraenyl dianion)complexes[KDME_(2)][Er((η^(8)-COT-Si^(Me2))_(2)O)](1)and[KDME_(2)][Er((η^(8)-COT-Si^(iPr2))_(2)O)]K[Er((η^(8)-COT-Si^(iPr2))_(2)O)](2)were reported.The Er(Ⅲ)ions in both complexes are sandwiched by two COT rings which are ansa-bridged by a[Si-O-Si]group.Magnetic studies reveal both complexes display slow magnetic relaxations with comparable energy barriers(228(5)K for 1,and 196(4)K for 2)and blocking temperatures(10.5 K for both complexes).The difference in the relaxation times(τ)for the two complexes was studied in details:different molecular vibrations induced by the substituents are the main reason forτfor 1 being about 10 times longer than for 2 at the same temperature above 10 K,while the quantum tunnelling of magnetization relaxation time(τQTM)for 2 is about 10 times longer than for 1 below 8 K,probably owing to the different dipolar interactions.Further rearrangement of molecular network with such ansa-bridged SMMs is promising to design molecular magnetic materials with enhanced properties or new properties.
基金National Natural Science Foundation of China(Grant Nos.62134003,62074066,U23A20359,and 623B2033)Major State Basic Research Development Program of China(No.2021YFB3201000)+2 种基金Natural Science Foundation of Hubei Province(Nos.2021CFA036 and 2020CFA034)Shenzhen Basic Research Program(No.JCYJ20200109115212546)China National Postdoctoral for Innovative Talents Program(No.BX20240124).
文摘Direct X-ray detectors based on semiconductors have drawn great attention from researchers in the pursuing of higher imaging quality.However,many previous works focused on the optimization of detection performances but seldomly watch them in an overall view and analyze how they will influence the detective quantum efficiency(DQE)value.Here,we propose a numerical model which shows the quantitative relationship between DQE and the properties of X-ray detectors and electric circuits.Our results point out that pursuing high sensitivity only is meaningless.To reduce the medical X-ray dose by 80%,the requirement for X-ray sensitivity is only at a magnitude of 103µCGy-1·cm^(-2).To achieve the DQE=0.7 at X-ray sensitivity air from 1248 to 8171µCGy-1air·cm^(-2),the requirements on dark current density ranges from 10 to 100 nA·cm^(-2) and the fluctuation of current density should fall in 0.21 to 1.37 nA·cm^(-2).
