Silica aerogel has broad applications in the field of high-temperature thermal insulation due to its low density,low thermal conductivity and high stability.However,its thermal insulation performance deteriorates sign...Silica aerogel has broad applications in the field of high-temperature thermal insulation due to its low density,low thermal conductivity and high stability.However,its thermal insulation performance deteriorates significantly at elevated temperatures exceeding 600℃,primarily due to the collapse of pore structure.Meanwhile,the shielding capacity of SiO_(2) aerogel to the infrared radiation at high temperature is rather low due to the intrinsic properties of SiO_(2).Herein,a strategy for improving the high-temperature stability and infrared shielding properties of SiO_(2) aerogel via Ca doping was explored.Calcium-doped silica aerogel(CSA)powders were prepared by Sol-Gel,hydrothermal,and ambient pressure drying(APD)techniques using water glass and anhydrous calcium chloride as precursors and trimethylchlorosilane as a hydrophobic modifier.The effects of Ca/Si molar ratio in the precursor and hydrothermal conditions(temperature and pH)on the crystalline properties,microscopic morphology and pore structure of CSAs were investigated.The results show that the Ca/Si molar ratio and hydrothermal treatment have significant effects on the microstructure and heat resistance of CSAs in the temperature range of 400-1000℃.The samples sintered at 1000℃have a high specific surface area of 100.1 m^(2)/g and a pore volume of 0.8705 cm^(3)/g,indicating that the CSA has good heat resistance.One-side insulation tests at temperatures up to 600℃show that the sample with a Ca/Si molar ratio of 1.0 has the best insulation performance,with a cold surface temperature of 450℃,which is 27℃lower than that of the pure silica aerogel.展开更多
Developing catalysts with excellent stability while significantly reducing the overpotential of the oxygen evolution reaction(OER) is crucial for advancing overall water splitting(OWS) systems.In this study,we synthes...Developing catalysts with excellent stability while significantly reducing the overpotential of the oxygen evolution reaction(OER) is crucial for advancing overall water splitting(OWS) systems.In this study,we synthesized the electrode material Ce-NiCo-LDHs@SnO_(2)/NF through a two-step hydrothermal reaction,where Ce-doped NiCo-LDHs are grown on nickel foam modified by a SnO_(2) layer.Ce doping adjusts the internal electronic distribution of Ni Co-LDHs,while the introduction of the SnO_(2) layer enhances electron transfer capability.Together,these factors contribute to the reduction of the OER energy barrier and experimental evidence confirms that the reaction proceeds via the lattice oxygen evolution mechanism(LOM).Consequently,Ce-NiCo-LDHs@SnO_(2)/NF exhibits high level electrochemical performance in OER,requiring only 234 m V overpotential to achieve a current density of 10 m A/cm^(2),with a Tafel slope of just 27.39 m V/dec.When paired with Pt/C/NF,an external potential of only 1.54 V is needed to drive OWS to attain a current density amounting to 10 m A/cm^(2).Furthermore,the catalyst demonstrates stability for 100 h during the OWS stability test.This study underscores the feasibility of enhancing the OER performance through Ce doping and the introduction of a conductive SnO_(2) layer.展开更多
An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)an...An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)and two polarity gates(PG1 and PG2).Utilizing the polarity bias concept,a narrow N^(+)pocket is formed between the source and channel without the need for additional doping steps,achieved through biasing PG1 and PG2 at-1.2 V and 1.2 V,respectively.This method not only addresses issues related to doping control but also eliminates constraints associated with thermal budgets and simplifies the fabrication process compared to traditional TFETs.To facilitate biomolecule sensing within the device,a nanogap cavity is formed in the gate dielectric by selectively etching a section of the polarity gate dielectric layer toward the source side.The investigation into the presence of neutral and charged molecules within the cavities has been conducted by examining variations in the electrical properties of the proposed biosensor.Key characteristics assessed include drain current,energy band,and electric field distribution.The performance of the biosensor is measured using various metrics such as drain current(I_(DS)),subthreshold swing(SS),threshold voltage(V_(TH)),drain current ratio(I_(ON)/I_(OFF)).The proposed in-built N^(+)pocket ED-TFET-based biosensor reaches a peak sensitivity of 1.08×10~(13)for a neutral biomolecule in a completely filled nanogap with a dielectric constant of 12.Additionally,the effects of cavity geometry and different fill factors(FFs)on sensitivity are studied.展开更多
The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batte...The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batteries.However,its poor cycling,owing to highpressure phase transitions,is one of its disadvantages.In this study,Cu/Ti was introduced into NFM111 cathode material using a solidphase method.Through both theoretically and experimentally,this study found that Cu doping provides a higher redox potential in NFM111,improving its reversible capacity and charge compensation process.The introduction of Ti would enhance the cycling stability of the material,smooth its charge and discharge curves,and suppress its high-voltage phase transitions.Accordingly,the NaNi_(0.27)Fe_(0.28)Mn_(0.33)Cu_(0.05)Ti_(0.06)O_(2)sample used in the study exhibited a remarkable rate performance of 142.97 mAh·g^(-1)at 0.1 C(2.0-4.2 V)and an excellent capacity retention of 72.81%after 300 cycles at 1C(1C=150 mA·g^(-1)).展开更多
MnO_(2) stands out among cathode materials for aqueous zinc-ion batteries(AZIBs)high capacity and voltage,it has poor stability and slow Zn^(2+) kinetics.Herein,we propose a dual-regulation strategy integrating copper...MnO_(2) stands out among cathode materials for aqueous zinc-ion batteries(AZIBs)high capacity and voltage,it has poor stability and slow Zn^(2+) kinetics.Herein,we propose a dual-regulation strategy integrating copper doping and carbon-based confinement.Residual carbon(RC),derived from acid-washed coal gasification fine slag(CGFS),serves as a conductive and porous framework for the directional growth of Cu-doped MnO_(2) nanowires(CMO@RC).The synergistic modulation of Cu-induced electronic structure tuning and carbon confinement induced mechanical/electrical stabilization significantly enhances Zn^(2+) transport and electrochemical performance.CMO@RC achieves a high capacity of 563 mA·h·g^(−1) at 0.1 A·g^(−1) and maintains 106%after 1000 cycles at 1 A·g^(−1).Kinetic analyses confirm the dual-path Zn^(2+) diffusion and accelerated reaction kinetics,while DFT calculations reveal that Cu doping enhances Mn 3d orbital hybridization and electron interaction with carbon,elevating the density of states near the Fermi level and reducing charge transfer barriers.Furthermore,pouch cell testing demonstrates outstanding flexibility and mechanical resilience.This study provides a cost-effective and scalable strategy for high-performance AZIBs,leveraging both experimental and theoretical validations.展开更多
Electrochemical CO_(2) reduction reaction(CO_(2)RR) into valuable formate provides a strategy for carbon neutrality.Bismuth(Bi) catalysts,attributed to their appropriate energy barrier of OCHO*intermediate,have demons...Electrochemical CO_(2) reduction reaction(CO_(2)RR) into valuable formate provides a strategy for carbon neutrality.Bismuth(Bi) catalysts,attributed to their appropriate energy barrier of OCHO*intermediate,have demonstrated substantial potential for the advancement of electrocatalytic CO_(2) reduction to formate.However,due to the weak bonding of protons(H^(*)) of Bi,the available protonate of CO_(2) on Bi is insufficient,which limits the formation of OCHO^(*).Prediction by theoretical calculation,chlorine doping can effectively promote the dissociation of H_(2)O and thus achieve effective proton supply.We prepare chlorine-doped Bi(Cl-Bi) via an electrochemical conversion strategy for electroreduction of CO_(2) .An obvious improvement of faradaic efficiency(FE) of formate(96.7% at-0.95 V vs.RHE) can be achieved on Cl-Bi,higher than that of Bi(89.4%).Meanwhile,Cl-Bi has the highest formate production rate of 275 μmol h^(-1)cm^(-2)at-0.95 V vs.RHE,which is 1.2 times higher than that of Bi(224 μmol h^(-1)cm^(-2)).In situ characterizations and kinetic analysis reveal that chlorine doping promotes the activation of H_(2)O and supply sufficient protons to promote the protonation of CO_(2) to OCHO^(*),which is consistent with theoretical calculation.The study presents an effective strategy for rational design of highly efficient electrocatalysts to promote green chemical production.展开更多
We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber p...We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber provides the gain.The chaotic laser was pumped by the laser diodes with the maximum power of 150 mW at the wavelength of 850 nm.The peak fluorescence spectrum of Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber at the wavelength of 635 nm shows that the visiblewavelength fiber laser can be achieved by synergistic energy transfer between Pr~(3+)and Yb^(3+)ions.The chaotic fiber laser is generated by adjusting the pump power,polarization controller and the auto-correlation,permutation entropy,skewness,and kurtosis were used to analyze the characteristics of chaotic laser.The noise-like time series and delta-like auto-correlation curve indicate the chaotic output.The complexity and randomness of time series are analyzed by the permutation entropy,skewness,and kurtosis.The result shows that chaotic dynamics is stable when the pump power exceeds a certain value.The visible chaotic all-fiber laser has high stability and can be applied for real-time monitoring and sensing.We believe that this approach may also be feasible for other materials for emission in the visible range.展开更多
Solid oxide electrolysis cells(SOECs)can effectively convert CO_(2)into high value-added CO fuel.In this paper,Sc-doped Sr_(2)Fe_(1.5)Mo_(0.3)Sc_(0.2)O_(6−δ)(SFMSc)perovskite oxide material is synthesized via solid-p...Solid oxide electrolysis cells(SOECs)can effectively convert CO_(2)into high value-added CO fuel.In this paper,Sc-doped Sr_(2)Fe_(1.5)Mo_(0.3)Sc_(0.2)O_(6−δ)(SFMSc)perovskite oxide material is synthesized via solid-phase method as the cathode for CO_(2)electrolysis by SOECs.XRD confirms that SFMSc exhibits a stable cubic phase crystal structure.The experimental results of TPD,TG,EPR,CO_(2)-TPD further demonstrate that Sc-doping increases the concentration of oxygen vacancy in the material and the chemical adsorption capacity of CO_(2)molecules.Electrochemical tests reveal that SFMSc single cell achieves a current density of 2.26 A/cm^(2) and a lower polarization impedance of 0.32Ω·cm^(2) at 800°C under the applied voltage of 1.8 V.And no significant performance attenuation or carbon deposition is observed after 80 h continuous long-term stability test.This study provides a favorable support for the development of SOEC cathode materials with good electro-catalytic performance and stability.展开更多
The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alka...The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.展开更多
To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration signific...To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration significance and systematic research re-quirements.By utilizing the low-cost and excellent magnetic and stable chemical characteristics of barium ferrite(BaFe_(12)O_(19))and using the high dielectric loss and excellent chemical inertia of nanocarbon clusters,a new type of nanocomposites with carbon nanoclusters en-capsulating BaFe_(12)O_(19)was designed and synthesized by combining an impregnation method and a high-temperature calcination strategy.Furthermore,Ce-Mn ions were introduced into the BaFe_(12)O_(19)lattice to improve the dielectric and magnetic properties of BaFe_(12)O_(19)cores significantly,and the energy band structure of the doped lattice and the orders of Ce replacing Fe sites were calculated.Benefiting from Ce-Mn ion doping and carbon nanocluster encapsulation,the composite material exhibited excellent dual functionality of corrosion resist-ance and EWA.When BaCe_(0.2)Mn_(0.3)Fe_(11.5)O_(19)-C(BCM-C)was calcined at 600°C,the minimum reflection loss of-20.1 dB was achieved at 14.43 GHz.The Ku band’s effective absorption bandwidth of 4.25 GHz was achieved at an absorber thickness of only 1.3 mm.The BCM-C/polydimethylsiloxane coating had excellent corrosion resistance in the simulated marine environment(3.5wt%NaCl solution).The|Z|0.01Hz value of BCM-C remained at 106Ω·cm^(2)after 12 soaking days.The successful preparation of the BaFe_(12)O_(19)composite en-capsulated with carbon nanoclusters provides new insights into the preparation of multifunctional absorbent materials and the fabrication of absorbent devices applied in humid marine environments in the future.展开更多
Herein,an external crosslinker facilitated the hypercrosslinking of ferrocene and a nitrogen heterocyclic compound(either melamine or imidazole)through a direct Friedel-Crafts reaction,which led to the formation of ni...Herein,an external crosslinker facilitated the hypercrosslinking of ferrocene and a nitrogen heterocyclic compound(either melamine or imidazole)through a direct Friedel-Crafts reaction,which led to the formation of nitrogen-containing hypercrosslinked fer-rocene polymer precursors(HCP-FCs).Subsequent carbonization of these precursors results in the production of iron-nitrogen-doped por-ous carbon absorbers(Fe-NPCs).The Fe-NPCs demonstrate a porous structure comprising aggregated nanotubes and nanospheres.The porosity of this structure can be modulated by adjusting the iron and nitrogen contents to optimize impedance matching.The uniform dis-tribution of Fe-N_(x)C,N dipoles,andα-Fe within the carbon matrix can be ensured by using hypercrosslinked ferrocenes in constructing porous carbon,providing the absorber with numerous polarization sites and a conductive network.The electromagnetic wave absorption performance of the specially designed Fe-NPC-M_(2)absorbers is satisfactory,revealing a minimum reflection loss of-55.3 dB at 2.5 mm and an effective absorption bandwidth of 6.00 GHz at 2.0 mm.By utilizing hypercrosslinked polymers(HCPs)as precursors,a novel method for developing highly efficient carbon-based absorbing agents is introduced in this research.展开更多
Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium batteries.However,the poor chemical stability and compatibilit...Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium batteries.However,the poor chemical stability and compatibility with lithium metal limit their application.Herein,Li_(5.4)PS_(4.4)Cl1.4I0.2solid electrolyte with high ionic conductivity of 11.49 m S ccm^(-1)and improved chemical stability is synthesized by iodine doping.An ultra-thin Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane with thickness of 10μm can be obtained by wet coating process,exhibiting a high ionic conductivity of 2.09 mS ccm^(-1)and low areal resistance of 1.17Ωcm^(-2).Moreover,iodine doping could in-situ form LiI at the lithium/electrolyte interface and improve the critical current density of Li_(5.4)PS_(4.4)Cl_(1.6)from 0.8 to 1.35 mA cm^(-2).The resultant LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)/Li battery shows excellent cycling stability at 1 C,with a reversible specific capacity of 110.1 mA h g^(-1)and a retention of 80.5% after 1000 cycles.In addition,the assembled LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane/Li pouch cell delivers an initial discharge capacity of 110.4 mA h g^(-1)and 80.5% capacity retention after 100 cycles.展开更多
In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.How...In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.However,they are also confronted with the problem of unstable battery performance due to the heavy volume expansion and sluggish ion reaction kinetics.Herein,yolk-shell cobalt phosphosulfide nanocrystals encapsulating into multi-heterogeneous atom(N,P,S)-doped carbon framework(Co_(9)S_(8)/CoP@NPSC)were constructed by employing dodecahedral ZIF-67 as precursor and a polymer as carbon sources through simultaneous sulfidation and phosphorization processes.The synergistic effect of Co_(9)S_(8)and CoP component and the yolk-shell structure greatly improve the bettery performance and structural stability.In addition,the multiple hetero-atoms doped carbon frameworks enhance the conductivity of the electrode materials and increase the spacing of carbon layers to supply sufficient active sites and facilitate the Na^(+)/K^(+)transport.The electrochemical results demonstrated that Co_(9)S_(8)/CoP@NPSC exhibited the pleasant reversible capacity(360.47 mAh/g at 1 A/g)after 300 cycles and an unpredictable cycling stability(103.22 mAh/g after 1000 cycles)in the SIBs application.The ex-situ XRD and XPS analyses were further applied to study the sodium ion storage mechanism and the multi-step phase transition reaction of the yolk-shell heterogeneous structure.This work provides new perspectives for the preparation of novel structure metal phosphosulfide and their applications in anode materials for sodium/potassium batteries and other secondary batteries.展开更多
Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5...Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5)P_(4)catalysts on nickel foam with efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performance in alkaline media.Density Functional Theory(DFT)calculations and experimental studies have shown that Mo doping deadeneds the interaction between H and O atomic orbitals of transition state water molecules,effectively weakening the activation energy of H_(2)O dissociation.Therefore,Mo doping is favorable for enhancing HER activity with overpotential at 10 mA cm^(-2)of 93 mV and Tafel slope of 40.1 mV dec^(-1)in 1 M KOH.Besides,it exhibits high alkaline OER activity with an ultra-low overpotential of 200 mV at 10 mA cm^(-2).Moreover,this catalyst only needs 1.537 V in a dual-electrode configuration of the electrolytic cell,which is much lower than the commercial Pt/C-RuO_(2)couple(1.614 V).In addition,we have developed and constructed a solar thermoelectric generator(TEG)that is capable of floating on water.This TEG has a continuous power output and an exceptionally long lifespan,providing a stable power supply to the synthesized catalyst electrolyzer.It can produce a maximum power output of over 90 mW,meeting the requirement of converting solar radiation heat into usable electricity.As a result,the system achieves productivity of 0.11 mL min^(-1)H_(2).This solar thermal energy conversion technology shows the possibility of large-scale industrial production of H_(2)and provides a new idea for exploring heat source utilization.展开更多
It is a big challenge to tune the structure and composition of carbon-based anode materials to increase the active sites by a green synthesis strategy for potassium ion batteries(PIBs).Herein,the N/F/S co-doped three-...It is a big challenge to tune the structure and composition of carbon-based anode materials to increase the active sites by a green synthesis strategy for potassium ion batteries(PIBs).Herein,the N/F/S co-doped three-dimensional(3D)interconnected carbon nanosheets(NFS-CNSs)were synthesized from coal tar pitch(CTP)through a green and low-temperature treatment process for the first time.The as-obtained NFS-CNS600 features 3D interconnected ultra-thin carbon nanosheets with abundant active sites,tunable N/F/S species,and enlarged carbon interlayer spacing.The density functional theory calculation results demonstrate that NFS-CNSs exhibit the highest electron density and most negative K^(+)adsorption energy(-0.59 eV)compared to single or double-atom doping,thereby enhancing the storage performance of K+.As an anode for PIBs,the NFS-CNS600 exhibits good cycle stability(98.2%capacity retention after 200 cycles at 0.2 A g^(-1)),high capacity(409.1 mAh g^(-1) at 0.05 A g^(-1))and rate performance(179.5 mAh g^(-1) at 5 A g^(-1)).Besides,the NFS-CNS600 anode also displays outstanding sodium storage performance.This work offers a green strategy to synthesize CTP-based anode materials from coal chemical by-products for high-performance PIBs.展开更多
Electrocatalytic conversion of renewable biomass is emerging as a promising route for sustainable chemical production;hence it urgently calls for developing efficient electrocatalysts with low potentials and high curr...Electrocatalytic conversion of renewable biomass is emerging as a promising route for sustainable chemical production;hence it urgently calls for developing efficient electrocatalysts with low potentials and high current densities.Herein,a Pr-doped Co(OH)_(2)hexagonal sheet(Pr/Co=1/9,in mole)is synthesized by electrodeposition as highly performant catalyst for 5-hydroxymethylfurfural(HMF)oxidation reaction(HMFOR)to produce 2,5-furandicarboxylic acid(FDCA).This novel and low-cost catalyst possesses a rather low onset potential of 1.05 V(vs.RHE)and requires only 1.10 V(vs.RHE)to reach a current density of 10 mA cm^(-2)for HMFOR,significantly outperforming Co(OH)_(2)benchmark(i.e.,210 mV higher to reach10 m A cm^(-2)).The origin of Pr promotion effect as well as the evolution of CoOOH catalytic sites and HMFOR process has been deeply elucidated by physical characterizations,kinetic experiments,in situ electrochemical techniques,and theoretical calculations.The unique Pr-ameliorated CoOOH active centers enable 100%conversion of HMF,99.6%selectivity of FDCA,and 99.7%Faraday efficiency,with a superior cycling durability toward HMFOR.This can be one of the most outstanding results for Co-based HMFOR catalysts to date in the literature.Thereby this work can help open up new horizons for constructing novel and efficient Co-based electrocatalysts by the utilization of lanthanide elements.展开更多
Alloying with transition metal elements akin to Sm(CoFeCuZr)z can effectively enhance the magnetic properties of SmCo-based permanent magnets.However,the effects of transition metals doping on its magnetic properties,...Alloying with transition metal elements akin to Sm(CoFeCuZr)z can effectively enhance the magnetic properties of SmCo-based permanent magnets.However,the effects of transition metals doping on its magnetic properties,detailed atomic occupancy and the mechanism for structural stability remain unclear.Specifically,for SmCo3 magnets,there is minimal theoretical study available.Herein,based on first-principles calculations,we systematically investigated the influence of 3d transition metals(TMs)doping on the structural stability,magnetic properties and electronic characteristics of SmCo3 magnets.Our results show that Sc,Ti,V,Fe,Ni,Cu and Zn preferentially occupy the 18h lattice site,while Cr and Mn occupy the 3b and 6c lattice sites,respectively.Doping with Ti,Cr,Mn,Fe,Ni,Cu and Zn contributes to enhancing the stability of SmCo3,whereas the doping of Sc and V adversely affects structural stability.The magnetic calculations reveal that Cr,Mn and Fe doping significantly enhances the total magnetic moment.It is also found that lower concentrations of Cr doping can significantly enhance the magnetocrystalline anisotropy energy(MAE).More intriguingly,when the doping concentrations of Sc,Ni and Cu reach 14.81 at%,22.22 at%and 22.22 at%,respectively,the magnetic easy axis of the system shifts from out-of-plane to in-plane.The optimal doping concentration of Fe in the SmCo_(3) system is determined to be 37.04 at%.The Curie temperature of pure SmCo_(3) is 483.9 K.Our theoretical study offers valuable theoretical guidance for experimental exploration toward SmCo-based permanent magnets with higher performance.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.W...Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.We investigated the formation of nitrogen-induced diaph-ite structures(hybrid diamond-graphite phases)and their role in changing the conductivity.Nitrogen doping in a hy-drogen-rich plasma environment promotes the emergence of unique sp^(3)-sp^(2)bonding interfaces,where diamond grains are covalently integrated with graphitic domains,facilitating a structure-driven electronic transition.High-resolution transmis-sion electron microscopy and selected area electron diffraction reveal five-fold,six-fold and twelve-fold symmetries,along with an atypical{200}crystallographic reflection,confirming diaphite formation in 5%and 10%N-doped UNCD films,while high-er doping levels(15%and 20%)result in extensive graphitization.Raman spectroscopy tracks the evolution of sp^(2)bonding with increasing nitrogen content,while atomic force microscopy and X-ray diffraction indicate a consistent diamond grain size of~8 nm.Cryogenic electronic transport measurements reveal a conductivity increase from 8.72 to 708 S/cm as the nitrogen dop-ing level increases from 5%to 20%,which is attributed to defect-mediated carrier transport and 3D weak localization.The res-ulting conductivity is three orders of magnitude higher than previously reported.These findings establish a direct correlation between diaphite structural polymorphism and tunable electronic properties in nitrogen-doped UNCD films,offering new ways for defect-engineering diamond-based electronic materials.展开更多
We used the natural product chamomile as a carbon source to synthesize praseodymium(Pr) and nitrogen(N) co-doped biomass carbon dots(Pr/N-BCDs) with remarkable luminescence properties by one-step hydrothermal method.C...We used the natural product chamomile as a carbon source to synthesize praseodymium(Pr) and nitrogen(N) co-doped biomass carbon dots(Pr/N-BCDs) with remarkable luminescence properties by one-step hydrothermal method.Compared with single N-doped BCDs(N-BCDs) and Pr-doped BCDs(Pr-BCDs),Pr/N-BCDs not only showed better fluorescence properties and stability but also achieved a significant increase in quantum yield of 12%.More importantly,under certain conditions,Pr/N-BCDs and 2,4-dinitrophenylhydrazide(2,4-DNPH) had significant fluorescence internal filtration effect(IFE) and dynamic quenching effect,and in the concentration range of0.50-20 μmol·L^(-1),the concentration of 2,4-DNPH had a good linear relationship with the fluorescence quenching signal,and the detection limit was as low as 2.1 nmol·L^(-1).展开更多
文摘Silica aerogel has broad applications in the field of high-temperature thermal insulation due to its low density,low thermal conductivity and high stability.However,its thermal insulation performance deteriorates significantly at elevated temperatures exceeding 600℃,primarily due to the collapse of pore structure.Meanwhile,the shielding capacity of SiO_(2) aerogel to the infrared radiation at high temperature is rather low due to the intrinsic properties of SiO_(2).Herein,a strategy for improving the high-temperature stability and infrared shielding properties of SiO_(2) aerogel via Ca doping was explored.Calcium-doped silica aerogel(CSA)powders were prepared by Sol-Gel,hydrothermal,and ambient pressure drying(APD)techniques using water glass and anhydrous calcium chloride as precursors and trimethylchlorosilane as a hydrophobic modifier.The effects of Ca/Si molar ratio in the precursor and hydrothermal conditions(temperature and pH)on the crystalline properties,microscopic morphology and pore structure of CSAs were investigated.The results show that the Ca/Si molar ratio and hydrothermal treatment have significant effects on the microstructure and heat resistance of CSAs in the temperature range of 400-1000℃.The samples sintered at 1000℃have a high specific surface area of 100.1 m^(2)/g and a pore volume of 0.8705 cm^(3)/g,indicating that the CSA has good heat resistance.One-side insulation tests at temperatures up to 600℃show that the sample with a Ca/Si molar ratio of 1.0 has the best insulation performance,with a cold surface temperature of 450℃,which is 27℃lower than that of the pure silica aerogel.
基金supported by the National Natural Science Foundation of China (No.52274304)。
文摘Developing catalysts with excellent stability while significantly reducing the overpotential of the oxygen evolution reaction(OER) is crucial for advancing overall water splitting(OWS) systems.In this study,we synthesized the electrode material Ce-NiCo-LDHs@SnO_(2)/NF through a two-step hydrothermal reaction,where Ce-doped NiCo-LDHs are grown on nickel foam modified by a SnO_(2) layer.Ce doping adjusts the internal electronic distribution of Ni Co-LDHs,while the introduction of the SnO_(2) layer enhances electron transfer capability.Together,these factors contribute to the reduction of the OER energy barrier and experimental evidence confirms that the reaction proceeds via the lattice oxygen evolution mechanism(LOM).Consequently,Ce-NiCo-LDHs@SnO_(2)/NF exhibits high level electrochemical performance in OER,requiring only 234 m V overpotential to achieve a current density of 10 m A/cm^(2),with a Tafel slope of just 27.39 m V/dec.When paired with Pt/C/NF,an external potential of only 1.54 V is needed to drive OWS to attain a current density amounting to 10 m A/cm^(2).Furthermore,the catalyst demonstrates stability for 100 h during the OWS stability test.This study underscores the feasibility of enhancing the OER performance through Ce doping and the introduction of a conductive SnO_(2) layer.
基金Project supported by the Ministry of Education’s Supply and Demand Matching Employment and Education Project(Grant No.2024110776329)。
文摘An in-built N^(+)pocket electrically doped tunnel field-effect transistor(ED-TFET)-based biosensor has been reported for the first time.The proposed device begins with a PN junction structure with a control gate(CG)and two polarity gates(PG1 and PG2).Utilizing the polarity bias concept,a narrow N^(+)pocket is formed between the source and channel without the need for additional doping steps,achieved through biasing PG1 and PG2 at-1.2 V and 1.2 V,respectively.This method not only addresses issues related to doping control but also eliminates constraints associated with thermal budgets and simplifies the fabrication process compared to traditional TFETs.To facilitate biomolecule sensing within the device,a nanogap cavity is formed in the gate dielectric by selectively etching a section of the polarity gate dielectric layer toward the source side.The investigation into the presence of neutral and charged molecules within the cavities has been conducted by examining variations in the electrical properties of the proposed biosensor.Key characteristics assessed include drain current,energy band,and electric field distribution.The performance of the biosensor is measured using various metrics such as drain current(I_(DS)),subthreshold swing(SS),threshold voltage(V_(TH)),drain current ratio(I_(ON)/I_(OFF)).The proposed in-built N^(+)pocket ED-TFET-based biosensor reaches a peak sensitivity of 1.08×10~(13)for a neutral biomolecule in a completely filled nanogap with a dielectric constant of 12.Additionally,the effects of cavity geometry and different fill factors(FFs)on sensitivity are studied.
基金supported by the Low-Cost Long-Life Batteries program,China(No.WL-24-08-01)the National Natural Science Foundation of China(No.22279007)。
文摘The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batteries.However,its poor cycling,owing to highpressure phase transitions,is one of its disadvantages.In this study,Cu/Ti was introduced into NFM111 cathode material using a solidphase method.Through both theoretically and experimentally,this study found that Cu doping provides a higher redox potential in NFM111,improving its reversible capacity and charge compensation process.The introduction of Ti would enhance the cycling stability of the material,smooth its charge and discharge curves,and suppress its high-voltage phase transitions.Accordingly,the NaNi_(0.27)Fe_(0.28)Mn_(0.33)Cu_(0.05)Ti_(0.06)O_(2)sample used in the study exhibited a remarkable rate performance of 142.97 mAh·g^(-1)at 0.1 C(2.0-4.2 V)and an excellent capacity retention of 72.81%after 300 cycles at 1C(1C=150 mA·g^(-1)).
基金support from the Key projects of scientific research projects of universities in Anhui Province(2024AH050360).
文摘MnO_(2) stands out among cathode materials for aqueous zinc-ion batteries(AZIBs)high capacity and voltage,it has poor stability and slow Zn^(2+) kinetics.Herein,we propose a dual-regulation strategy integrating copper doping and carbon-based confinement.Residual carbon(RC),derived from acid-washed coal gasification fine slag(CGFS),serves as a conductive and porous framework for the directional growth of Cu-doped MnO_(2) nanowires(CMO@RC).The synergistic modulation of Cu-induced electronic structure tuning and carbon confinement induced mechanical/electrical stabilization significantly enhances Zn^(2+) transport and electrochemical performance.CMO@RC achieves a high capacity of 563 mA·h·g^(−1) at 0.1 A·g^(−1) and maintains 106%after 1000 cycles at 1 A·g^(−1).Kinetic analyses confirm the dual-path Zn^(2+) diffusion and accelerated reaction kinetics,while DFT calculations reveal that Cu doping enhances Mn 3d orbital hybridization and electron interaction with carbon,elevating the density of states near the Fermi level and reducing charge transfer barriers.Furthermore,pouch cell testing demonstrates outstanding flexibility and mechanical resilience.This study provides a cost-effective and scalable strategy for high-performance AZIBs,leveraging both experimental and theoretical validations.
基金financially supported by the Natural Science Foundation of Shandong Province (No.ZR2022QE076)the National Natural Science Foundation of China (No.52202092)the Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of China (No.2023KJ104)。
文摘Electrochemical CO_(2) reduction reaction(CO_(2)RR) into valuable formate provides a strategy for carbon neutrality.Bismuth(Bi) catalysts,attributed to their appropriate energy barrier of OCHO*intermediate,have demonstrated substantial potential for the advancement of electrocatalytic CO_(2) reduction to formate.However,due to the weak bonding of protons(H^(*)) of Bi,the available protonate of CO_(2) on Bi is insufficient,which limits the formation of OCHO^(*).Prediction by theoretical calculation,chlorine doping can effectively promote the dissociation of H_(2)O and thus achieve effective proton supply.We prepare chlorine-doped Bi(Cl-Bi) via an electrochemical conversion strategy for electroreduction of CO_(2) .An obvious improvement of faradaic efficiency(FE) of formate(96.7% at-0.95 V vs.RHE) can be achieved on Cl-Bi,higher than that of Bi(89.4%).Meanwhile,Cl-Bi has the highest formate production rate of 275 μmol h^(-1)cm^(-2)at-0.95 V vs.RHE,which is 1.2 times higher than that of Bi(224 μmol h^(-1)cm^(-2)).In situ characterizations and kinetic analysis reveal that chlorine doping promotes the activation of H_(2)O and supply sufficient protons to promote the protonation of CO_(2) to OCHO^(*),which is consistent with theoretical calculation.The study presents an effective strategy for rational design of highly efficient electrocatalysts to promote green chemical production.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61975141,61575137,and61675144)。
文摘We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser.The100-m 630 HP fibers are used to ensure high non-linearity.A 4-m Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber provides the gain.The chaotic laser was pumped by the laser diodes with the maximum power of 150 mW at the wavelength of 850 nm.The peak fluorescence spectrum of Pr^(3+)/Yb^(3+)-co-doped ZBLAN fiber at the wavelength of 635 nm shows that the visiblewavelength fiber laser can be achieved by synergistic energy transfer between Pr~(3+)and Yb^(3+)ions.The chaotic fiber laser is generated by adjusting the pump power,polarization controller and the auto-correlation,permutation entropy,skewness,and kurtosis were used to analyze the characteristics of chaotic laser.The noise-like time series and delta-like auto-correlation curve indicate the chaotic output.The complexity and randomness of time series are analyzed by the permutation entropy,skewness,and kurtosis.The result shows that chaotic dynamics is stable when the pump power exceeds a certain value.The visible chaotic all-fiber laser has high stability and can be applied for real-time monitoring and sensing.We believe that this approach may also be feasible for other materials for emission in the visible range.
基金supported by National Key R&D Program of China(2021YFB4001401)National Natural Science Foundation of China(52272190,22178023).
文摘Solid oxide electrolysis cells(SOECs)can effectively convert CO_(2)into high value-added CO fuel.In this paper,Sc-doped Sr_(2)Fe_(1.5)Mo_(0.3)Sc_(0.2)O_(6−δ)(SFMSc)perovskite oxide material is synthesized via solid-phase method as the cathode for CO_(2)electrolysis by SOECs.XRD confirms that SFMSc exhibits a stable cubic phase crystal structure.The experimental results of TPD,TG,EPR,CO_(2)-TPD further demonstrate that Sc-doping increases the concentration of oxygen vacancy in the material and the chemical adsorption capacity of CO_(2)molecules.Electrochemical tests reveal that SFMSc single cell achieves a current density of 2.26 A/cm^(2) and a lower polarization impedance of 0.32Ω·cm^(2) at 800°C under the applied voltage of 1.8 V.And no significant performance attenuation or carbon deposition is observed after 80 h continuous long-term stability test.This study provides a favorable support for the development of SOEC cathode materials with good electro-catalytic performance and stability.
基金financially supported by the project of the National Natural Science Foundation of China(52322203)the Key Research and Development Program of Shaanxi Province(2024GHZDXM-21)。
文摘The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.
基金supported by the National Key R&D Program of China(Nos.2022YFB3504804 and 2023YFF0718303)the National Natural Science Foundation of China(Nos.51871219,52071324,52031014,and 52401255)+1 种基金Science and Technology Project of Shenyang City(No.22-101-0-27)Liaoning Institute of Science and Technology Doctoral Initiation Fund Project(No.2307B19).
文摘To realize the application of electromagnetic wave absorption(EWA)devices in humid marine environments,bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration significance and systematic research re-quirements.By utilizing the low-cost and excellent magnetic and stable chemical characteristics of barium ferrite(BaFe_(12)O_(19))and using the high dielectric loss and excellent chemical inertia of nanocarbon clusters,a new type of nanocomposites with carbon nanoclusters en-capsulating BaFe_(12)O_(19)was designed and synthesized by combining an impregnation method and a high-temperature calcination strategy.Furthermore,Ce-Mn ions were introduced into the BaFe_(12)O_(19)lattice to improve the dielectric and magnetic properties of BaFe_(12)O_(19)cores significantly,and the energy band structure of the doped lattice and the orders of Ce replacing Fe sites were calculated.Benefiting from Ce-Mn ion doping and carbon nanocluster encapsulation,the composite material exhibited excellent dual functionality of corrosion resist-ance and EWA.When BaCe_(0.2)Mn_(0.3)Fe_(11.5)O_(19)-C(BCM-C)was calcined at 600°C,the minimum reflection loss of-20.1 dB was achieved at 14.43 GHz.The Ku band’s effective absorption bandwidth of 4.25 GHz was achieved at an absorber thickness of only 1.3 mm.The BCM-C/polydimethylsiloxane coating had excellent corrosion resistance in the simulated marine environment(3.5wt%NaCl solution).The|Z|0.01Hz value of BCM-C remained at 106Ω·cm^(2)after 12 soaking days.The successful preparation of the BaFe_(12)O_(19)composite en-capsulated with carbon nanoclusters provides new insights into the preparation of multifunctional absorbent materials and the fabrication of absorbent devices applied in humid marine environments in the future.
基金supported by the National Natural Science Foundation of China(No.51803041)the University and Local Integration Development Project of Yantai,China(No.2022 XDRHXMXK08).
文摘Herein,an external crosslinker facilitated the hypercrosslinking of ferrocene and a nitrogen heterocyclic compound(either melamine or imidazole)through a direct Friedel-Crafts reaction,which led to the formation of nitrogen-containing hypercrosslinked fer-rocene polymer precursors(HCP-FCs).Subsequent carbonization of these precursors results in the production of iron-nitrogen-doped por-ous carbon absorbers(Fe-NPCs).The Fe-NPCs demonstrate a porous structure comprising aggregated nanotubes and nanospheres.The porosity of this structure can be modulated by adjusting the iron and nitrogen contents to optimize impedance matching.The uniform dis-tribution of Fe-N_(x)C,N dipoles,andα-Fe within the carbon matrix can be ensured by using hypercrosslinked ferrocenes in constructing porous carbon,providing the absorber with numerous polarization sites and a conductive network.The electromagnetic wave absorption performance of the specially designed Fe-NPC-M_(2)absorbers is satisfactory,revealing a minimum reflection loss of-55.3 dB at 2.5 mm and an effective absorption bandwidth of 6.00 GHz at 2.0 mm.By utilizing hypercrosslinked polymers(HCPs)as precursors,a novel method for developing highly efficient carbon-based absorbing agents is introduced in this research.
基金National Key R&D Program of China (grant no. 2022YFB3807700)National Natural Science Foundation of China (Grant No. U1964205, U21A2075, 52172253,52102326, 52250610214, 22309194, 52372244)+4 种基金Ningbo S&T Innovation 2025 Major Special Programme (Grant No.2019B10044, 2021Z122, 2023Z106)Zhejiang Provincial Key R&D Program of China (Grant No. 2022C01072, 2024C01095)Jiangsu Provincial S&T Innovation Special Programme for carbon peak and carbon neutrality (Grant No. BE2022007)Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China (LBMHD24E020001)Youth Innovation Promotion Association CAS (Y2021080)。
文摘Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium batteries.However,the poor chemical stability and compatibility with lithium metal limit their application.Herein,Li_(5.4)PS_(4.4)Cl1.4I0.2solid electrolyte with high ionic conductivity of 11.49 m S ccm^(-1)and improved chemical stability is synthesized by iodine doping.An ultra-thin Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane with thickness of 10μm can be obtained by wet coating process,exhibiting a high ionic conductivity of 2.09 mS ccm^(-1)and low areal resistance of 1.17Ωcm^(-2).Moreover,iodine doping could in-situ form LiI at the lithium/electrolyte interface and improve the critical current density of Li_(5.4)PS_(4.4)Cl_(1.6)from 0.8 to 1.35 mA cm^(-2).The resultant LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)/Li battery shows excellent cycling stability at 1 C,with a reversible specific capacity of 110.1 mA h g^(-1)and a retention of 80.5% after 1000 cycles.In addition,the assembled LiCoO_(2)/Li_(5.4)PS_(4.4)Cl_(1.4)I_(0.2)membrane/Li pouch cell delivers an initial discharge capacity of 110.4 mA h g^(-1)and 80.5% capacity retention after 100 cycles.
基金supported by National Natural Science Foundation of China(Nos.52472194,52101243)Natural Science Foundation of Guangdong Province,China(No.2023A1515012619)the Science and Technology Planning Project of Guangzhou(No.202201010565)。
文摘In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.However,they are also confronted with the problem of unstable battery performance due to the heavy volume expansion and sluggish ion reaction kinetics.Herein,yolk-shell cobalt phosphosulfide nanocrystals encapsulating into multi-heterogeneous atom(N,P,S)-doped carbon framework(Co_(9)S_(8)/CoP@NPSC)were constructed by employing dodecahedral ZIF-67 as precursor and a polymer as carbon sources through simultaneous sulfidation and phosphorization processes.The synergistic effect of Co_(9)S_(8)and CoP component and the yolk-shell structure greatly improve the bettery performance and structural stability.In addition,the multiple hetero-atoms doped carbon frameworks enhance the conductivity of the electrode materials and increase the spacing of carbon layers to supply sufficient active sites and facilitate the Na^(+)/K^(+)transport.The electrochemical results demonstrated that Co_(9)S_(8)/CoP@NPSC exhibited the pleasant reversible capacity(360.47 mAh/g at 1 A/g)after 300 cycles and an unpredictable cycling stability(103.22 mAh/g after 1000 cycles)in the SIBs application.The ex-situ XRD and XPS analyses were further applied to study the sodium ion storage mechanism and the multi-step phase transition reaction of the yolk-shell heterogeneous structure.This work provides new perspectives for the preparation of novel structure metal phosphosulfide and their applications in anode materials for sodium/potassium batteries and other secondary batteries.
基金supported by the Hainan Provincial Natural Science Foundation of China(Nos.522MS038 and 522QN282)the National Natural Science Foundation of China(Nos.52172086 and 52301268)the Start-up Research Foundation of Hainan University(No.KYQD(ZR)-22019).
文摘Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future.In this work,we prepared porous nanosheet Mo doping Ni_(5)P_(4)catalysts on nickel foam with efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performance in alkaline media.Density Functional Theory(DFT)calculations and experimental studies have shown that Mo doping deadeneds the interaction between H and O atomic orbitals of transition state water molecules,effectively weakening the activation energy of H_(2)O dissociation.Therefore,Mo doping is favorable for enhancing HER activity with overpotential at 10 mA cm^(-2)of 93 mV and Tafel slope of 40.1 mV dec^(-1)in 1 M KOH.Besides,it exhibits high alkaline OER activity with an ultra-low overpotential of 200 mV at 10 mA cm^(-2).Moreover,this catalyst only needs 1.537 V in a dual-electrode configuration of the electrolytic cell,which is much lower than the commercial Pt/C-RuO_(2)couple(1.614 V).In addition,we have developed and constructed a solar thermoelectric generator(TEG)that is capable of floating on water.This TEG has a continuous power output and an exceptionally long lifespan,providing a stable power supply to the synthesized catalyst electrolyzer.It can produce a maximum power output of over 90 mW,meeting the requirement of converting solar radiation heat into usable electricity.As a result,the system achieves productivity of 0.11 mL min^(-1)H_(2).This solar thermal energy conversion technology shows the possibility of large-scale industrial production of H_(2)and provides a new idea for exploring heat source utilization.
基金the financial supports from the National Natural Science Foundation of China(Nos.52372037 and52072002)the Outstanding Scientific Research and Innovation Team Program of Higher Education Institutions of Anhui Province(No.2023AH010015)+1 种基金the Excellent Young Talents Fund Program of Higher Education Institutions of Anhui Province(No.2023AH030026)the financial support from the Anhui International Research Center of Energy Materials Green Manufacturing and Biotechnology.
文摘It is a big challenge to tune the structure and composition of carbon-based anode materials to increase the active sites by a green synthesis strategy for potassium ion batteries(PIBs).Herein,the N/F/S co-doped three-dimensional(3D)interconnected carbon nanosheets(NFS-CNSs)were synthesized from coal tar pitch(CTP)through a green and low-temperature treatment process for the first time.The as-obtained NFS-CNS600 features 3D interconnected ultra-thin carbon nanosheets with abundant active sites,tunable N/F/S species,and enlarged carbon interlayer spacing.The density functional theory calculation results demonstrate that NFS-CNSs exhibit the highest electron density and most negative K^(+)adsorption energy(-0.59 eV)compared to single or double-atom doping,thereby enhancing the storage performance of K+.As an anode for PIBs,the NFS-CNS600 exhibits good cycle stability(98.2%capacity retention after 200 cycles at 0.2 A g^(-1)),high capacity(409.1 mAh g^(-1) at 0.05 A g^(-1))and rate performance(179.5 mAh g^(-1) at 5 A g^(-1)).Besides,the NFS-CNS600 anode also displays outstanding sodium storage performance.This work offers a green strategy to synthesize CTP-based anode materials from coal chemical by-products for high-performance PIBs.
基金National Natural Science Foundation of China(No.22272149,22062025)Yunnan University’s Research Innovation Fund for Graduate Students(No.KC-23234085)+1 种基金Workstation of Academician Chen Jing of Yunnan Province(No.202105AF150012)Free Exploration Fund for Academician(No.202405AA350001)。
文摘Electrocatalytic conversion of renewable biomass is emerging as a promising route for sustainable chemical production;hence it urgently calls for developing efficient electrocatalysts with low potentials and high current densities.Herein,a Pr-doped Co(OH)_(2)hexagonal sheet(Pr/Co=1/9,in mole)is synthesized by electrodeposition as highly performant catalyst for 5-hydroxymethylfurfural(HMF)oxidation reaction(HMFOR)to produce 2,5-furandicarboxylic acid(FDCA).This novel and low-cost catalyst possesses a rather low onset potential of 1.05 V(vs.RHE)and requires only 1.10 V(vs.RHE)to reach a current density of 10 mA cm^(-2)for HMFOR,significantly outperforming Co(OH)_(2)benchmark(i.e.,210 mV higher to reach10 m A cm^(-2)).The origin of Pr promotion effect as well as the evolution of CoOOH catalytic sites and HMFOR process has been deeply elucidated by physical characterizations,kinetic experiments,in situ electrochemical techniques,and theoretical calculations.The unique Pr-ameliorated CoOOH active centers enable 100%conversion of HMF,99.6%selectivity of FDCA,and 99.7%Faraday efficiency,with a superior cycling durability toward HMFOR.This can be one of the most outstanding results for Co-based HMFOR catalysts to date in the literature.Thereby this work can help open up new horizons for constructing novel and efficient Co-based electrocatalysts by the utilization of lanthanide elements.
基金supported by the National Key Research and Development Program of China(No.2022YFB3505301)the National Key Research and Development Program of Shanxi Province(No.202302050201014)+2 种基金the National Natural Science Foundation of China(No.12304148)the Natural Science Basic Research Program of Shanxi Province(No.202203021222219)the China Postdoctoral Science Foundation(No.2023M731452).
文摘Alloying with transition metal elements akin to Sm(CoFeCuZr)z can effectively enhance the magnetic properties of SmCo-based permanent magnets.However,the effects of transition metals doping on its magnetic properties,detailed atomic occupancy and the mechanism for structural stability remain unclear.Specifically,for SmCo3 magnets,there is minimal theoretical study available.Herein,based on first-principles calculations,we systematically investigated the influence of 3d transition metals(TMs)doping on the structural stability,magnetic properties and electronic characteristics of SmCo3 magnets.Our results show that Sc,Ti,V,Fe,Ni,Cu and Zn preferentially occupy the 18h lattice site,while Cr and Mn occupy the 3b and 6c lattice sites,respectively.Doping with Ti,Cr,Mn,Fe,Ni,Cu and Zn contributes to enhancing the stability of SmCo3,whereas the doping of Sc and V adversely affects structural stability.The magnetic calculations reveal that Cr,Mn and Fe doping significantly enhances the total magnetic moment.It is also found that lower concentrations of Cr doping can significantly enhance the magnetocrystalline anisotropy energy(MAE).More intriguingly,when the doping concentrations of Sc,Ni and Cu reach 14.81 at%,22.22 at%and 22.22 at%,respectively,the magnetic easy axis of the system shifts from out-of-plane to in-plane.The optimal doping concentration of Fe in the SmCo_(3) system is determined to be 37.04 at%.The Curie temperature of pure SmCo_(3) is 483.9 K.Our theoretical study offers valuable theoretical guidance for experimental exploration toward SmCo-based permanent magnets with higher performance.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
文摘Nitrogen doping in chemical vapor deposition-derived ultrananocrystalline diamond(UNCD)films in-creases the electronic conductivity,yet its microstructural effects on electron transport are insufficiently understood.We investigated the formation of nitrogen-induced diaph-ite structures(hybrid diamond-graphite phases)and their role in changing the conductivity.Nitrogen doping in a hy-drogen-rich plasma environment promotes the emergence of unique sp^(3)-sp^(2)bonding interfaces,where diamond grains are covalently integrated with graphitic domains,facilitating a structure-driven electronic transition.High-resolution transmis-sion electron microscopy and selected area electron diffraction reveal five-fold,six-fold and twelve-fold symmetries,along with an atypical{200}crystallographic reflection,confirming diaphite formation in 5%and 10%N-doped UNCD films,while high-er doping levels(15%and 20%)result in extensive graphitization.Raman spectroscopy tracks the evolution of sp^(2)bonding with increasing nitrogen content,while atomic force microscopy and X-ray diffraction indicate a consistent diamond grain size of~8 nm.Cryogenic electronic transport measurements reveal a conductivity increase from 8.72 to 708 S/cm as the nitrogen dop-ing level increases from 5%to 20%,which is attributed to defect-mediated carrier transport and 3D weak localization.The res-ulting conductivity is three orders of magnitude higher than previously reported.These findings establish a direct correlation between diaphite structural polymorphism and tunable electronic properties in nitrogen-doped UNCD films,offering new ways for defect-engineering diamond-based electronic materials.
基金supported by the National Natural Science Foundation of China (Grant No.22063010)the Natural Science Foundation of Shaanxi Province (Grant No.2022QFY07-05)Yan'an Science and Technology Plan Project (Grants No.2022SLJBZ-002, 2023-CYL-193)。
文摘We used the natural product chamomile as a carbon source to synthesize praseodymium(Pr) and nitrogen(N) co-doped biomass carbon dots(Pr/N-BCDs) with remarkable luminescence properties by one-step hydrothermal method.Compared with single N-doped BCDs(N-BCDs) and Pr-doped BCDs(Pr-BCDs),Pr/N-BCDs not only showed better fluorescence properties and stability but also achieved a significant increase in quantum yield of 12%.More importantly,under certain conditions,Pr/N-BCDs and 2,4-dinitrophenylhydrazide(2,4-DNPH) had significant fluorescence internal filtration effect(IFE) and dynamic quenching effect,and in the concentration range of0.50-20 μmol·L^(-1),the concentration of 2,4-DNPH had a good linear relationship with the fluorescence quenching signal,and the detection limit was as low as 2.1 nmol·L^(-1).
