This paper reports the chemical synthesis of tungsten carbide/cobalt (WC/Co) nanocomposite powders via a unique chemical processing technique, involving the using of all water soluble solution of W-, Co- and C-precurs...This paper reports the chemical synthesis of tungsten carbide/cobalt (WC/Co) nanocomposite powders via a unique chemical processing technique, involving the using of all water soluble solution of W-, Co- and C-precursors. In the actual synthesis, large quantities of commercial-scale WC-Co nanocomposite powders are made by an unique combination of converting a molecularly mixed W-, Co-, and C-containing solutions into a complex inorganic polymeric powder precursor, conversion of the inorganic polymeric precursor powder into a W-Co-C-O containing powder intermediates using a belt furnace with temperature at about 500°C - 600°C in an inert atmosphere, followed by carburization in a rotary furnace at temperature less than 1000°C in nitrogen. Liquid phase sintering technique is used to consolidate the WC/Co nanocomposite powder into sintered bulk parts. The sintered parts have excellent hardness in excess of 93 HRA, with WC grains in the order of 200 - 300 nm, while Co phase is uniformly distributed on the grain boundaries of the WC nanoparticles. We also report the presence of cobalt Co precipitates inside tungsten carbide WC nanograins in the composites of the consolidated bulk parts. EDS is used to identify the presence of these precipitates and micro-micro-diffraction technique is employed to determine the nature of these precipitates.展开更多
The Furong pluton,located in central Hunan,China,hosts numerous tungsten veins within and around the granite,which are of great economic significance.However,its petrogenesis and related mineralization are poorly cons...The Furong pluton,located in central Hunan,China,hosts numerous tungsten veins within and around the granite,which are of great economic significance.However,its petrogenesis and related mineralization are poorly constrained.In this study,we used U−Pb dating,petrological and geochemical methods to ascertain the emplacement time,classification of granitic rock,nature of the source rocks,formation mechanism,and its geodynamic implications for the Furong pluton.It is shown that the granite is precisely determined to be formed at~210 Ma,and belongs to the moderately-fractionated S-type granite.Combined with regional tectonic setting,it is concluded that the pluton was formed due to crust extension and thinning followed by plate collision and compression in South China.It is also revealed that tungsten mineralization and Indosinian granites exhibit a close temporal,spatial and genetic relationships,and further exploration of tungsten deposits within and around the granite in central Hunan,even in South China,is urgently needed.展开更多
W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical prop...W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical properties of W-CoFeNi WHAs was investigated.The experimental results show that near-spherical W grains are distributed in CoFeNi ternary multi-principal-elements alloy(MPEA)with the formation of W-richμphase in all W-CoFeNi WHAs.The volume fractions ofμphase and average W grain size increase with sintering temperatures changing from 1480 to 1560℃.The activation energy for W grain growth is significantly higher than that of traditional W-Ni-Fe and W-Ni-Co WHAs,which indicates grain coarsening behavior in CoFeNi MPEA became more difficult compared to the conventional binder alloys.W-CoFeNi sintered at 1480℃exhibits the highest yield strength of 698 MPa among all WHAs due to finer W grain size.The compressive strength and fracture strain of W-CoFeNi reduce when sintering temperatures rise from 1480 to 1560℃.展开更多
Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),wit...Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),with its well-defined tunnel structure,holds great promise as a negative electrode material for NH^(4+)storage.However,its practical application is hindered by structural instability and poor intrinsic electrical conductivity.To address these challenges,a dual-regulation strategy is proposed,integrating molybdenum(Mo)doping and NH^(4+)pre-intercalation to concurrently optimize the tunnel structure and electronic environment of h-WO_(3)(Mo-NWO).Comprehensive experimental and theoretical analyses reveal that Mo doping narrows the bandgap of WO_(3)and reduces the diffusion energy barrier,thereby accelerating NH^(4+)adsorption and diffusion.Simultaneously,NH^(4+)pre-intercalation stabilizes the tunnel framework via hydrogen bonding,ensuring structural reversibility.As expected,the Mo-NWO/AC electrode achieves a high areal capacitance of 13.6 F cm^(−2)at 5 mA cm^(−2)and retains 80.14%of its capacitance after 5000 cycles,demonstrating exceptional rate capability and cycling stability.Moreover,the assembled Mn_(3)O_(4)//Mo-NWO/AC device delivers a high energy density of 3.41 mWh cm^(−2)and outstanding long-term stability(85.75%retention after 12,000 cycles).This work provides a viable strategy for designing high-performance NH^(4+)storage materials and advances the development of sustainable energy storage systems.展开更多
In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and propert...In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.展开更多
Surface icing and fouling pose a substantial threat to marine facilities.Herein,anti-icing coating composites(F/S-WC-n%/F)with high photo-thermal conversion efficiencies were prepared by spraying a small amount of sup...Surface icing and fouling pose a substantial threat to marine facilities.Herein,anti-icing coating composites(F/S-WC-n%/F)with high photo-thermal conversion efficiencies were prepared by spraying a small amount of super-hydrophobic tungsten carbide on fluoro-olefin vinyl ether copolymer(FEVE)at a specific pressure.The photo-thermal properties of the coatings provide them with ice melting and sterilization effects.The delayed icing time of F/S-WC-5%/F is 571 s,with the ice-covered-surface temperature increasing to 42°C after exposure to simulated sunlight.Heat transfer modelling calculations show that icing needs to overcome high Gibbs free energy on F/S-WC-5%/F.Quantum chemistry fundamentally reveals a weak thermodynamic effect of water nucleation on F/S-WC-5%/F,indicating that the icing process requires a high degree of sub-cooling,resulting in delayed icing.In addition,F/S-WC-5%/F can resist different types of fouling and exhibit sterilization activity.Using F/S-WC-5%/F,Escherichia coli germs are killed via heat-induced morphological rupture under a solar simulator.Owing to its excellent environmental versatility,sustainability,mechanical durability and material adaptability,F/S-WC-5%/F is a promising anti-icing and anti-fouling candidate for various practical applications,even in harsh environments.展开更多
LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific dopin...LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific doping process and existing form of W are still not perfect.This study proposes a lithium-induced grain boundary phase W doping mechanism.The results demonstrate that the introduced W atomsfirst react with the lithium source to generate a Li–W–O phase at the grain boundary of primary particles.With the increase of lithium ratio,W atoms gradually diffuse from the grain boundary phase to the interior layered structure to achieve W doping.The feasibility of grain boundary phase doping is verified byfirst principles calculation.Furthermore,it is found that the Li2WO4 grain boundary phase is an excellent lithium ion conductor,which can protect the cathode surface and improve the rate performance.The doped W can alleviate the harmful H2↔H3 phase transition,thereby inhibiting the generation of microcracks,and improving the electrochemical performance.Consequently,the 0.3 wt%W-doped sample provides a significant improved capacity retention of 88.5%compared with the pristine LNO(80.7%)after 100 cycles at 2.8–4.3 V under 1C.展开更多
Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability mak...Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.展开更多
Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of ...Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.展开更多
The effects of potassium(K)doping on the incipient plasticity of tungsten(W)under nanoindentation were investigated using a combination of experiments and mesoscale defects dynamic simulations.The transmission electro...The effects of potassium(K)doping on the incipient plasticity of tungsten(W)under nanoindentation were investigated using a combination of experiments and mesoscale defects dynamic simulations.The transmission electron microscopy study reveal that nanometer-sized bubbles were formed through the vaporization of K in specimens prepared by spark plasma sintering.In order to investigate the mechanical properties of the K-doped W specimens,nano-characterization experiments and defect dynamics simula-tions were conducted,comparing with those in pure W.Nanoindentation tests reveal that the maximum shear yield stress approaches the theoretical strength in annealed pure W,while K-doped W samples exhibit significant yield drop accompanied with stochastic variations.A newly developed mesoscale defect dynamics model to concurrently couple dislocation dynamics with finite element method has been also employed to investigate micro-mechanisms of plasticity under nanoindentation and the effects of K-bubbles on the plastic deformation.The simulations revealed that the localized stress concentration induced by the K-bubbles promoted dislocation nucleation and enhanced plastic deformation,thereby reducing the yield stress,showing good agreement with the experiment.展开更多
Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies ...Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies between 1 keV and 150 keV.The results indicate that a smaller grain size leads to more defects forming in grain boundary regions during cascade processes.The impact of high-energy PKA may cause a certain degree of distortion of the grain boundaries,which has a higher probability in systems with smaller grain sizes and becomes more pronounced as the PKA energy increases.The direction of PKA can affect the formation and diffusion pathways of defects.When the PKA direction is perpendicular to the grain boundary,defects preferentially form near the grain boundary regions;by contrast,defects are more inclined to form in the interior of the grains.These results are of great significance for comprehending the changes in the performance of polycrystalline W under the high-energy fusion environments and can provide theoretical guidance for further optimization and application of W-based plasma materials.展开更多
A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary...A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary motion of the tungsten needle trans-ferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow charac-teristics.The influences of tungsten electrode rotation speed on PAW arc morphology,weld formation and interfacial microstructure of the final weld joints were discussed by the experimental procedures involving in-situ ablation,surfacing and butt welding.The ex-periments were conducted on Q235B steel.The results indicated that the increase of tungsten electrode rotation speed in PAW-RT contributed to improving arc eccentricity,leading to aesthetically improved welds with more uniformity.Additionally,the strength,hardness and toughness of the welded joint increased,while porosity was reduced.展开更多
The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding t...The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.展开更多
The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The result...The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The results revealed that phosphotungstic acid exhibited a strong affinity for TBP with decreasing TBP concentration.Higher acidity significantly improved the W extraction efficiency with TBP,and the lower Cl^(-)concentration reduced the extraction efficiency of Fe.As the organic phase approached saturation point,phosphotungstic acid competitively displaced Fe to combine with TBP.The hydrogen bond structure(P=O·HO-P-W-O)between phosphotungstic acid and TBP was characterized by FT-IR,and the salting-out effect induced by FeCl_(3) was elucidated.In summary,high acidity is beneficial for exhaustive extraction of W,and an effective W/Fe separation can be achieved by reducing the concentrations of TBP and Cl^(-).展开更多
The photochemical conversion of plastic waste into valuable resources under ambient conditions is challenging.Achieving efficient photocatalytic conversion necessitates intimate contact between the photocatalyst and p...The photochemical conversion of plastic waste into valuable resources under ambient conditions is challenging.Achieving efficient photocatalytic conversion necessitates intimate contact between the photocatalyst and plastic substrate,as water molecules are readily oxidized by photogenerated holes,potentially bypassing the plastic as the electron donor.This study demonstrated a novel strategy for depositing polystyrene(PS)waste onto a photoanode by leveraging its solubility in specific organic solvents,including acetone and chloroform,thus enhancing the interface contact.We used an anodization technique to fabricate a skeleton-like porous tungsten oxide(WO_(3))structure,which exhibited higher durability against detachment from a conductive substrate than the WO_(3) photoanode fabricated using the doctor blade method.Upon illumination,the photogenerated holes were transferred from WO_(3) to PS,promoting the oxidative degradation of plastic waste under ambient conditions.Consequently,the oxidative degradation of PS on the anode side generated carbon dioxide,while the cathodic process produced hydrogen gas through water reduction.Our findings pave the way for sunlight-driven plastic waste treatment technologies that concurrently generate valuable fuels or chemicals and offer the dual benefits of cost savings and environmental protection.展开更多
Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing m...Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.展开更多
Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic de...Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic devices.However,the performance of TMDs-based devices is hampered by the suboptimal quality of metal electrodes contacting the atomically thin TMDs layers.Understanding the mechanisms that influence contact quality is crucial for advancing TMDs devices.In this study,we investigated the conductive properties of tungsten selenide(WSe_(2))-based devices with different film thicknesses.Using the transmission line method,a negative correlation between contact resistance and film thickness in multi-electrode devices was revealed.Additionally,repeatability tests conducted at varied temperatures indicated enhanced device stability with increasing film thickness.Theoretical analysis,supported by thermionic emission theory and thermal simulations,suggests that the degradation in electrical properties is primarily due to the thermal effect at the contact interface.Furthermore,we found that van der Waals contacts could mitigate the thermal effect through a metal transfer method.Our findings elucidate the critical role of contact resistance in the electronic performance of 2D material-based field-effect transistors(FETs),which further expands their potential in the next generation of electronic and optoelectronic devices.展开更多
Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-dope...Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.展开更多
Environmentally friendly lead-free relaxor ferroelectric ceramics with outstanding energy storage performance have become a key research direction for advanced pulsed power systems due to their ultrafast discharge spe...Environmentally friendly lead-free relaxor ferroelectric ceramics with outstanding energy storage performance have become a key research direction for advanced pulsed power systems due to their ultrafast discharge speed and high energy density.However,the development of environmentally friendly,leadfree energy storage ceramics faces multiple critical challenges,such as low breakdown strength,low energy storage density,and low efficiency.To address these issues,we developed a novel lead-free TTBs relaxor ferroelectric ceramic,Bi_(0.15)Na_(0.15)Sr_(0.3)Ba_(0.4)Nb_2O_6-1 wt%C_(6)H_(5)O_(7)Na_(3),achieving a W_(rec)of 9.53 J cm^(-3)and an ultra-highηof 92%at 730 kV cm^(-1).This represents a significant breakthrough in the performance of lead-free TTBs energy storage ceramics.By incorporating C_(6)H_(5)O_(7)Na_(3),we effectively suppressed the concentration of oxygen vacancy defects,inhibited abnormal grain growth,and formed dense grain boundaries to prevent defect diffusion under external stimulation.These modifications enhance energy storage performance and excellent stability.This finding not only validate an optimization strategy for TTBs-based dielectric capacitors but also introduce C_(6)H_(5)O_(7)Na_(3) into the lead-free relaxor ferroelectric ceramic system.In summary,this work establishes a new design paradigm integrating'leadfree composition,high performance,and high stability'characteristics,providing crucial technological support for applying lead-free energy storage ceramics in pulse power systems and next-generation energy storage applications.展开更多
Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance...Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.展开更多
文摘This paper reports the chemical synthesis of tungsten carbide/cobalt (WC/Co) nanocomposite powders via a unique chemical processing technique, involving the using of all water soluble solution of W-, Co- and C-precursors. In the actual synthesis, large quantities of commercial-scale WC-Co nanocomposite powders are made by an unique combination of converting a molecularly mixed W-, Co-, and C-containing solutions into a complex inorganic polymeric powder precursor, conversion of the inorganic polymeric precursor powder into a W-Co-C-O containing powder intermediates using a belt furnace with temperature at about 500°C - 600°C in an inert atmosphere, followed by carburization in a rotary furnace at temperature less than 1000°C in nitrogen. Liquid phase sintering technique is used to consolidate the WC/Co nanocomposite powder into sintered bulk parts. The sintered parts have excellent hardness in excess of 93 HRA, with WC grains in the order of 200 - 300 nm, while Co phase is uniformly distributed on the grain boundaries of the WC nanoparticles. We also report the presence of cobalt Co precipitates inside tungsten carbide WC nanograins in the composites of the consolidated bulk parts. EDS is used to identify the presence of these precipitates and micro-micro-diffraction technique is employed to determine the nature of these precipitates.
基金financially supported by the Natural Key Research and Development Program of China(No.2023YFC2906801)the National Natural Science Foundation of China(No.42102073)the Open Protect Fund of State Key Laboratory of Critical Mineral Research and Exploration,China(No.202308)。
文摘The Furong pluton,located in central Hunan,China,hosts numerous tungsten veins within and around the granite,which are of great economic significance.However,its petrogenesis and related mineralization are poorly constrained.In this study,we used U−Pb dating,petrological and geochemical methods to ascertain the emplacement time,classification of granitic rock,nature of the source rocks,formation mechanism,and its geodynamic implications for the Furong pluton.It is shown that the granite is precisely determined to be formed at~210 Ma,and belongs to the moderately-fractionated S-type granite.Combined with regional tectonic setting,it is concluded that the pluton was formed due to crust extension and thinning followed by plate collision and compression in South China.It is also revealed that tungsten mineralization and Indosinian granites exhibit a close temporal,spatial and genetic relationships,and further exploration of tungsten deposits within and around the granite in central Hunan,even in South China,is urgently needed.
基金Funded by the National Natural Science Foundation of China(Nos.52404378 and 52371019)the Basic Scientific Research Project of Liaoning Provincial Education Department(No.JYTQN2023009)the Dalian Science&Technology Innovation Foundation Project(No.2024JJ11PT003)。
文摘W-CoFeNi WHAs(tungsten heavy alloys)were fabricated by powder metallurgy with sintering temperatures ranging from 1480 to 1560℃.The influence of sintering temperatures on microstructure evolutions and mechanical properties of W-CoFeNi WHAs was investigated.The experimental results show that near-spherical W grains are distributed in CoFeNi ternary multi-principal-elements alloy(MPEA)with the formation of W-richμphase in all W-CoFeNi WHAs.The volume fractions ofμphase and average W grain size increase with sintering temperatures changing from 1480 to 1560℃.The activation energy for W grain growth is significantly higher than that of traditional W-Ni-Fe and W-Ni-Co WHAs,which indicates grain coarsening behavior in CoFeNi MPEA became more difficult compared to the conventional binder alloys.W-CoFeNi sintered at 1480℃exhibits the highest yield strength of 698 MPa among all WHAs due to finer W grain size.The compressive strength and fracture strain of W-CoFeNi reduce when sintering temperatures rise from 1480 to 1560℃.
基金supported by the National Natural Science Foundation of Guangxi Province(2024GXNSFBA010033)the Special Fund for Science and Technology Development of Guangxi(Grant No.AD25069078).
文摘Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),with its well-defined tunnel structure,holds great promise as a negative electrode material for NH^(4+)storage.However,its practical application is hindered by structural instability and poor intrinsic electrical conductivity.To address these challenges,a dual-regulation strategy is proposed,integrating molybdenum(Mo)doping and NH^(4+)pre-intercalation to concurrently optimize the tunnel structure and electronic environment of h-WO_(3)(Mo-NWO).Comprehensive experimental and theoretical analyses reveal that Mo doping narrows the bandgap of WO_(3)and reduces the diffusion energy barrier,thereby accelerating NH^(4+)adsorption and diffusion.Simultaneously,NH^(4+)pre-intercalation stabilizes the tunnel framework via hydrogen bonding,ensuring structural reversibility.As expected,the Mo-NWO/AC electrode achieves a high areal capacitance of 13.6 F cm^(−2)at 5 mA cm^(−2)and retains 80.14%of its capacitance after 5000 cycles,demonstrating exceptional rate capability and cycling stability.Moreover,the assembled Mn_(3)O_(4)//Mo-NWO/AC device delivers a high energy density of 3.41 mWh cm^(−2)and outstanding long-term stability(85.75%retention after 12,000 cycles).This work provides a viable strategy for designing high-performance NH^(4+)storage materials and advances the development of sustainable energy storage systems.
基金supported by National Natural Science Foundation of China(52175305)National Natural Science Foundation of China(U22B20127)Taishan Scholars Project(tstp20230618).
文摘In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.
基金supported by the Heilongjiang Province Key Research and Development Program(No.2023ZX07D04)the Fundamental Research Funds for Central Universities and the State Key Laboratory of Marine Coating.
文摘Surface icing and fouling pose a substantial threat to marine facilities.Herein,anti-icing coating composites(F/S-WC-n%/F)with high photo-thermal conversion efficiencies were prepared by spraying a small amount of super-hydrophobic tungsten carbide on fluoro-olefin vinyl ether copolymer(FEVE)at a specific pressure.The photo-thermal properties of the coatings provide them with ice melting and sterilization effects.The delayed icing time of F/S-WC-5%/F is 571 s,with the ice-covered-surface temperature increasing to 42°C after exposure to simulated sunlight.Heat transfer modelling calculations show that icing needs to overcome high Gibbs free energy on F/S-WC-5%/F.Quantum chemistry fundamentally reveals a weak thermodynamic effect of water nucleation on F/S-WC-5%/F,indicating that the icing process requires a high degree of sub-cooling,resulting in delayed icing.In addition,F/S-WC-5%/F can resist different types of fouling and exhibit sterilization activity.Using F/S-WC-5%/F,Escherichia coli germs are killed via heat-induced morphological rupture under a solar simulator.Owing to its excellent environmental versatility,sustainability,mechanical durability and material adaptability,F/S-WC-5%/F is a promising anti-icing and anti-fouling candidate for various practical applications,even in harsh environments.
基金supported by the National Natural Science Foundation of China(No.52122407,No.52174285,52404317)the Science and Technology Innovation Program of Hunan Province(No.2022RC3048).
文摘LiNiO_(2)(LNO)is one of the most promising cathode materials for lithium-ion batteries.Tungsten element in enhancing the stability of LNO has been researched extensively.However,the understanding of the specific doping process and existing form of W are still not perfect.This study proposes a lithium-induced grain boundary phase W doping mechanism.The results demonstrate that the introduced W atomsfirst react with the lithium source to generate a Li–W–O phase at the grain boundary of primary particles.With the increase of lithium ratio,W atoms gradually diffuse from the grain boundary phase to the interior layered structure to achieve W doping.The feasibility of grain boundary phase doping is verified byfirst principles calculation.Furthermore,it is found that the Li2WO4 grain boundary phase is an excellent lithium ion conductor,which can protect the cathode surface and improve the rate performance.The doped W can alleviate the harmful H2↔H3 phase transition,thereby inhibiting the generation of microcracks,and improving the electrochemical performance.Consequently,the 0.3 wt%W-doped sample provides a significant improved capacity retention of 88.5%compared with the pristine LNO(80.7%)after 100 cycles at 2.8–4.3 V under 1C.
基金National Natural Science Foundation of China(52071165,52475347)National Program of Foreign Experts of China(G2023026003L)+4 种基金China Postdoctoral Fund(2023M740475)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(22HASTIT026)Program for the Top Young Talents of Henan Province,China,Frontier Exploration Projects of Longmen Laboratory,China(LMQYTSKT016)Key Scientific Research Projects of Colleges and Universities in Henan Province,China(24A460008)Key Science and Technology Project of Henan Province,China(242102220064,222102230111)。
文摘Tungsten/molybdenum alloys are widely utilized in the nuclear industry,aerospace and various other fields due to their high melting points and strength characteristics.However,poor sinterability and processability make it difficult to manufacture largesize or complex-shaped parts.Hence,an in-depth study on the welding technology of tungsten/molybdenum alloys is urgent.An introduction of tungsten/molybdenum alloy welding defects and joining process was provided,along with recent advancements in brazing,spark plasma sintering diffusion bonding,electron beam welding and laser beam welding.The latest progress in alloy doping treatment applied to tungsten/molybdenum alloy dissimilar welding was also discussed,and existing welding problems were pointed out.The development prospects of weldability of tungsten/molybdenum alloy by various joining technologies were forecasted,thereby furnishing a theoretical and practical found.
文摘Practical application of Na_(3)SbS_(4)(NSS)solid-state electrolyte in sodium metal batteries has been significantly hindered by poor interfacial stability and insufficient ionic conductivity.In this study,a series of dual-site doped Na_(3-2x)Sb_(1-x)W_(x)S_(4-x)F_(x)(x=0,0.12,0.24,0.36)electrolytes through high-energy ball milling followed by high-temperature sintering is prepared,where tungsten(W)substitutes for antimony(Sb)and fluorine(F)replaces sulfur(S)in the NSS lattice.The co-doping of W and F not only broadens the interplanar spacing of NSS but also promotes the stable formation of the cubic phase of NSS,thereby effectively enhancing the transport ability of sodium ions within NSS.Among them,Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24) exhibits the highest ionic conductivity of 4.45 mS·cm^(-1).Furthermore,F doping facilitates the in-situ formation of NaF between the electrolyte and metallic sodium,significantly improving interfacial stability.Electrochemical evaluation shows that the Na/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na symmetric cell achieves a high critical current density of 1.65 mA·cm^(-2) and maintains stable sodium plating/stripping cycling for 500 h at 0.1 mA·cm^(-2).Additionally,the TiS2/Na_(2.52)Sb_(0.76)W_(0.24)S_(3.76)F_(0.24)/Na full cell exhibits outstanding cycling stability and rate capability.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(No.RS-2024-00445448)the National Research Foundation of Korea(NRF)funded by the Ministry of Science(No.NRF-2021R1A2C3005096)the ITER Technology R&D Program.
文摘The effects of potassium(K)doping on the incipient plasticity of tungsten(W)under nanoindentation were investigated using a combination of experiments and mesoscale defects dynamic simulations.The transmission electron microscopy study reveal that nanometer-sized bubbles were formed through the vaporization of K in specimens prepared by spark plasma sintering.In order to investigate the mechanical properties of the K-doped W specimens,nano-characterization experiments and defect dynamics simula-tions were conducted,comparing with those in pure W.Nanoindentation tests reveal that the maximum shear yield stress approaches the theoretical strength in annealed pure W,while K-doped W samples exhibit significant yield drop accompanied with stochastic variations.A newly developed mesoscale defect dynamics model to concurrently couple dislocation dynamics with finite element method has been also employed to investigate micro-mechanisms of plasticity under nanoindentation and the effects of K-bubbles on the plastic deformation.The simulations revealed that the localized stress concentration induced by the K-bubbles promoted dislocation nucleation and enhanced plastic deformation,thereby reducing the yield stress,showing good agreement with the experiment.
基金Project supported by the National MCF Energy Research and Development Program of China(Grant No.2018YFE0308101)the National Key Research and Development Program of China(Grant No.2018YFB0704000)+1 种基金the Suqian Science and Technology Program(Grant No.K202337)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.23KJD490001).
文摘Using molecular dynamics methods,simulations of collision cascades in polycrystalline tungsten(W)have been conducted in this study,including different primary-knock-on atom(PKA)directions,grain sizes,and PKA energies between 1 keV and 150 keV.The results indicate that a smaller grain size leads to more defects forming in grain boundary regions during cascade processes.The impact of high-energy PKA may cause a certain degree of distortion of the grain boundaries,which has a higher probability in systems with smaller grain sizes and becomes more pronounced as the PKA energy increases.The direction of PKA can affect the formation and diffusion pathways of defects.When the PKA direction is perpendicular to the grain boundary,defects preferentially form near the grain boundary regions;by contrast,defects are more inclined to form in the interior of the grains.These results are of great significance for comprehending the changes in the performance of polycrystalline W under the high-energy fusion environments and can provide theoretical guidance for further optimization and application of W-based plasma materials.
基金supported by the National Natural Science Foundation of China(U22B20127)the National Natural Science Foundation of China(52175305)Taishan Scholars Project(tstp20230618).
文摘A high-quality welding method,named plasma arc welding apparatus with rotating tungsten electrode(abbreviated as PAW-RT),was proposed in this paper.The rotation speed could be adjusted from 0 to 15000 r/min.The rotary motion of the tungsten needle trans-ferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow charac-teristics.The influences of tungsten electrode rotation speed on PAW arc morphology,weld formation and interfacial microstructure of the final weld joints were discussed by the experimental procedures involving in-situ ablation,surfacing and butt welding.The ex-periments were conducted on Q235B steel.The results indicated that the increase of tungsten electrode rotation speed in PAW-RT contributed to improving arc eccentricity,leading to aesthetically improved welds with more uniformity.Additionally,the strength,hardness and toughness of the welded joint increased,while porosity was reduced.
基金supported by the Collaborative Innovation Program of Hefei Science Center of CAS(No.2022HSC-CIP007)。
文摘The thermal conductivity of plasma-facing materials(PFM)exposed to intense radiation is a critical concern for the reliable usage of materials in fusion reactors.However,limited research has been performed regarding the thermal conductivity of structures that rapidly change in a short time during collision cascade processes under irradiation.In this study,we employed the tight-binding(TB)method to investigate the electronic thermal conductivity(κ_(e))of tungsten-based systems during various cascading processes.We found thatκ_(e) values sharply decrease within the initial 0.3 picoseconds and then partially recover at a slow pace;this is closely linked to the evolution of defects and microstructural distortions.The increase in the initial kinetic energy of the primary knock-on atom and the presence of a high concentration of hydrogen atoms further decrease theκ_(e) values.Conversely,higher temperatures have a significant positive effect onκ_(e).Furthermore,the presence of a grain boundary∑5[001](130)substantially reducesκ_(e),whereas the absorption effect of point defects by the grain boundary has little influence onκ_(e) during cascades.Our findings provide a theoretical basis for evaluating changes in the thermal conductivity performance of PFMs during their usage in nuclear fusion reactors.
基金supported by the National key R&D Program of China(No.2022YFC2905105)the National Natural Science Foundation of China(No.72088101)。
文摘The distribution and competitive behaviors of phosphotungstic acid and ferric chloride in the TBP-HCl-H_(2)O system were investigated by controlling the extractant concentration and the solution environment.The results revealed that phosphotungstic acid exhibited a strong affinity for TBP with decreasing TBP concentration.Higher acidity significantly improved the W extraction efficiency with TBP,and the lower Cl^(-)concentration reduced the extraction efficiency of Fe.As the organic phase approached saturation point,phosphotungstic acid competitively displaced Fe to combine with TBP.The hydrogen bond structure(P=O·HO-P-W-O)between phosphotungstic acid and TBP was characterized by FT-IR,and the salting-out effect induced by FeCl_(3) was elucidated.In summary,high acidity is beneficial for exhaustive extraction of W,and an effective W/Fe separation can be achieved by reducing the concentrations of TBP and Cl^(-).
基金supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science and Information and Communication Technology(ICT)(NRF-2020M3H4A3106354)Korea Government(MSIT,RS-2023-00213022)the Korea Institution of Science and Technology(KIST)internal projects.
文摘The photochemical conversion of plastic waste into valuable resources under ambient conditions is challenging.Achieving efficient photocatalytic conversion necessitates intimate contact between the photocatalyst and plastic substrate,as water molecules are readily oxidized by photogenerated holes,potentially bypassing the plastic as the electron donor.This study demonstrated a novel strategy for depositing polystyrene(PS)waste onto a photoanode by leveraging its solubility in specific organic solvents,including acetone and chloroform,thus enhancing the interface contact.We used an anodization technique to fabricate a skeleton-like porous tungsten oxide(WO_(3))structure,which exhibited higher durability against detachment from a conductive substrate than the WO_(3) photoanode fabricated using the doctor blade method.Upon illumination,the photogenerated holes were transferred from WO_(3) to PS,promoting the oxidative degradation of plastic waste under ambient conditions.Consequently,the oxidative degradation of PS on the anode side generated carbon dioxide,while the cathodic process produced hydrogen gas through water reduction.Our findings pave the way for sunlight-driven plastic waste treatment technologies that concurrently generate valuable fuels or chemicals and offer the dual benefits of cost savings and environmental protection.
基金supported by the National Natural Science Foundation of China(Nos.22374119 and 22274127)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2021-QZ-01)+1 种基金the Key Project of Natural Science Fund of Shaanxi Province(Nos.2023-JC-ZD-06 and 2024JC-YBQN-0636)the Open Project of the State Key Laboratory of Transducer Technology(No.SKT2307).
文摘Wearable sensors are pivotal for point-of-care diagnostics,yet their application in extreme conditions is rarely conducted.In this work,we present a wearable pH sensor using tungsten oxide aerogel(TOA)as the sensing material.With the advantages of large specific surface area,high porosity and interconnected network structures,TOA not only provides excellent pH sensing performance but also demonstrates remarkable structural and sensing stability.The potentiometric pH sensor exhibits a high sensitivity(−63.70 mV/pH),a low detectable limit(0.05)and a superior stability(maintained over 50,000 s).Integrated with a Bluetooth module,the wearable sensor achieves non-invasive and real-time pH monitoring on the human skin with minimal deviation(1.91%)compared to the commercial pH meter.More importantly,the anti-impact behaviors of the TOA-based sensing materials and chip,along with the pH wearable sensor on a pig exhibit an outstanding shock-resistance ability,with variations no more than 7.17%under an impact of 118.38 kPa.Therefore,this study shows great promise for the aerogel-based personalized health management in the extreme environment.
基金supported by the Science and Technology Innovation Council of Shenzhen(No.KQTD20170810105439418)the National Key R&D Project from Minister of Science and Technology,China(No.2021YFB3200304)+2 种基金National Natural Science Foundation of China(Nos.6237129,52125205,U20A20166,61805015 and 61804011)the Natural Science Foundation of Beijing Municipality(No.Z180011)the Fundamental Research Funds for the Central Universities.
文摘Semiconducting transition-metal dichalcogenides(TMDs)have garnered significant interest due to their unique structures and properties,positioning them as promising candidates for novel electronic and optoelectronic devices.However,the performance of TMDs-based devices is hampered by the suboptimal quality of metal electrodes contacting the atomically thin TMDs layers.Understanding the mechanisms that influence contact quality is crucial for advancing TMDs devices.In this study,we investigated the conductive properties of tungsten selenide(WSe_(2))-based devices with different film thicknesses.Using the transmission line method,a negative correlation between contact resistance and film thickness in multi-electrode devices was revealed.Additionally,repeatability tests conducted at varied temperatures indicated enhanced device stability with increasing film thickness.Theoretical analysis,supported by thermionic emission theory and thermal simulations,suggests that the degradation in electrical properties is primarily due to the thermal effect at the contact interface.Furthermore,we found that van der Waals contacts could mitigate the thermal effect through a metal transfer method.Our findings elucidate the critical role of contact resistance in the electronic performance of 2D material-based field-effect transistors(FETs),which further expands their potential in the next generation of electronic and optoelectronic devices.
文摘Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.
基金supported by the National Natural Science Foundation of China(U23A20605 and 52201173)the S&T Program of Hebei(22567627H)+3 种基金the Henan key Laboratory of Aeronautical Materials and Application Technology Open fund(ZHKF-230113)the Opening Project of State Key Laboratory of Metastable Materials Science and Technology(202513)the Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021301)the Fundamental Research Funds for the Central Universities(2024GFYD002)。
文摘Environmentally friendly lead-free relaxor ferroelectric ceramics with outstanding energy storage performance have become a key research direction for advanced pulsed power systems due to their ultrafast discharge speed and high energy density.However,the development of environmentally friendly,leadfree energy storage ceramics faces multiple critical challenges,such as low breakdown strength,low energy storage density,and low efficiency.To address these issues,we developed a novel lead-free TTBs relaxor ferroelectric ceramic,Bi_(0.15)Na_(0.15)Sr_(0.3)Ba_(0.4)Nb_2O_6-1 wt%C_(6)H_(5)O_(7)Na_(3),achieving a W_(rec)of 9.53 J cm^(-3)and an ultra-highηof 92%at 730 kV cm^(-1).This represents a significant breakthrough in the performance of lead-free TTBs energy storage ceramics.By incorporating C_(6)H_(5)O_(7)Na_(3),we effectively suppressed the concentration of oxygen vacancy defects,inhibited abnormal grain growth,and formed dense grain boundaries to prevent defect diffusion under external stimulation.These modifications enhance energy storage performance and excellent stability.This finding not only validate an optimization strategy for TTBs-based dielectric capacitors but also introduce C_(6)H_(5)O_(7)Na_(3) into the lead-free relaxor ferroelectric ceramic system.In summary,this work establishes a new design paradigm integrating'leadfree composition,high performance,and high stability'characteristics,providing crucial technological support for applying lead-free energy storage ceramics in pulse power systems and next-generation energy storage applications.
基金supported by the Fundamental Re-search Funds for the Central Universities(Ganglong Cui)and National Key Research and Development Pro-gram of China(No.2021YFA1500703 to Ganglong Cui)National Natural Science Foundation of China(No.22103067 to Xiao-Ying Xie)and Natural Science Foundation of Shandong Province(No.ZR2021QB105 to Xiao-Ying Xie).
文摘Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.
