查看更多>>摘要：Plastics are one of the most produced synthetic materials and largest commodities,used in numerous sectors of human life.To upcycle waste plastics into value-added chemicals is a global challenge.Despite significant progress in pyrolysis and hydrocracking,which mainly leads to the formation of pyrolysis oil,catalytic upcycling to value-added aromatics,including benzene,toluene and xylene(BTX),in one step,is still limited by high reaction temperatures(＞500℃)and a low yield.We report herein CO2-facilitated upcycling of polyolefins and their plastic products to aromatics below 300℃,enabled by a bifunctional Pt/MnOx-ZSM-5 catalyst.ZSM-5 catalyzes cracking of polyolefins and aromatization,generating hydrogen at the same time,while Pt/MnOx catalyzes the reaction of hydrogen with CO2,consequently driving the reaction towards aromatization.Isotope experiments reveal that 0.2 kg CO2 is consumed per 1.0 kg polyethylene and 90％of the consumed CO2 is incorporated into the aromatic products.Furthermore,this new process yields 0.63 kg aromatics(BTX accounting for 60％),comparing favorably with the conventional pyrolysis or hydrocracking processes,which produce only 0.33 kg aromatics.In this way,both plastic waste and the greenhouse gas CO2 are turned into carbon resources,providing a new strategy for combined waste plastics upcycling and carbon dioxide utilization.
查看更多>>摘要：Enhancing the quality of junctions is crucial for optimizing carrier extraction and suppressing recombination in semiconductor devices.In recent years,metal halide perovskite has emerged as the most promising next-generation material for optoelectronic devices.However,the construction of high-quality perovskite junctions,as well as characterization and understanding of their carrier polarity and density,remains a challenge.In this study,using combined electrical and spectroscopic characterization techniques,we investigate the doping characteristics of perovskite films by remote molecules,which is corroborated by our theoretical simulations indicating Schottky defects consisting of double ions as effective charge dopants.Through a post-treatment process involving a combination of biammonium and monoammonium molecules,we create a surface layer of n-type low-dimensional perovskite.This surface layer forms a heterojunction with the underlying 3D perovskite film,resulting in a favorable doping profile that enhances carrier extraction.The fabricated device exhibits an outstanding open-circuit voltage(Voc)up to 1.34 V and achieves a certified efficiency of 19.31％for single-junction wide-bandgap(1.77 eV)perovskite solar cells,together with significantly enhanced operational stability,thanks to the improved separation of carriers.Furthermore,we demonstrate the potential of this wide-bandgap device by achieving a certified efficiency of 27.04％and a Voc of 2.12 V in a perovskite/perovskite tandem solar cell configuration.
查看更多>>摘要：Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques,in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field.The Peterlin-Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization,but such a material is not yet reported.Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite.A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude,till 3.0 × 10-4 m V-2.This finding enables an ultra-low operational electric field of 102-104 V m-1 and the fabrication of electro-optical devices with an inch-level electrode separation,which has not previously been practical.Because of its high ultraviolet stability(decay＜1％under ultraviolet exposure for 1000 hours),large-scale production,and energy efficiency,prototypical displayable billboards have been fabricated for outdoor interactive scenes.This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.
查看更多>>摘要：It is crucial to prepare high-mobility organic polycrystalline film through solution processing.However,the delocalized carrier transport of polycrystalline films in organic semiconductors has rarely been investigated through Hall-effect measurement.This study presents a strategy for building strong intermolecular interactions to fabricate solution-crystallized p-type perylene diimide(PDI)dianion films with a closer intermolecular π-π stacking distance of 3.25 Å.The highly delocalized carriers enable a competitive Hall mobility of 3 cm2 V-1 s-1,comparable to that of the reported high-mobility organic single crystals.The PDI dianion films exhibit a high electrical conductivity of 17 S cm-1 and typical band-like transport,as evidenced by the negative temperature linear coefficient of mobility proportional to T-3/2.This work demonstrates that,as the intermolecular π-π interactions become strong enough,they will display high mobility and conductivity,providing a new approach to developing high-mobility organic semiconductor materials.
查看更多>>摘要：The limited lifespan of batteries is a challenge in the application of implantable electronic devices.Existing wireless power technologies such as ultrasound,near-infrared light and magnetic fields cannot charge devices implanted in deep tissues,resulting in energy attenuation through tissues and thermal generation.Herein,an ultra-low frequency magnetic energy focusing(ULFMEF)methodology was developed for the highly effective wireless powering of deep-tissue implantable devices.A portable transmitter was used to output the low-frequency magnetic field(＜50 Hz),which remotely drives the synchronous rotation of a magnetic core integrated within the pellet-like implantable device,generating an internal rotating magnetic field to induce wireless electricity on the coupled coils of the device.The ULFMEF can achieve energy transfer across thick tissues(up to 20 cm)with excellent transferred power(4-15 mW)and non-heat effects in tissues,which is remarkably superior to existing wireless powering technologies.The ULFMEF is demonstrated to wirelessly power implantable micro-LED devices for optogenetic neuromodulation,and wirelessly charged an implantable battery for programmable electrical stimulation on the sciatic nerve.It also bypassed thick and tough protective shells to power the implanted devices.The ULFMEF thus offers a highly advanced methodology for the generation of wireless powered biodevices.
查看更多>>摘要：Hierarchical self-assembly with long-range order above centimeters widely exists in nature.Mimicking similar structures to promote reaction kinetics of electrochemical energy devices is of immense interest,yet remains challenging.Here,we report a bottom-up self-assembly approach to constructing ordered mesoporous nanofibers with a structure resembling vascular bundles via electrospinning.The synthesis involves self-assembling polystyrene(PS)homopolymer,amphiphilic diblock copolymer,and precursors into supramolecular micelles.Elongational dynamics of viscoelastic micelle solution together with fast solvent evaporation during electrospinning cause simultaneous close packing and uniaxial stretching of micelles,consequently producing polymer nanofibers consisting of oriented micelles.The method is versatile for the fabrication of large-scale ordered mesoporous nanofibers with adjustable pore diameter and various compositions such as carbon,SiO2,TiO2 and WO3.The aligned longitudinal mesopores connected side-by-side by tiny pores offer highly exposed active sites and expedite electron/ion transport.The assembled electrodes deliver outstanding performance for lithium metal batteries.
查看更多>>摘要：Catalytic oxidative desulfurization(ODS)using titanium silicate catalysts has emerged as an efficient technique for the complete removal of organosulfur compounds from automotive fuels.However,the precise control of highly accessible and stable-framework Ti active sites remains highly challenging.Here we reveal for the first time by using density functional theory calculations that framework hexa-coordinated Ti(TiO6)species of mesoporous titanium silicates are the most active sites for ODS and lead to a lower-energy pathway of ODS.A novel method to achieve highly accessible and homogeneously distributed framework TiO6 active single sites at the mesoporous surface has been developed.Such surface framework TiO6 species exhibit an exceptional ODS performance.A removal of 920 ppm of benzothiophene is achieved at 60℃ in 60 min,which is 1.67 times that of the best catalyst reported so far.For bulky molecules such as 4,6-dimethyldibenzothiophene(DMDBT),it takes only 3 min to remove 500 ppm of DMDBT at 60℃ with our catalyst,which is five times faster than that with the current best catalyst.Such a catalyst can be easily upscaled and could be used for concrete industrial application in the ODS of bulky organosulfur compounds with minimized energy consumption and high reaction efficiency.
查看更多>>摘要：Photocatalytic N2 fixation is a promising strategy for ammonia(NH3)synthesis;however,it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability.Herein,an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst.The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron.Within the heterojunction,the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation,cooperatively reducing the energy barrier for N2 activation.In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure,an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved.This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.
查看更多>>摘要：Precise and efficient therapy of malignant tumors is always a challenge.Herein,gold nanoclusters co-modified by aggregation-induced-emission(AIE)molecules,copper ion chelator(acylthiourea)and tumor-targeting agent(folic acid)were fabricated to perform AIE-guided and tumor-specific synergistic therapy with great spatio-temporal controllability for the targeted elimination and metastasis inhibition of malignant tumors.During therapy,the functional gold nanoclusters(AuNTF)would rapidly accumulate in the tumor tissue due to the enhanced permeability and retention effect as well as folic acid-mediated tumor targeting,which was followed by endocytosis by tumor cells.After that,the overexpressed copper ions in the tumor cells would trigger the aggregation of these intracellular AuNTF via a chelation process that not only generated the photothermal agent in situ to perform the tumor-specific photothermal therapy damaging the primary tumor,but also led to the copper deficiency of tumor cells to inhibit its metastasis.Moreover,the copper ions were reduced to cuprous ions along with the chelation,which further catalysed the excess H2O2 in the tumor cells to produce cytotoxic reactive oxygen species,resulting in additional chemodynamic therapy for enhanced antitumor efficiency.The aggregation of AuNTF also activated the AIE molecules to present fluorescence,which not only imaged the therapeutic area for real-time monitoring of this tumor-specific synergistic therapy,but also allowed us to perform near-infrared radiation at the correct time point and location to achieve optimal photothermal therapy.Both in vitro and in vivo results revealed the strong tumor elimination,effective metastasis inhibition and high survival rate of tumor-bearing mice after treatment using the AuNTF nanoclusters,indicating that this AIE-guided and tumor-specific synergistic strategy could offer a promising approach for tumor therapy.
查看更多>>摘要：Relaxation processes are crucial for understanding the structural rearrangements of liquids and amorphous materials.However,the overarching principle that governs these processes across vastly different materials remains an open question.Substantial analysis has been carried out based on the motions of individual particles.Here,as an alternative,we propose viewing the global configuration as a single entity.We introduce a global order parameter,namely the inherent structure minimal displacement(IS Dmin),to quantify the variability of configurations by a pattern-matching technique.Through atomic simulations of seven model glass-forming liquids,we unify the influences of temperature,pressure and perturbation time on the relaxation dissipation,via a scaling law between the mechanical damping factor and IS Dmin.Fundamentally,this scaling reflects the curvature of the local potential energy landscape.Our findings uncover a universal origin of glassy relaxation and offer an alternative approach to studying disordered systems.
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