Recent Advances in Fibrous Materials for Hydroelectricity Generation

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis.Fibrous materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first introduced.Then,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are demonstrated.Afterward,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in detail.Moreover,the potential applications including power supply,energy storage,electrical sensor,and information expression are also discussed.Finally,some existing challenges are considered and prospects for future development are sincerely proposed.

Unfolding the structure-property relationships of Li_(2)S anchoring on two-dimensional materials with high-throughput calculations and machine learning

Lithium-sulfur(Li-S)batteries are notable for their high theoretical energy density,but the‘shuttle effect’and the limited conversion kinetics of Li-S species can downgrade their actual performance.An essential strategy is to design anchoring materials(AMs)to appropriately adsorb Li-S species.Herein,we propose a new three-procedure protocol,named InfoAd(Informative Adsorption)to evaluate the anchoring of Li_(2)S on two-dimensional(2D)materials and disclose the underlying importance of material features by combining high-throughput calculation workflow and machine learning(ML).In this paradigm,we calculate the anchoring of Li_(2)S on 12552D A_(x)B_(y)(B in the VIA/VIIA group)materials and pick out 44(un)reported nontoxic 2D binary A_(x)B_(y)AMs,in which the importance of the geometric features on the anchoring effect is revealed by ML for the first time.We develop a new Infograph model for crystals to accurately predict whether a material has a moderate binding with Li_(2)S and extend it to all 2D materials.Our InfoAd protocol elucidates the underlying structure-property relationship of Li_(2)S adsorption on 2D materials and provides a general research framework of adsorption-related materials for catalysis and energy/substance storage.

Density Functional Theory Study on the First Hyperpolarizabilities of Mono-and Bimetal Ir(Ⅰ)/Rh(Ⅰ)2,2'-Bidipyrrins Complexes

Metal complexes with excellent nonlinear optical（NLO） properties have attracted considerable attention. The geometry structure, electronic spectra and NLO properties of 2,2？-bidipyrrins（L） and mono-and bimetal Ir（I）/Rh（I）–L complexes have been investigated by density functional theory method. Our calculations revealed that L with planar configuration shows the largest first hyperpolarizability value, which is 2.2 to 5.5 times larger than that of others. It is attributed to the single direction of intramolecular charge transfer. When metal ions were embedded in ligands, the first hyperpolarizability values of mono-and bimetal Ir/Rh（I）–L complexes were smaller than that of L, and that of bimetal Ir/Rh（I）–L complexes were smaller than the corresponding monometallic Ir/Rh（I）–L. This is caused by the intramolecular charge transfer from multiple directions as well as the amount of charge transfer. On the other hand, on increasing the number of metal ions, the charge transfer in the opposite direction cancels each other more obviously. Our work would provide some theoretical reference for the second-order NLO responses of mono-and bimetal complexes.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-Ⅱ Photo-Immunotherapy of Metastatic Tumor

Massive efforts have been concentrated on the advance of eminent near-infrared(NIR) photothermal materials(PTMs) in the NIR-Ⅱ window(1000–1700 nm), especially organic PTMs because of their intrinsic biological safety compared with inorganic PTMs. However, so far, only a few NIR-Ⅱresponsive organic PTMs was explored, and their photothermal conversion efficiencies(PCEs) still remain relatively low. Herein, donor–acceptor conjugated diradical polymers with open-shell characteristics are explored for synergistically photothermal immunotherapy of metastatic tumors in the NIR-Ⅱ window. By employing side-chain regulation, the conjugated diradical polymer TTB-2 with obvious NIR-Ⅱ absorption was developed, and its nanoparticles realize a record-breaking PCE of 87.7% upon NIR-Ⅱ light illustration. In vitro and in vivo experiments demonstrate that TTB-2 nanoparticles show good tumor photoablation with navigation of photoacoustic imaging in the NIR-Ⅱ window, without any side-effect. Moreover, by combining with PD-1 antibody,the pulmonary metastasis of breast cancer is high-effectively prevented by the efficient photo-immunity effect. Thus, this study explores superior PTMs for cancer metastasis theranostics in the NIR-Ⅱ window, offering a new horizon in developing radical-characteristic NIR-Ⅱ photothermal materials.

Exploration of Earth-Abundant Transition Metals(Fe,Co,Ni)Doped on W_(18)O_(49)System as Electrocatalysts for Urea Productiont

The conversion of inert N_(2)and CO_(2)into urea by electrocatalytic technology not only reduces the cost of urea synthesis in future,but also alleviatesthe environmental pollution problem caused by carbon emission in traditional industrial production.However,facing downside factors such as strong competitive reactions and unclear reaction mechanism,the design of high-performance urea catalysts is imminent.This study demonstrates that W_(18)O_(49)system doped heteronuclear metals(TM=Fe,Co,Ni)can effectively solve the problem of competitive adsorption between N_(2)and CO_(2)and realize the co-adsorption of N_(2)and CO_(2)at diverse sites.Their theoretical limiting voltages for urea production on TM-W_(18)O_(49)(TM=Fe,Co,Ni)systems are-0.46 V,-0.42 V and-0.52 V,respectively.The results are all lower than that of the contrastive voltage in pristine W_(18)O_(49)system(-0.91 V),further indicating the rationality and necessity of single-atom doped strategy for the co-reduction of two molecules.Specially,Co-W_(18)O_(49)can theoretically inhibit the side reactions of NRR,CO_(2)RR,and HER,which deserve future experimental exploration in future.The study suggests that doping heteronuclear metal into transition metal oxides is a feasible scheme to solve competitive adsorption and improve catalytic performance.

Room-temperature synthesis of full-component APbX_(3)perovskite nanocrystal inks for optoelectronic applications

Lead halide perovskite nanocrystals(PNCs)have received great research interests due to their excellent optoelectronic properties.However,high temperature,inert gas protection and insulating long-chain ligands are used during the conventional hot-injection synthesis of PNCs,which limits their practical applications.In this work,we first develop a simple and scalable polar-solvent-free method for the preparation of full-component APbX_(3)(A=Cs,methylammonium(MA),formamidinium(FA),X=Cl,Br,I)PNCs under ambient condition.Through an exothermic reaction between butylamine(BA)and propionic acid(PA)short ligands,the PbX_(2) precursors could be well dissolved without use of any polar solvent.Meanwhile,the relatively lower growth rate of PNCs in our room-temperature reaction enables us to modulate the synthetic procedure to enhance the scalability(40-fold)and achieve large-scale synthesis.The resultant short ligands passivated PNC inks are compatible with varying solution depositing technique like spray coating for large-area film.Finally,we showcase that adopting the as-prepared MAPbI_(3) PNC inks,a self-powered photodetector is fabricated and shows a high photoresponsivity.These results demonstrate that our ambient-condition synthetic approach can accelerate the preparation of tunable and ready-to-use PNCs towards commercial optoelectronic applications.

Biphase-to-monophase structure evolution of Na_(0.766+x)Li_(x)Ni_(0.33-x)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) toward ultradurable Na-ion batteries

Layered composite oxide materials with O3/P2 biphasic crystallographic structure typically demonstrate a combination of high capacities of the O3 phase and high operation voltages of the P2 phase.However,their practical applications are seriously obstructed by difficulties in thermodynamic phase regulation,complicated electrochemical phase transition,and unsatisfactory cycling life.Herein,we propose an efficient structural evolution strategy from biphase to monophase of Na_(0.766+x)Li_(x)Ni_(0.33-x)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) through Li+substitution.The role of Li+substitution not only simplifies the unfavorable phase transition by altering the local coordination of transition metal(TM)cations but also stabilizes the cathode–electrolyte interphase to prevent the degradation of TM cations during battery cycling.As a result,the thermodynamically robust O_(3)-Na_(0.826)Li_(0.06)Ni_(0.27)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) cathode delivers a high capacity of 139.4 mAh g^(-1) at 0.1 C and shows prolonged cycling life at high rates,with capacity retention of 81.6%at 5 C over 500 cycles.This work establishes a solid relationship between the thermodynamic structure evolution and electrochemistry of layered cathode materials,contributing to the development of long-life sodium-ion batteries.

Deposition technologies of perovskite layer enabling large-area photovoltaic modules

The commercialization of perovskite solar cells(PSCs)is expected.However,the selection of fabrication technology remains unclear,especially with different technologies corresponding to different area ranges.This study presents a summary of recent technologies related to device area and photovoltaic parameters for certain area ranges.Blade-coating,slot-die coating,and bar-coating technologies are suitable for PSCs whose area is greater than or equal to 100 cm^(2).Meanwhile,meniscus-coating,spray-coating,and roll-to-roll technologies are appropriate for flexible large-area PSCs.The definition of large area has been updated to one above 10 cm^(2).In conclusion,we provide a perspective for future large-area perovskite photovoltaics.

Theoretical Studies on Reaction Mechanisms of HNCS with NH(X^3Σ)

The reaction mechanisms of HNCS with NH（X^3∑ ） were theoretically investigated. The minimum energy paths （MEP） of the reaction were calculated by using the density functional theory（DFT） at the B3LYP/6-311 ＋ ＋ G^＊＊ level. The equilibrium structural parameters, the harmonic vibrational frequencies, the total energies, and the zeropoint energies（ZPE） of all the species were calculated. The single-point energies along the MEP were further refined at the QCISD（T）/6-311 ＋ ＋ G^＊ ＊ level. It was found that the mechanisms of the HNCS ＋ NH（X^3∑） reaction involve two channels producing the HNC ＋ HNS and the N2H2 ＋ CS products. Channel 1 plays a dominant role and the HNC ＋ HNS are the main preduets. The reaction is exothermie.

Luminescent properties of Ca_2SiO_4:Eu^(3+) red phosphor for trichromatic white light emitting diodes

The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.

Bi nanoparticles in situ encapsulated by carbon film as high-performance anode materials for Li-ion batteries

Bismuth (Bi) has indeed inspired great interests in lithium-ion batteries (LIBs) due to the high capacity,but was still limited by the low electrical conductivity and large volume variation.Herein,a composite material based on Bi nanoparticles in situ encapsulated by carbon film (Bi@CF) is prepared successfully through a facile metal–organic framework (MOF)-engaged approach.As anode materials for LIBs,the Bi@CF composites achieved high reversible capacities of 705 and 538 mAh g^(-1)at 0.2 and 0.5 A g^(-1) after200 cycles,and long cycling performance with a stable capacity of 306 mAh g^(-1)at 1.0 A g^(-1) even after 900 cycles.In situ X-ray diffraction (XRD) measurements clearly revealed the conversion between Bi and Li_(3)Bi during the alloying/dealloying process,confirming the good electrochemical reversibility of Bi@CF for Li-storage.The reaction kinetics of this Bi@CF composite was further studied by galvanostatic intermittent titration technique (GITT).This work may provide an inspiration for the elaborate design and facile preparation of alloy-type anode materials for high-performance rechargeable batteries.

Recent progress in electronic modulation of electrocatalysts for high-efficient polysulfide conversion of Li-S batteries

With the merits of high energy density,environmental friendliness,and cost effectiveness,lithium-sulfur(Li-S)batteries are considered as one of the most promising next-generation electrochemical storage systems.However,the notorious polysulfide shuttle effect,which results in low active material utilization and serious capacity fading,severely impedes the practical application of Li-S batteries.Utilizing various electrocatalysts to improve the polysulfide redox kinetics has recently emerged as a promising strategy to address the shuttle effect.Specially,the electronic structure of the electrocatalysts plays a decisive role in determining the catalytic activity to facilitate the polysulfide conversion.Therefore,reasonably modulating the electronic structure of electrocatalysts is of paramount significance for improving the electrochemical performance of Li-S batteries.Herein,a comprehensive overview of the fascinating strategies to tailor the electronic structure of electrocatalysts for Li-S batteries is presented,including but not limited to vacancy engineering,heteroatom doping,single atom doping,band regulation,alloying,and heterostructure engineering.The future perspectives and challenges are also proposed for designing high-efficient electrocatalysts to construct high-energy-density and long-lifetime Li-S batteries.

Luminescence properties of red-emitting Ca_2Al_2SiO_7:Eu^(3+) nanoparticles prepared by sol-gel method

A series of red-emitting Ca2_xA12SiOT：xEu^3＋ （x = 1 mol.%-10 tool.%） phosphors were synthesized by the sol-gel method. The effects of annealing temperature and doping concentration on the crystal structure and luminescence properties of Ca2A12SiO7：Eu^3＋ phosphors were investigated. X-ray diffraction （XRD） profiles showed that all peaks could be attributed to the tetragonal Ca2A12SiO7 phase when the sample was annealed at 1000℃. Scanning electron microscopy （SEM） micrographs indicate that the phosphors have an irregularly rounded mor- phology with particles of about 200 nm. Excitation spectra showed that the strong broad band at around 258 nm and weak sharp lines in 350-490 nm were attributed to the charge transfer band of Eu^3＋-O^2- and f-f transitions within the 4f^6 configuration of Eu^3＋ ions, respectively. Emission spectra implied that the red luminescence could be attributed to the transitions from the ^5D0 excited level to the 7Fj （J = 0, 1, 2, 3, 4） levels of Eu3＋ions with the main electric dipole transition ^5D0→^7F2 （618 and 620 nm）, and Eu^3＋ ions prefer to occupy a lower symmetry site in the crystal lattice. Moreover, the photoluminescence （PL） intensity was strongly dependent on both the sintering temperature and doping concentration, and the highest PL intensity was observed at an Eu^3＋ concentration x = 7 mol.% after annealing at ll00℃. The obtained Ca2A12SiO7：Eu^＋3＋ phosphor may have potential application for the red lamp phosphor.

Effect of Ce-base mischmetal addition on the microstructure and mechanical properties of hot-rolled ZK60 alloy

Mg-Zn-Zr(ZK)alloys exhibit notably high mechanical strength amongst all magnesium alloy grades.However,due to the formation of low melting point Mg_3Zn_7-precipitates,these alloys are susceptible to hot cracking,thus compromising their metallurgical processing.The addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds,speed up dynamic recrystallization,refine grain size,enhance corrosion resistance and extend the service temperature due to improved creep resistance.This work deals with the effect of Ce-base mischmetal addition on the hot rolling behaviour of as-cast ZK60 alloy.The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg_(7)Zn_(3) intermetallics occur during hot rolling,whereas no further precipitation is observed for the ZK60-Mm alloys.The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg_(7)Zn_(3) are observed for the ZK60,whereas Mg_(7)Zn_(3) and Mg Zn_(2) Ce intermetallics are formed in the alloy modified with mischmetal addition.A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the ZK60.Continuous recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates.The mechanical strength and,in particular,the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast condition.The mechanical strength is,however,higher for the ZK60 alloy.Less solid solution strengthening,softer Mg Zn_(2) Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of ZK60-Mm.Failure in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.

Boosting polysulfide redox conversion of Li-S batteries by one-step-synthesized Co-Mo bimetallic nitride

Lithium-sulfur(Li-S)batteries are considered as one of the most promising next generation energy storage systems due to the high theoretical specific capacity,low cost,and environmental benignity.However,the notorious shuttle effect of polysulfides hinders the practical application of Li-S batteries.Herein,we have rationally designed and synthesized sea urchin-like Co-Mo bimetallic nitride(Co_(3) MO_(3) N)in the absence of additional nitrogen sources with only one step,which was applied as the sulfur host materials for Li-S batteries.The results indicate that Co_(3) Mo_(3) N can efficiently anchor and catalyze the conversion of polysulfides,thus accelerating the electrochemical reaction kinetics and enabling prominent electrochemical properties.As a consequence,the S@Co_(3) Mo_(3) N cathode exhibits a high rate performance of 705 mAh g^(-1) at 3 C rate and an excellent cycling stability with a low capacity fading rate of 0.08%per cycle at 1 C over 600 cycles.Even at a high sulfur loading of 5.4 cmg cm^(-2),it delivers a high initial areal capacity of 4.50 mAh cm^(-2) which is still retained at 3.64 mAh cm^(-2) after 120 cycles.Furthermore,the catalytic mechanism and structural stability of Co_(3) Mo_(3) N during cycling were elucidated by a combination of X-ray photoelectron spectroscopy and X-ray absorption fine structure.This work highlights the strategy of structure-catalysis engineering of bimetallic nitride,which is expected to have a wide application in Li-S batteries.

Carbon dots regulate the interface electron transfer and catalytic kinetics of Pt-based alloys catalyst for highly efficient hydrogen oxidation

The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.

Effects of Size and Surface Modification of Multi-walled Carbon Nanotubes on Mechanical Properties of Polyurethane-based Nanocomposites

Polyurethanes/multi-walled carbon nanotube （PU/CNT） composites were prepared with a help of ultrasonically dispersing CNT in the traditional procedure of synthesizing polyurethane. In this case, the various loading levels, sizes and surface-modified groups were considered to regulate the mechanical performances of the PU/CNT nanocomposites. Moreover, the structure and mechanical properties of all the PU/CNT nanocomposites were investigated by attenuated total reflection-Fourier transform infrared spectroscopy, dynamic mechanical analysis, scanning electron microscope, transmission electron microscope, and tensile testing. The experimental results showed that a moderate loading-level of 0.1wt% and a diameter of 10-15 nm for CNT could produce the maximum tensile strength and elongation while it was worth noting that the surface carboxylation of CNT could further enhance the tensile strength and elongation of the PU/CNT nanocomposites.

Integrated Photothermal Nanoreactors for Effi cient Hydrogenation of CO_(2)

To alleviate the energy crisis and global warming,photothermal catalysis is an attractive way to effi ciently convert CO_(2)and renewable H_(2) into value-added fuels and chemicals.However,the catalytic performance is usually restricted by the trade-off between the dispersity and light absorption property of metal catalysts.Here we demonstrate a simple SiO 2-protected metal-organic framework pyrolysis strategy to fabricate a new type of integrated photothermal nanoreactor with a comparatively high metal loading,dispersity,and stability.The core-satellite structured Co@SiO_(2)exhibits strong sunlight-absorptive abil-ity and excellent catalytic activity in CO_(2)hydrogenation,which is ascribed to the functional separation of diff erent sizes of Co nanoparticles.Large-sized plasmonic Co nanoparticles are mainly responsible for the light absorption and conversion to heat(nanoheaters),whereas small-sized Co nanoparticles with high intrinsic activities are responsible for the catalysis(nanoreactors).This study provides a new concept for designing effi cient photothermal catalytic materials.

Recent Progress of Metal Organic Frameworks-Based Electrocatalysts for Hydrogen Evolution,Oxygen Evolution,and Oxygen Reduction Reaction

Exploring efficient and cost-saving electrocatalysts is essential to the renewable energy storage and utilization,which is still in its embryonic period.MOFs have drawn tremendous attention due to their adjustability,abundant active sites,and plentiful pores.Notably,satisfactory electrocatalytic performance has been achieved by MOFs-based electrocatalysts comparable to traditional electrocatalysts.State-of-the-art works about the MOFs-based electrocatalysts for hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and ORR were summarized in this review.This review comprises a series of modifying strategies of MOFs and their derivatives,from aspects of structure,composition,and morphology.Furthermore,the active sites and functional mechanisms’recognition are involved in this review expecting to provide reference for rationally designing efficient electrocatalysts.At last,the current status,challenges,and perspectives of MOFs-based electrocatalysts are also discussed.

Preparation and Characterization of Dichlorocarbene Modified Multiple-walled Carbon Nanotubes

Multiple-walled carbon nanotubes were functionalized by cycloaddition of dichlorocarbene.The chemical modification was performed by using chloroform and sodium hydroxide.Various phase transfer catalysts were used to increase the efficiency of the reaction.Benzyltriethylammonium chloride used as phase transfer catalyst could highly enhance the effect of functionalization.Elemental analysis was used to evaluate the degree of functionalization.Characterization was performed using scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.Fourier transform infrared spectroscopy（FTIR）and energy-dispersive X-ray spectroscopy（EDS）were used to confirm the resulting material.