Assembling ionic liquid into porous molecular filler of mixed matrix membrane to trigger high gas permeability,selectivity,and stability for CO_(2)/CH_(4) separation

As an emerging zero-dimensional nano crystalline porous material,porous organic cages(POCs)with soluble properties in organic solvents,are promising candidates as molecular fillers in mixed matrix membranes(MMMs).The pore structure of POCs should be adjusted to trigger efficient gas separation performance,and the interaction between filler and matrix should be optimized.In this work,ionic liquid(IL)was introduced into the molecular fillers of CC3,to construct the IL@CC3/PIM-1 membrane to effectively separate CO_(2) from CH_(4).The advantages of doping IL include:(1)narrowing the cavity size of POCs from 4.4 to 3.9Åto enhance the diffusion selectivity,(2)strengthening the CO_(2) solubility to heighten the gas permeability,and(3)improving the compatibility between filler and matrix to upgrade membrane stability.After the optimization of the membrane composite,the IL@CC3/PIM-1-10%membrane possesses the CO_(2) permeability of 7868 Barrer and the CO_(2)/CH_(4) selectivity of 73.4,which compared to the CC3/PIM-1-10%membrane,improved by 15.9%and 106.2%,respectively.Furthermore,the membrane has maintained a stable separation performance at varied temperatures and pressures during the long-term test.The proposed method offers an efficient way to improve the performance of POCs-based MMMs in gas separation.

Autocatalytic reduction-assisted synthesis of segmented porous PtTe nanochains for enhancing methanol oxidation reaction

Morphology engineering has been developed as one of the most widely used strategies for improving the performance of electrocatalysts.However,the harsh reaction conditions and cumbersome reaction steps during the nanomaterials synthesis still limit their industrial applications.Herein,one-dimensional(1D)novel-segmented PtTe porous nanochains(PNCs)were successfully synthesized by the template methods assisted by Pt autocatalytic reduction.The PtTe PNCs consist of consecutive mesoporous architectures that provide a large electrochemical surface area(ECSA)and abundant active sites to enhance methanol oxidation reaction(MOR).Furthermore,1D nanostructure as a robust sustaining frame can maintain a high mass/charge transfer rate in a long-term durability test.After 2,000 cyclic voltammetry(CV)cycles,the ECSA value of PtTe PNCs remained as high as 44.47 m^(2)·gPt^(-1),which was much larger than that of commercial Pt/C(3.95 m^(2)·gPt^(-1)).The high catalytic activity and durability of PtTe PNCs are also supported by CO stripping test and density functional theory calculation.This autocatalytic reduction-assisted synthesis provides new insights for designing efficient low-dimensional nanocatalysts.

Expanding the dimensionality of proton conduction enables ultrahigh anhydrous proton conductivity of phosphoric acid-doped covalent-organic frameworks

It is of great significance to develop high-temperature anhydrous proton conducting materials.Herein,we report a new strategy to significantly enhance the proton conductivity of covalent organic frameworks(COFs)through expanding the dimensionality of proton conduction.Three COF-based composites,COF-1@PA,COF-2@PA,and COF-3@PA(PA:phosphoric acid),are prepared by PA doping of three COFs with similar pore sizes but different amounts of hydrophilic groups.With the increase of hydrophilic groups,COFs can load more PA because of the enhanced hydrogen–bonding interactions between PA and the frameworks.powder X-ray diffraction(PXRD),scanning electron microscopy(SEM),and two-dimensional(2D)solid-state nuclear magnetic resonance(NMR)analyses show that PA can not only enter the channels of COF-3,but also insert into its 2D interlayers.This expands the proton conduction pathways from one-dimensional(1D)to three-dimensional(3D),which greatly improves the proton conductivity of COF-3.Meanwhile,the confinement effect of 1D channels and 2D layers of COF-3 also makes the hydrogen-bonded networks more orderly in COF-3@PA-30(30μL of PA loaded on COF-3).At 150℃,COF-3@PA-30 exhibits an ultrahigh anhydrous proton conductivity of 1.4 S·cm−1,which is a record of anhydrous proton conductivity reported to date.This work develops a new strategy for increasing the proton conductivity of 2D COF materials.

Antiferromagnetic element Mn modified PtCo truncated octahedral nanoparticles with enhanced activity and durability for direct methanol fuel cells

Pt-based magnetic nano catalysts are one of the most suitable cand idates for electrocatalytic materials due to their high electrochemistry activity and retrievability.Unfortunately,the inferior durability prevents them from being scaled-up,limiting their commercial applications.Herein,an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles(TONPs)by one-pot method.Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its an tiferromag netism.At low temperatures,Mn-PtCo TONPs are ferromag netic,and the coercivity in creases gradually with in creasi ng Mn contents.At room temperature,the Mn-PtCo TONPs display superparamag netic behavior,which is greatly helpful for in dustrial recycling.Mn doping can not only modify the electronic structure of PtCo TONPs but also enhanee electrocatalytic performance for methanol oxidation reaction.The maximum specific activity of Mn-PtCo-3 reaches 8.1 A`m^-2,3.6 times of commercial Pt/C(2.2 A·m^-2)and 1.4 times of PtCo TONPs(5.6 A`m^-2),respectively.The mass activity decreases by only 30%after 2,000 cycles,while it is 45%and 99%(nearly inactive)for PtCo TONPs and commercial Pt/C catalysts,respectively.

Atomic-scaled surface engineering Ni-Pt nanoalloys towards enhanced catalytic efficiency for methanol oxidation reaction

Surface engineering is known as an effective strategy to enhance the catalytic properties of Pt-based nanomaterials.Herein,we report on surface engineering Ni-Pt nanoalloys with a facile method by varying the Ni doping concentration and oleylamine/oleicacid surfactant-mix.The alloy-composition,exposed facet condition,and surface lattice strain are,thereby manipulated to optimize the catalytic efficiency of such nanoalloys for methanol oxidation reaction(MOR).Exemplary nanoalloys including Ni_(0.69)Pt_(0.31)truncated octahedrons,Ni_(0.45)Pt_(0.55)nanomultipods and Ni_(0.20)Pt_(0.80)nanoflowers are thoroughly characterized,with a commercial Pt/C catalyst as a common benchmark.Their variations in MOR catalytic efficiency are significant:2.2 A/mgPt for Ni_(0.20)Pt_(0.80)nanoflowers,1.2 A/mgPt for Ni_(0.45)Pt_(0.55)nanomultipods,0.7 A/mgPt for Ni_(0.69)Pt_(0.31)truncated octahedrons,and 0.6 A/mgPt for the commercial Pt/C catalysts.Assisted by density functional theory calculations,we correlate these observed catalysis-variations particularly to the intriguing presence of surface interplanar-strains,such as{111}facets with an interplanar-tensile-strain of 2.6%and{200}facets with an interplanar-tensile-strain of 3.5%,on the Ni_(0.20)Pt_(0.80)nanoflowers.

Enhanced photoresponse of Ti0_(2)/MoS_(2)heterostructure phototransistors by the coupling of interface charge transfer and photogating

Two-dimensional(2D)MoS_(2)with appealing physical properties is a promising candidate for next-generation electronic and optoelectronic devices,where the ultrathin MoS_(2)is usually laid on or gated by a dielectric oxide layer.The oxide/MoS_(2)interfaces widely existing in these devices have significant impacts on the carrier transport of the MoS_(2)channel by diverse interface interactions.Artificial design of the oxide/MoS_(2)interfaces would provide an effective way to break through the performance limit of the 2D devices but has yet been well explored.Here,we report a high-performance MoS_(2)-based phototransistor with an enhanced photoresponse by interfacing few-layer MoS_(2)with an ultrathin Ti0_(2)layer.The Ti0_(2)is deposited on MoS_(2)through the oxidation of an e-beam-evaporated ultrathin Ti layer.Upon a visible-light illumination,the fabricated Ti0_(2)/MoS_(2)phototransistor exhibits a responsivity of up to 2,199 A/W at a gate voltage of 60 V and a detectivity of up to 1.67×10^(13)Jones at a zero-gate voltage under a power density of 23.2μW/mm^(2).These values are 4.0 and 4.2 times those of the pure MoS_(2)phototransistor.The significantly enhanced photoresponse of Ti0_(2)/MoS_(2)device can be attributed to both interface charge transfer and photogating effects.Our results not only provide valuable insights into the interactions at Ti0_(2)/MoS_(2)interface,but also may inspire new approach to develop other novel optoelectronic devices based on 2D layered materials.

Controlled fabrication, lasing behavior and excitonic recombination dynamics in single crystal CH3NH3PbBr3 perovskite cuboids

As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices.

Preface

The development of nanotechnology has been considered as one of the most critical advances in the 21st century,because it allows us to create and manipulate nanomaterials and nanodevices in a controllable way.So far,the development of nanotechnology has focused on application-oriented research,the transfer of knowledge from research

Valuation of correlation options under a stochastic interest rate model with regime switching

我们考虑一种关联选择的估价，一种欧洲电话选择的二因素的类似物，在有政体切换的一个壳白人利率模型下面。更明确地，模型参数被看得见的、连续时间的、有限状态的 Markov 链调制。我们由采用措施变化和反的 Fourier 变换的技术为关联选择获得一个不可分的定价公式。经由快 Fourier 变换，数字分析被提供说明我们的模型的实际实现。

Two-dimensional cobalt metal-organic frameworks for efficient C_3H_6/CH_4 and C_3H_8/CH_4 hydrocarbon separation

A Co-based two-dimensional（2 D） microporous metal-organic frameworks, [Co2（TMTA）（DMF）2（H2O）2]·NO3-·DMF（UPC-32） has been synthesized based on 4,4’,4’’-（2,4,6-trimethylbenzene-1,3,5-triyl）tribenzoic acid（H3TMTA）. UPC-32 features a 2 D microporous framework exhibits high adsorption of H2（118.2 cm3/g, 1.05 wt%, at 77 K）, and adsorption heat（Qst） of CO2（34–46 k J/mol）. UPC-32 with narrow distance between layers（3.8 ？） exhibits high selectivity of C3H6/CH4（31.46） and C3H8/CH4（28.04） at298 K and 1 bar. It is the first 2 D Co-MOF that showed selective separation of C3 hydrocarbon from CH4.

Carbon-Involved Near-Surface Evolution of Cobalt Nanocatalysts:An in Situ Study

When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature,the diffusion of carbon on or in catalysts dramatically influences the catalytic performance.Acquiring information on the carbon-diffusioninvolved evolution of catalysts at the atomic level is crucial for understanding the reaction mechanism yet also challenging.For the chemical vapor deposition process of single-walled carbon nanotubes(SWCNTs),we recorded in situ the catalyst state(solid and molten)composition as well as near-surface structural and chemical evolution at the cobalt catalyst-tube interface with carbon permeation using aberration-corrected environmental transmission electron microscopy and synchrotron X-ray absorption spectroscopy.The nucleation of SWCNTs was linked with an alternating dissolving and precipitating cycle of carbon in catalysts close to the nucleation site.Understanding the dynamics of carbon atoms in catalysts brings deeper insight into the growth mechanism of SWCNTs and facilitates inferring mechanisms of other reactions.The methodologies developed here will find broad applications in studying catalytic and other processes.

Layer-controlled Pt-Ni porous nanobowls with enhanced electrocatalytic performance

Hollow and porous Pt-based nanomaterials are promising catalysts with applications in many sustainable energy technologies such as fuel cells. Economical and green synthetic routes are highly desirable. Here, we report a facile approach to prepare double- and single-layered Pt-Ni nanobowls （DLNBs and SLNBs） with porous shells. Microstructural analysis revealed that the shells were constructed of alloyed Pt-Ni nanocrystals and small amounts of Ni compounds. X-ray photoelectron spectra showed that their Pt 4f binding energies shifted in the negative direction compared to those of the commercial Pt/C catalyst. Furthermore, the DLNBs contained greater contents of oxidized Ni species than the SLNBs. The layer-controlled growth processes were confirmed by microscopy, and a formation mechanism was proposed based on the assistance of citrate and poly（vinylpyrrolidone） （PVP）. For the methanol oxidation reaction, the DLNBs and SLNBs exhibited 2.9 and 2.5 times higher mass activities than that of the commercial Pt/C catalyst, respectively. The activity enhancements were attributed to electronic effects and a bifunctional mechanism. Chronoamperometry and prolonged cyclic voltammetry indicated that the Pt-Ni bowl-like structures had better electrochemical properties and structural stability than the commercial Pt/C catalyst, thus making the Pt-Ni nanobowls excellent electrocatalysts for use in direct methanol fuel cells.

Modulating reaction pathways of formic acid oxidation for optimized electrocatalytic performance of PtAu/CoNC

Formic acid oxidation(FAO)is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways.Herein,PtAu bimetallic nanoparticles loaded onto Co and N co-doping carbon nanoframes(CoNC NFs)were designed to improve the selectivity of the direct reaction pathway for efficient FAO.Based on these subtle nanomaterials,the influences of elemental composition and carbon-support materials on the two pathways of FAO were investigated in detail.The results of fuel cell tests verified that the appropriate amount of Au in PtAu/CoNC can promote a direct reaction pathway for FAO,which is crucial for enhancing the oxidation efficiency of formic acid.In particular,the obtained PtAu/CoNC with an optimal Pt/Au atomic ratio of 1:1(PtAu/CoNC-3)manifests the best catalytic performance among the analogous obtained Pt-based electrocatalysts.The FAO mass activity of the PtAu/CoNC-3 sample reached 0.88 A·mg_(Pt)^(-1),which is 26.0 times higher than that of Pt/C.The results of first-principles calculation and CO stripping jointly demonstrate that the CO adsorption of PtAu/CoNC is considerably lower than that of Pt/CoNC and PtAu/C,which indicates that the synergistic effect of Pt,Au,and CoNC NFs is critical for the resistance of Pt to CO poisoning.This work is of great significance for a deeper understanding of the oxidation mechanism of formic acid and provides a feasible and promising strategy for enhancing the catalytic performance of the catalyst by improving the direct reaction pathway for FAO.

Interface structure and strain controlled Pt nanocrystals grown at side facet of MoS_(2)with critical size

The heterostructure of transition metal nanocrystal on two-dimensional(2D)materials exhibits unique physical and chemical properties through various interfacial interactions.It has been established that the atomic structure and strain in the vicinity of the interface determine the band structure and phonon modes of the nanocrystal,regulating the optical and electrical properties of such heterostructures.Hence,metal–support interfacial engineering is a demonstrated approach to acquiring desired properties of the nanocrystals.However,a fundamental understanding of the interfacial structures remains elusive and precise control of the interactions has yet achieved.Herein,we explore the regulation of interface on MoS_(2)supported Pt nanocrystals which were prepared by reducing ultrasonic dispersed potassium chloroplatinate.The Pt-MoS_(2)heterostructure interface was systematically studied by aberration corrected transmission electron microscopy.Three types of Pt-MoS_(2)interfaces with distinct atomic configurations were identified.The strain within the Pt nanocrystals is sensitive to the atomic configuration of the supporting MoS_(2),which regulates the size of the Pt nanocrystals.These results provide insights on tuning of nanocrystal strain,paving the way for precise control of 2D semiconductor heterostructures.

Optimal mean-variance reinsurance and investment strategy with constraints in a non-Markovian regime-switching model

This paper is devoted to study the proportional reinsurance/new business and investment problem under the mean-variance criterion in a continuous-time setting.The strategies are constrained in the non-negative cone and all coefficients in the model except the interest rate are stochastic processes adapted the filtration generated by a Markov chain.With the help of a backward stochastic differential equation driven by the Markov chain,we obtain the optimal strategy and optimal cost explicitly under this non-Markovian regime-switching model.The cases with one risky asset and Markov regime-switching model are considered as special cases.

Erratum to:Interface structure and strain controlled Pt nanocrystals grown at side facet of MoS_(2)with critical size

Erratum to Nano Research 2022,15(9):8493–8501 https://doi.org/10.1007/s12274-022-4449-5 The name of the first author in original paper was unfortunately misspelled.It should be“Yuchen Zhu”,instead of“Yucheng Zhu”.

Ultrahigh Hydrogen Uptake in an Interpenetrated Zn_(4)O-Based Metal–Organic Framework

As a highly promising candidate for hydrogen storage,crucial to vehicles powered by fuel cells,metal–organic frameworks(MOFs)have attracted the attention of chemists in recent decades.H_(2) uptake in an MOF is influenced by many factors such as pore size,ligand functionalization,and open metal sites.The synergistic effect of these factors can significantly enhance the H_(2) uptake in an MOF.Herein,we report a twofold interpenetrated MOF(UPC-501)based on a Zn_(4)O(COO)_(6)secondary building unit with the H_(2) uptake of 14.8 mmol g^(−1)(2.96 wt%)at 77 K and 0.1 MPa.This uptake is the highest among all the reported porous Zn-based MOF materials.Both experimental and theoretical results confirm that the reduced pore size derived from twofold interpenetration and the imidazole-functionalized ligand are responsible for the extremely high H_(2) uptake of UPC-501.