Stabilizing perovskite precursors with the reductive natural amino acid for printable mesoscopic perovskite solar cells

Solution processability significantly advances the development of highly-efficient perovskite solar cells.However,the precursor solution tends to undergo irreversible degradation reactions,impairing the device performance and reproducibility.Here,we utilize a reductive natural amino acid,Nacetylcysteine(NALC),to stabilize the precursor solution for printable carbon-based hole-conductorfree mesoscopic perovskite solar cells.We find that I_(2) can be generated in the aged solution containing methylammonium iodide(MI) in an inert atmosphere and speed up the MA-FA^(+)(formamidinium) reaction which produces large-size cations and hinders the formation of perovskite phase.NALC effectively stabilizes the precursor via its sulfhydryl group which reduces I_(2) back to I^(-)and provides H^(+).The NALC-stabilized precursor which is aged for 1440 h leads to devices with a power conversion efficiency equivalent to 98% of that for devices prepared with the fresh precursor.Furthermore,NALC improves the device power conversion efficiency from 16.16% to 18.41% along with enhanced stability under atmospheric conditions by modifying grain boundaries in perovskite films and reducing associated defects.

Preparation of hierarchical mesoporous Zn/HZSM-5 catalyst and its application in MTG reaction

The hierarchical mesoporous Zn/ZSM-5 zeolite catalyst was prepared by NaOH treatment and Zn impregnation, and its application in the conversion of methanol to gasoline （MTG） was studied. N2 adsorption-desorption results showed that the mesopores with sizes of 2-20 nm in HZ5/0.3AT was formed by 0.3 M NaOH alkali treatment. The zeolite samples after modification were also characterized by XRF, AAS, XRD, SEM and NH3-TPD methods. Zn impregnated catalyst Zn/HZ5/0.3AT exhibited dramatic improvements in catalytic lifetime and liquid hydrocarbons yield. The selectivity of aromatic hydrocarbons was also improved after Zn impregnation. It is suggested that the mesopores of Zn/HZ5/0.3AT enhanced the synergetic effect of Zn species and acid sites and the capability to coke tolerance, which were confirmed by the results of catalytic test and TGA analysis, respectively.

Recent Progress on Spectroscopy of Lanthanide Ions Incorporated in Semiconductor Nanocrystals

Doping luminescent lanthanide ions into semiconductor nanocrystals is an ideal approach for developing nanodevices for various applications. Quantum confinement effects are expected for lanthanide ions doped in small semiconductor nanocrystals. The most recent progress on the synthesis and spectroscopy of lanthanide ions in various semiconductor nanocrystals such as Ⅱ -Ⅵ, Ⅲ-Ⅴ and Ⅳ-Ⅵ families were systematically reviewed, focusing on our recent findings on the optical spectroscopy of Eu^3 ＋ doped in ZnO and TiO2 nanocrystals by wet chemical synthesis. The energy transfer from the band-gap excitation to lanthanides further confirmed that lanthanide ions could be successfully incorporated into the lattice sites in spite of the mismatch in ionic radii.

Crystal Growth Kinetics of Nanocrystalline ZnS under Surface Adsorption

The crystal growth mechanism, kinetics, and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study, by introducing the strong surface adsorption of the concentrated NaOH, two-stage crystal growth kinetics of ZnS nanoparficles was observed. In the first stage, the primary particles grow into a size over a hundred times of the original volume and the growth is controlled by the crystallographically specific oriented attachment. The first stage data were fitted by the ＂multistep OA kinetic model＂ built based on the molecular collision and reaction. In the second stage, following the dispersal of nanoparficles, an abrupt transition from asymptotic to parabola growth kinetics occurs, which can be fitted by a standard Ostwald ripening volume diffusion model. The presence of surface adsorption causes the two-stage growth kinetics and permits an almost exclusive OA-based growth to dominate in the first stage.

Green synthesis of multifunctional carbon dots for anti-cancer and anti-fungal applications

Carbon dots(CDs)have become popular nanomaterials in biomedical and agricultural fields.Herein we synthesized multifunctional CDs which showed anti-cancer and anti-fungal activities.The low cytotoxicity,stable fluorescence and high photothermal conversion efficiency enable the CDs with imagingguided photothermal therapy.The CDs also exhibited intrinsic anti-fungal activity even at a low concentration,i.e.,40 mg·L^(-1) of CDs induced 20%mortality in cucumber downy mildew.Moreover,the largeπ-conjugated nanostructure and the richness of amino and hydroxyl groups make them a powerful delivery platform for flumorph(a fungicide)with a high loading efficiency of 47.18%.Meanwhile,the heat converted from the light can accelerate the release of flumorph from CDs,and thus efficiently kill fungus.

Inhibition Effects of Pyrazine and Piperazine on the Corrosion of Mg-10Gd-3Y-0.5Zr Alloy in an Ethylene Glycol Solution

The corrosion and inhibition effect of magnesium-based rare-earth containing alloy Mg-10Gd-3Y-0.5Zr (GW103) was studied in an ethylene glycol (EG) solution mixed with organic inhibitors. The inhibition efficiencies of piperazine and pyrazine inhibitors on the corrosion of GW103 were compared by means of potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) and weight loss measurements. It was found that the corrosion process of GW103 alloy in EG solution was hindered by these two inhibitors and the inhibition of pyrazine was more effective than that of piperazine. It was implied that pyrazine could be an effective inhibitor for GW103 in an ethylene glycol coolant solution.

Effect of surface treatment on rheological behaviors of glass bead/hydroxyl terminated polybutadiene suspensions

Surface treatment of glass bead(GB) was carried out by using γ-glycidoxypropyltrimethoxy silane(GPTES) and γ-methacryloxypropyltrimethoxy silane(MPTMS) as coupling agents,respectively.The steady viscosity and yield stress of the GB/hydroxyl terminated polybutadiene(HTPB) suspensions were determined by Brookfield R/S rheometer.The effect of surface treatment on the viscosity and yield stress of GB/HTPB suspension was investigated.The results indicate that the viscosity of the pristine GB/HTPB suspension increases with increasing GB,and the relationship between its viscosity and volume fraction of GB depends on the shear rate.The modification of GB by MPTMS changes the viscosity of the MPTMS@GB/HTPB suspension,and its viscosity is the minimum at the MPTMS dosage of 0.3 g per 1 g GB.Additionally,the modification of GB by MPTMS increases the yield stress of the GB/HTPB suspension,and its yield stress is the maximum at the MPTMS dosage of 0.1 g per 1 g GB.The GPTES modified GB/HTPB suspension behaves lower viscosity and weaker shear thinning than the MPTMS modified GB/HTPB suspension within the range of experimental shear rate.

Studies on the Properties of ZnO Crystal Plane Grown by the Innovated Hydrothermal Method

ZnO single crystals were grown by the innovated hydrothermal method. The crystal surfaces were polished, and then studied by atom force microscope （AFM） and wet-chemical etching （WCE）. It was found that the Zn polar plane was smoother than O polar plane under the same polishing conditions. The etch pit density of Zn polar plane is 4.3×10^3 cm^-2, which is consistent with the previous report, while the density of etch pit of O polar plane is more than 103cm^-2. After annealing treatment, the density of etch pit of Zn plane reduces to 5.8×102 cm^2 and is superior to the current report. This investigation reveals that the high quality ZnO single crystals with fine Zn polar plane can be obtained by the innovated hydrothermal method.

Unveiling the effect of amino acids on the crystallization pathways of methylammonium lead iodide perovskites

Multifunctional additives are widely used to improve crystallization and to passivate defects in perovskite solar cells. The roles of these additives are usually related to the various functional groups contained in such additives. Here, we introduce a serious of analogues of amino acids into methylammonium lead iodide perovskites and find they play different roles in the crystallization process despite the fact that these additives share exactly the same terminal groups, namely one amino group and one carboxyl group. The corresponding crystallization pathways are established for the first time via monitoring the time-resolved phase formation and transformation. We find that avoiding the rapid formation of perovskites from precursor solution can facilitate the uniform nucleation and growth of perovskite crystals with enhanced crystallinity and reduced defects. Further, we find the different crystallization behaviors probably arise from the inherent structural characteristic of these additives, leading to different interactions in the precursors. This study unveils the effects of amino acids on the liquid–solid crystallization process and helps better understand the role of multifunctional additives beyond their functional groups.

Unveiling the Underlying Mechanism of Transition Metal Atoms Anchored Square Tetracyanoquinodimethane Monolayers as Electrocatalysts for N_(2) Fixation

We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(labeled as:TM-sTCNQ,TM=3d,4d,5d series transition metals)by employing density functional theory method.Through highthroughput screenings and full reaction path researches,two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and MosTCNQ have been obtained.The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as−0.48 V.Furthermore,the Nb-sTCNQ catalyst can quickly desorb NH3 produced with a free energy of 0.65 eV,giving Nb-sTCNQ excellent catalytic cycle performance.The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N_(2),which enables the active center to adsorb and activate inert N_(2) molecules well,and the reduction processes require small energy input(i.e.,the maximum free energy changes are small).This work provides insights for finding highly efficient,stable,and low-cost nitrogen reduction reaction electrocatalysts.We hope our results can promote further experimental and theoretical research of this field.

Structural and Thermomechanical Study of Plastic Films Made from Cassava-Starch Reinforced with Kaolin and Metakaolin

The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young’s modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700°C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young’s modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90°C to 120°C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.

Two-Dimensional Organometallic TM3–C12S12 Monolayers for Electrocatalytic Reduction of CO2

Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investigate the electrocatalytic performance of the first transition metal series TM3–C12S12 monolayers on CO2 using spin-polarized density functional theory.The calculations show that M3–C12S12 exhibits excellent catalytic activity and selectivity in the catalytic reduction in CO2.The main reduction products of Sc,Ti,and Cr are CH4.V,Mn,Fe and Zn mainly produce HCOOH,and Co produces HCHO,while CO is the main product for Ni and Cu.For Sc,Ti,and Cr,the overpotentials are>0.7 V,while for V,Mn,Fe,Co,Ni,Cu,Zn,the overpotentials are very low and range from 0.27 to 0.47 V.Therefore,our results indicate that many of the M3–C12S12 monolayers are expected to be excellent and efficient CO2 reduction catalysts.

La/Zn/HZSM-5催化剂上的甲醇芳构化研究(英文)

Aromatization of methanol over co-impregnated La/Zn/HZSM-5 zeolite catalyst was studied.The selectivity of aromatics and BTX(benzene,toluene,and xylene)reached 64.0%and 56.6%,respectively,using La/Zn/HZSM-5 at 437°C,0.1 MPa and methanol WHSV(weight hourly space velocity)=0.8 h-1.Catalytic results showed that the La species was a very good promoter,increased selectivity of aromatics,and prolonged the catalyst lifetime on stream.The effects of the SiO2/Al2O3 ratio in zeolite,Zn and La loading,WHSV,reaction temperature, water content in the feed and H2 pretreatment of catalysts on the catalytic performance were studied in detail. Characterizations of the catalysts by thermogravimetric analysis(TGA),NH3-TPD(temperature programmed desorption),SEM(scanning electron micrograph),N2 adsorption-desorption,XRD(X-ray diffraction)and XRF (X-ray fluorescence),were carried out to understand the structure and discuss the aromatization performance of La/Zn/HZSM-5 zeolite catalyst.

生态友好型缓蚀剂荠菜提取液在1mol·L^(-1)盐酸介质中对Q235碳钢的缓蚀行为研究（英文）

The corrosion inhibition effect of Capsella bursa-pastoris extracts(CBE) for Q235 carbon steels in 1 mol·L-1hydrochloric acid solution was studied using electrochemical methods, environmental scanning electron microscopy(SEM) and Raman microscopy analysis. The polarization plots indicate that CBE serves as an effective, mixedtype inhibitor. Linear polarization resistance shows that increasing CBE concentration and temperature results in increased inhibition ef ficiency. The highest inhibition ef ficiency can reach 97% when adding 60 mg·L-1CBE,which is better than some reported plant extracts under the similar environment. The adsorption of CBE molecules is found to obey the Langmuir adsorption isotherm. Some thermodynamic and kinetic parameters for the adsorption process, such as the adsorption equilibrium constant(K), free energy of adsorption(ΔG ads), activation energy of corrosion reaction(E a) and the heat of adsorption(Q ads), are calculated and discussed. SEM and Raman microscopy analysis also demonstrate the formation of a CBE inhibition film on the metal surface.

Dynamic Mechanical Behavior and Prediction for PP/POE Blends

Polypropylene（PP）/ethylene-octene copolymer（POE） blends were prepared with a twin-screw extruder.Their dynamic mechanical behavior were systematically investigated.The results show that PP/POE blends are heterogeneities with a partial compatible two-phase structure,the glass transition temperature of PP phases in the blends tends to shift towards high temperature with increasing the POE content,and the glass transition temperature of POE phases shifts towards the low temperature with increasing the PP content.The Kerner＇s dispersed phase model and co-continuous phase model can reasonably predict the visco-elasticity of PP/POE blends with different compositions.Additionally,the morphological structure of the blends can be estimated via comparing the predicted DMA behavior with the experimental data.

Spectroscopy and Energy Transfer in Yb^(3+) and Tm^(3+) Co-doped Gd_3Ga_5O_(12) Crystal

Yb3＋/Tm3＋ co-doped Gd3Ga5O12 single crystal with a dimension of Φ30mm×20mm was grown successfully by Czochralski method.The absorption spectrum was recorded at room temperature and used to calculate the absorption cross-section.Based on the Judd-Ofelt（J-O） theory,we obtained the three intensity parameters and spectral parameters of this crystal,such as the line strengths,oscillator strengths,radiative probabilities and radiative lifetimes as well as the fluorescent branching ratios.Room temperature fluorescence spectra and luminescence decay curves were recorded.The energy transfer between Yb3＋-Tm3＋ was observed and the mechanism was discussed.The stimulated emission cross-section of the 3F4→3H6 transition was calculated by the Füchtbauer-Ladenburg（F-L） equation.The potential laser gains for this transition were also investigated.This crystal is promising as a tunable infrared laser crystal at 2.0 μm.

Corrosion and fatigue in micro-sized Ni cantilever beams

The Ni microcantilevers were fabricated by femtosecond laser. The corrosion behavior of the micro-sized Ni cantilever beams was studied by electrochemical noise and a newly developed fatigue testing method. The results show that the micro-sized specimens exhibit general corrosion behavior under the studied corrosion condition,whereas the ordinary-sized plates exhibit the localized corrosion behavior. The critical load amplitude of the micro-sized Ni specimens under corrosion fatigue status was determined to be 15 mN. The maximum bending loads,which were measured by fatigue tests,decrease gradually prior to final fracture. Corrosion fracture first occurs in the range of notch with a higher tensile bending stress,and exhibits clear evidence of trans-columnar fracture. The variation of maximum bending loads with time agrees with that creep deformation of the micro-sized Ni specimens can easily occur at room temperature,which implies that the micro-sized Ni specimens appear to have an improved resistance towards total crack as compared with the ordinary-sized Ni specimens.