高居里温度铁电单晶PIN-PT的机电性能

弛豫铁电单晶Pb(In_1/2Nb_1/2)O₃-PbTiO₃(PIN-PT)相较于常用的Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(PMN-PT)具有更高的居里温度,在高稳定性、高性能的传感器、换能器方面具有应用前景。本工作采用谐振法研究了[001]方向极化的0.66PIN-0.34PT铁电单晶的全矩阵机电性能参数。0.66PIN-0.34PT 单晶的三方-四方相变温度(T_RT)约为160 ℃,居里温度(T_C)约为260 ℃,室温压电系数d₃₃、d₃₁、d₁₅分别为1 340 pC/N、-780 pC/N、321 pC/N,介电常数ε^T₃₃、ε^S₃₃、ε^T₁₁、ε^S₁₁分别为2 700、905、2 210、1 927,机电耦合系数 k₃₃、k₃₁、k₁₅、k_t分别为 87%、58%、38%、61%。其纵向压电常数(d₃₃)和纵向机电耦合系数(k₃₃)小于 PMN-PT 单晶,但是横向压电性能(d₃₁)和剪切压电性能(d₁₅)都略高于PMN-PT单晶。另外,研究了机电耦合性能随温度的变化趋势,发现0.66PIN-0.34PT单晶在150 ℃以下有较好的温度稳定性。     

两个基于2,5-二甲氧基对苯二甲酸和咪唑衍生物的超分子钴配位聚合物的结构及光催化反应

本文以咪唑衍生物为配体,通过水热合成法与钴离子制备出两个配位聚合物:{[Co(DTA)(1,4-DIB)(H₂O)]·H₂O}_n(1)和[Co(DTA)(1,3-BMIB)]_n(2)(1,4-DIB=1,4-二(1H-咪唑-1-基)苯; 1,3-BMIB=1,3-二(4-甲基-1H-咪唑-1-基)苯;H₂DTA=2,5-二甲氧基对苯二甲酸)。利用X射线单晶衍射、粉末衍射、热失重、元素分析、红外光谱以及固体紫外-可见光谱等对两个配合物进行了表征。结构分析证实配合物1和2是通过二维结构堆积成的三维超分子化合物。粉末衍射测试则显示两个配合物在水中有很好的稳定性。固体紫外-可见光谱显示两个配合物属半导体材料,对紫外-可见光有很强的吸收作用。在光催化实验中,配合物1和2可加快亚甲基蓝的降解速度。     

MXene-based composite electrodes for efficient electrochemical sensing of glucose by non-enzymatic method

A recently discovered 2D transition titanium metal carbides also called as MXenes (Ti₃C₂T_x)-based nanocomposite was prepared with Cu₂O through wet precipitation technique, and these materials were further developed as the electrode for sensing glucose by chronoamperometry technique. The prepared MXene-Cu₂O (Ti₃C₂T_x-Cu₂O) nanocomposite was characterized by XRD, FTIR, UV–Vis spectroscopy, FE-SEM, EDAX, and Raman spectroscopy. Morphological studies of the composites revealed that the micro-octahedral shape of Cu₂O is distributed on the surface of MXene with size larger than bare Cu₂O. Further, the prepared composite material was fabricated as a sensing probe, and the electrochemical activities were examined by cyclic voltammetric analysis (CV) and chronoamperometric (CA) methods. From the CV and CA investigation, the current response was higher for the composite than the bare material (Cu₂O & MXene) in the presence of glucose. The amperometric investigation of MXene-Cu₂O composite for the detection of glucose shows a broad linear range (0.01–30 mM) with a sensitivity of 11.061/μAmM cm^?2 and a detection limit of 2.83 μM. Further, the fabricated sensor exhibits good selectivity with interfering species like NaCl, fructose, sucrose, urea, ascorbic acid, lactose, short response time, stability, good reproducibility, and compatibility with human serum sample. From the investigation, the prepared MXene-Cu₂O composite is a good candidate for the direct detection of glucose molecules and is also well suitable for clinical diagnosis.     

基于2,5-二溴对苯二甲酸配体的锌/钴配合物合成、晶体结构及性质

将有机物2,5-二溴对苯二甲酸(H₂L₁)和2,2′-联吡啶(L₂)作为双配体,使用溶剂热法和七水合硫酸锌(ZnSO₄·7H₂O)、六水合硝酸钴(Co(NO₃)₂·6H₂O)分别反应,得到配合物[Zn(L₁)(L₂)(H₂O)]_n(1)和配合物[Co(L₁)(L₂)(H₂O)]_n(2)。采用单晶X射线衍射、元素分析、红外光谱、紫外光谱、荧光光谱、热重分析等测试方法对这两种物质进行分析研究。单晶测试结果表明配合物1是单斜晶系,以Zn²⁺配位连接L^2-₁与L₂形成一维链状结构,各条链在分子间氢键和π…π共轭作用下有规律地堆叠形成三维网络结构。配合物2是三斜晶系,Co1离子和Co1ⁱ离子由H₂L₁上的羧酸氧原子O4和O4ⁱ连接,形成双齿螯合的配位结构单元,以Co²⁺配位连接 L^2-₁和L₂形成二维网格结构,各层在O—H…O分子间氢键和范德瓦耳斯力作用下有规律的堆叠形成三维网络结构。配合物1和2均含有芳香杂环、羧基杂环和氮杂环,具有良好的荧光性质和热稳定性,最大发射波长分别为345 nm和333 nm。     

Bicomponent Cocatalyst Decoration on Flux-assisted CaTaO2N Single Crystals for Photocatalytic CO2 Reduction under Visible Light

Cubic-like CaTaO₂N photocatalysts with high crystallinity and uniform particle size were successfully prepared by the flux-assisted nitridation method. The growth of CaTaO₂N single crystals under different synthesis conditions was systematically investigated to understand the effects of the crystallinity and optical property on photocatalytic performance of CO₂ reduction. Moreover, the modification of CaTaO₂N single crystals with core-shell Ni−Ag bicomponent cocatalyst by two-step decoration process gave a 2.4 times higher amount of CO evolution than the deposition of sole Ag cocatalyst, because of the synergistic effects of bicomponent cocatalyst on the interfacial electron transfer and surface catalytic process. This study provides a valuable way to construct high-crystalline photocatalysts with effective bicomponent cocatalyst for visible-light-driven CO₂ reduction with H₂O.     

Modulating Charge Carrier Efficient Separation Enabled by Lewis Base Modification in Paper-based Photoelectrochemical Sensor

The separation efficiency of charge carriers determines the analytical sensitivity of the paper-based photoelectrochemical sensor. Herein, the Lewis base modification strategy is proposed to promote the carrier separation through an in-situ ion exchange method. Firstly, three-dimensional paper-based hierarchically TiO₂ (PHT) arrays are prepared with the one-step hydrothermal method. With the aid of Lewis base, the photo-induced charge separation efficiency and the photocurrent signal are obviously increased. Ultimately, sensitive sensing of prostate specific antigen (PSA) is achieved and the linear range is 1 pg/mL–100 ng/mL with the detection limitation of 0.3 pg/mL.     

Hitherto-Unexplored Photodynamic Therapy of Ag2S and Enhanced Regulation Based on Polydopamine In Vitro and Vivo

Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag₂S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag₂S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag₂S had more opportunities to react with surrounding O₂, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag₂S and PDA-Ag₂S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag₂S showed distinctly better therapeutic effects than Ag₂S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag₂S quantum dots, which extended and enhanced the regulatory effect originating from PDA.     

Heterogeneous copper‐catalyzed oxidative coupling of oxime acetates with sodium sulfinates: An efficient and practical synthesis of β‐keto sulfones

An efficient and practical route to β‐keto sulfones has been developed through heterogeneous oxidative coupling of oxime acetates with sodium sulfinates by using an MCM‐41‐supported Schiff base‐pyridine bidentate copper (II) complex [MCM‐41‐Sb,Py‐Cu (OAc)₂] as the catalyst and oxime acetates as an internal oxidant, followed by hydrolysis. The reaction generates a variety of β‐keto sulfones in good to excellent yields. This new heterogeneous copper (II) catalyst can be easily prepared via a simple procedure from readily available and inexpensive reagents and exhibits the same catalytic activity as Cu (OAc)₂. MCM‐41‐Sb,Py‐Cu (OAc)₂ is also easy to recover and is recyclable up to eight times with almost consistent activity.     

Analysis of F-53B,Gen-X,ADONA, and emerging fluoroalkylether substances in environmental and biomonitoring samples: A review

The persistent, bioaccumulative, and toxic properties of certain per- and polyfluoroalkyl substances (PFAS) raise concerns for environmental and human health. This has led to the gradual phase-out from production and commerce of some legacy PFAS. Fluoroalkylether compounds (ether-PFAS) are among the fluorinated alternative chemicals that are beginning to be reported in impacted and background environments. Extensive monitoring activities were conducted since 2015–2019 to bridge knowledge gaps on the environmental fate and effects of ether-PFAS including F-53B (6:2 chlorinated polyfluoroalkyl ether sulfonate [6:2 Cl-PFAES] and 8:2 Cl-PFAES), Gen-X (hexafluoropropylene oxide dimer acid [HFPO-DA]), and ADONA (dodecafluoro-3H-4,8-dioxanonanoate). In recent years, advances in nontarget screening using high-resolution mass spectrometry have revealed the identities of other infrequently monitored ether-PFAS. In this critical review, we provide an up-to-date inventory of the structures of ether-PFAS discovered in the recent literature. Their environmental occurrence, fate, and effects are discussed on a comparative perspective with some legacy PFAS such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Information on the methods employed for the quantitative and semi-quantitative analysis of ether-PFAS is also provided, including sample preparation and mass spectrometry analysis, analytical performance, and limitations. In particular, the compiled database of MS/MS fragment ions (n = 111) can be useful in spectrum interpretation of novel ether-PFAS. The concluding remarks open on possible research avenues and the challenges that remain to be addressed.