Ion Exchange of Selected Group II Metals and Lead by Crystalline Silicotitanate and Competition for Cs Exchange Sites

ABSTRACT

A series of batch contact tests were conducted to evaluate the exchange behavior of Ba, Ca, Pb, and Sr onto crystalline silicotitanate (CST) in support of an expedited Cs removal and pretreatment system at the Hanford site. Binary Na/M²⁺ and ternary Na/Cs/M²⁺ isotherms were generated to understand selectivity, capacity, and competitive impact of each analyte on Cs uptake from a simple 1 M NaOH/4.6 M NaNO₃ simulant. Analyte loading from a 0.1 M NaOH/5.5 M NaNO₃ simulant was assessed to determine the effect of hydroxide concentration on binary Na/M²⁺ isotherms. Results from binary and ternary isotherms indicated that Group II metals Ca, Sr, and Ba (and Pb) do not impact CST performance toward Cs removal at concentrations expected in Hanford tank-waste supernate.     

Enhanced On–Off Ratio Photodetectors Based on Lead‐Free Cs3Bi2I9 Single Crystal Thin Films

Hybrid organic–inorganic lead halide perovskite single crystal thin film (SCTF) recently has attracted enormous interest in the field of optoelectronic devices, since it efficiently resolves the trade‐off between thickness and carrier diffusion length. However, the toxicity of lead element and the instability induced by organic component still hinder its future developments. In this work, lead‐free all‐inorganic Cs₃Bi₂I₉ SCTF with a high orientation along (00h) has been in situ grown on indium tin oxide (ITO) glass via a space‐limited solvent evaporation crystallization method. The trap density of Cs₃Bi₂I₉ SCTF (5.7 × 10¹² cm^?3) is 263 folds lower than that of the polycrystalline thin film (PCTF) counterpart, together with a 5‐order‐of‐magnitude higher carrier mobility. These superior charge transfer properties enable a photoresponse on–off ratio as high as 11 000, which far surpasses that of the PCTF device by 460 folds, comparable to the lead halide perovskite. Furthermore, the Cs₃Bi₂I₉ SCTF photodetector exhibits outstanding stability even without any encapsulation, whose initial performance is well maintained after aging 1000 h in humid air of 50% RH or continuous on–off light illumination for 20 h. This work will pave the way to produce new families of high‐performance, stable, and nontoxic perovskite SCTF for future optoelectronic applications.     

Novelty All-Inorganic Titanium-Based Halide Perovskite for Highly Efficient Photocatalytic CO2 Conversion

Lead halide perovskite materials have great potential for photocatalytic reaction due to their low fabrication cost, unique optical absorption coefficient, and suitable band structures. However, the main problems are the toxicity and instability of the lead halide perovskite materials. Therefore, a facile synthetic method is used to prepare lead-free environmentally friendly Cs₂TiX₆(X = Cl, Cl_0.5Br_0.5, Br) perovskite materials. Their structural and optical characteristics are systematically investigated. The band gaps of the produced samples are illustrated to be from 1.87 to 2.73 eV. Moreover, these materials can keep high stability in harsh environments such as illumination and heating, and the Cs₂Ti(Cl_0.5Br_0.5)₆ microcrystals demonstrate the yields of 176 µmol g⁻¹ for CO and 78.9 µmol g⁻¹ for CH₄ after light irradiation for 3 h, which is of the first report of Ti-based perovskite photocatalysts. This finding demonstrates that the Ti-based perovskites will create opportunities for photocatalytic applications, which may offer a new idea to construct low-cost, eco-friendly, and bio-friendly photocatalysts.     

Moisture-Induced Reversible Phase Conversion of Cesium Copper Iodine Nanocrystals Enables Advanced Anti-Counterfeiting

Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs₃Cu₂I₅ nanocrystals (NCs) possess excellent hydrochromic properties. The prepared Cs₃Cu₂I₅ NCs films can dynamically extract and insert CsI by exposing/removing water to realize the reversible conversion between blue-emissive Cs₃Cu₂I₅ and yellow-emissive CsCu₂I₃. Interestingly, polymethyl methacrylate (PMMA) coated Cs₃Cu₂I₅ can effectively avoid the extraction of CsI and maintain long-term stability in the water. Further, the hydrochromic Cs₃Cu₂I₅ and water-resistant Cs₃Cu₂I₅@PMMA are used as the inks to synergistically act on anti-counterfeiting information to achieve multiple encryption effects, which can clearly identify and authenticate the effective information after moisture decryption. Importantly, the pattern can be re-encrypted to the invalid pattern after water evaporation. In addition, the anti-counterfeiting pattern has excellent stability during repeated encryption/decryption conversion cycles, which can not only balance the accessibility of anti-counterfeiting information but also effectively improve the security of information. This new discovery may not only deepen the understanding of Cs₃Cu₂I₅ but also provide new options for the design of hydrochromic materials for anti-counterfeiting information.     

Lead-Free Double Perovskite Cs2AgBiBr6: Fundamentals,Applications, and Perspectives

Cs₂AgBiBr₆, as a benchmark lead-free double perovskite, has emerged as a promising alternative to lead-based perovskites because of its high stability, non-toxicity, exceptional optoelectronic properties, and multifunctionality. To encourage further research on Cs₂AgBiBr₆ and its broad applications, in this review, its fundamental properties including the structure-property relation, synthesis, stability, origin of absorption and photoluminescence, electron-phonon coupling, role of defects, charge carrier dynamics, and bandgap modulation are comprehensively emphasized. The recent progress on the wide applications including solar cells, light/X-ray detectors, and ferroelectric/magnetic devices are highlighted. Moreover, the challenges of Cs₂AgBiBr₆ materials and related applications are discussed and perspectives are provided for guiding the future development of this research area.     

有源效率曲线拟合γ谱法快速测定水产品中~(137)Cs

利用~(152)Eu作为刻度源对HPGe-γ谱仪进行效率刻度,拟合出效率曲线,实现对水产品鲜样中~(137)Cs进行快速测量,以满足水产品放射性污染状况评估的需要。研究结果表明,取样品可食部分绞碎后装满2 L马林杯,测量时间6 h的测量结果即可达到0.111 Bq·kg~(-1)鲜样,可以满足针对水产品放射性的食用安全评估的要求。利用此方法对台湾海峡西侧养殖水产品进行检测,部分鱼类中检出~(137)Cs,但含量很低,对人体健康不构成威胁。     

高岭土类粘土矿物材料对模拟核素Sr、Co、Cs的吸附性能研究

对苏州高岭土、北川埃洛石、贵州遵义埃洛石吸附Sr、Co、Cs的性能进行了实验研究,结果表明:①高岭土类粘土矿物对Sr2 、Co2 、Cs2 的吸附能力随着pH值增大而增强,在碱性条件下对Sr2 、Co2 、Cs2 的吸附能力随碱性程度的增加而快速增大;②高岭土类粘土矿物对Sr2 、Co2 、Cs2 的吸附随着吸附剂量的增大,吸附率逐渐增大,单位质量吸附量明显减小;③母液浓度增大,单位质量吸附量增加,吸附率减小;④贵州埃洛石、北川埃洛石对Sr2 、Co2 、Cs2 的吸附性能相近,埃洛石对Sr2 、Co2 、Cs2 的吸附能力好于苏州高岭土。     

气相羟醛缩合法制MA及MMA研究进展

介绍了以丙酸或丙酸酯为原料,用敢相羟醛缩合法制甲基丙烯酸及甲基丙烯酸甲酯的研究进展,催化剂载体,负载离子形式,反应条件等对催化剂性能的影响,以及催化剂再生工艺的研究成果及动态,指出气相羟醛缩合法合成ＭＡ及ＭＭＡ是今后的发展方向。     

上海市2001年～2003年环境水137Cs比活度监测

介绍对上海市2001年～2003年环境水中137Cs比活度进行监测的方法、结果和初步分析.结果表明上海市淡水中137Cs比活度低于1.00×10-4Bq/L,海水中137Cs比活度范围为2.72×10-4～7.47×10-4 Bq/L.     

4C理论在有机化工产品自营贸易中的应用

有机化工产品自营业务是化工销售分公司根据当前市场形势推出的新的业务方式。分析有机化工产品的营销特点。利用4C营销理论指导营销策略的制定,规范自营贸易业务,获取客户的实际需求,根据客户能够接受的最大成本确定价格,为客户提供便利,保证持续、有效的沟通和自营贸易业务的顺利开展。