Ratiometric Nanoparticle Probe Based on FRET‐Amplified Phosphorescence for Oxygen Sensing with Minimal Phototoxicity

Luminescent oxygen probes enable direct imaging of hypoxic conditions in cells and tissues, which are associated with a variety of diseases, including cancer. Here, a nanoparticle probe that addresses key challenges in the field is developed, it: i) strongly amplifies room temperature phosphorescence of encapsulated oxygen‐sensitive dyes; ii) provides ratiometric response to oxygen; and iii) solves the fundamental problem of phototoxicity of phosphorescent sensors. The nanoprobe is based on 40 nm polymeric nanoparticles, encapsulating ≈2000 blue‐emitting cyanine dyes with fluorinated tetraphenylborate counterions, which are as bright as 70 quantum dots (QD525). It functions as a light‐harvesting nanoantenna that undergoes efficient Förster resonance energy transfer to ≈20 phosphorescent oxygen‐sensitive platinum octaethylporphyrin (PtOEP) acceptor dyes. The obtained nanoprobe emits stable blue fluorescence and oxygen‐sensitive red phosphorescence, providing ratiometric response to dissolved oxygen. The light harvesting leads to ≈60‐fold phosphorescence amplification and makes the single nanoprobe particle as bright as ≈1200 PtOEP dyes. This high brightness enables oxygen detection at a single‐particle level and in cells at ultra‐low nanoprobe concentration with no sign of phototoxicity, in contrast to PtOEP dye. The developed nanoprobe is successfully applied to the imaging of a microfluidics‐generated oxygen gradient in cancer cells. It constitutes a promising tool for bioimaging of hypoxia.     

Development of Polymeric Nanoprobes with Improved Lifetime Dynamic Range and Stability for Intracellular Oxygen Sensing

A class of core‐shell nanoparticles possessing a layer of biocompatible shell and hydrophobic core with embedded oxygen‐sensitive platinum‐porphyrin (PtTFPP) dyes is developed via a radical‐initiated microemulsion co‐polymerization strategy. The influences of host matrices and the PtTFPP incorporation manner on the photophysical properties and the oxygen‐sensing performance of the nanoparticles are investigated. Self‐loading capability with cells and intracellular‐oxygen‐sensing ability of the as‐prepared nanoparticle probes in the range 0%–20% oxygen concentration are confirmed. Polymeric nanoparticles with optimized formats are characterized by their relatively small diameter (<50 nm), core‐shell structures with biocompatible shells, covalent‐attachment‐imparted leak‐free construction, improved lifetime dynamic range (up to 44 μs), excellent storage stability and photostability, and facile cell uptake. The nanoparticles’ small sensor diameter and core‐shell structure with biocompatible shell make them suitable for intracellular detection applications. For intracellular detection applications, the leak‐free feature of the as‐prepared nanoparticle sensor effectively minimizes potential chemical interferences and cytotoxicity. As a salient feature, improved lifetime dynamic range of the sensor is expected to enable precise oxygen detection and control in specific practical applications in stem‐cell biology and medical research. Such a feature‐packed nanoparticle oxygen sensor may find applications in precise oxygen‐level mapping of living cells and tissue.     

ZnO Nanosheets Abundant in Oxygen Vacancies Derived from Metal‐Organic Frameworks for ppb‐Level Gas Sensing

Surmounting the inhomogeniety issue of gas sensors and realizing their reproducible ppb‐level gas sensing are highly desirable for widespread deployments of sensors to build networks in applications of industrial safety and indoor/outdoor air quality monitoring. Herein, a strategy is proposed to substantially improve the surface homogeneity of sensing materials and gas sensing performance via chip‐level pyrolysis of as‐grown ZIF‐L (ZIF stands for zeolitic imidazolate framework) films to porous and hierarchical zinc oxide (ZnO) nanosheets. A novel approach to generate adjustable oxygen vacancies is demonstrated, through which the electronic structure of sensing materials can be fine‐tuned. Their presence is thoroughly verified by various techniques. The sensing results demonstrate that the resultant oxygen vacancy‐abundant ZnO nanosheets exhibit significantly enhanced sensitivity and shortened response time toward ppb‐level carbon monoxide (CO) and volatile organic compounds encompassing 1,3‐butadiene, toluene, and tetrachloroethylene, which can be ascribed to several reasons including unpaired electrons, consequent bandgap narrowing, increased specific surface area, and hierarchical micro–mesoporous structures. This facile approach sheds light on the rational design of sensing materials via defect engineering, and can facilitate the mass production, commercialization, and large‐scale deployments of sensors with controllable morphology and superior sensing performance targeted for ultratrace gas detection.     

掺镁钛酸锶厚膜氧传感器的敏感机理研究

研究了掺镁钛酸锶（ＳｒＴｉＯ３）厚膜氧传感器的敏感机理，镁在ＳｒＴｉＯ３的含量分别取１０％、２０％、３０％、４０％和５０％（摩尔分数）。实验结果表明，当温度在４００￣９００℃之间、氧分压在３８Ｐａ￣２．６×１０＾４Ｐａ之间时，所有的样品均为空穴导电型（ｐ型）半导体；镁含量为４０％（摩尔分数）的ＳｒＴｉＯ３厚膜样品显示出最好的氧敏性能，在温度为５００￣８００℃时，它对氧分压变化的灵敏度为７￣８．５，     

微型变压吸附制氧与氧疗保健

微型变压吸附制氧具有方便、灵活以及可长期连续供氧等特点,是家庭氧疗保健的最佳供氧方法。随着微型制氧技术的发展,微型变压吸附制氧机的各项性能指标逐步提高。微型变压吸附制氧应用于氧疗保健可以治疗病理性缺氧疾病,可以缓解生理性缺氧症状、环境性缺氧症状。随着人们对氧疗保健认识的深入和供氧设备的发展,氧疗保健将得到快速发展。     

Sodium‐Oxygen Batteries: A Comparative Review from Chemical and Electrochemical Fundamentals to Future Perspective

Alkali metal‐oxygen (Li‐O₂, Na‐O₂) batteries have attracted a great deal of attention recently due to their high theoretical energy densities, comparable to gasoline, making them attractive candidates for application in electrical vehicles. However, the limited cycling life and low energy efficiency (high charging overpotential) of these cells hinder their commercialization. The Li‐O₂ battery system has been extensively studied in this regard during the past decade. Compared to the numerous reports of Li‐O₂ batteries, the research on Na‐O₂ batteries is still in its infancy. Although, Na‐O₂ batteries show a number of attractive properties such as low charging overpotential and high round‐trip energy efficiency, their cycling life is currently limited to a few tens of cycles. Therefore, understanding the chemistry behind Na‐O₂ cells is critical towards enhancing their performance and advancing their development. Chemical and electrochemical reactions of Na‐O₂ batteries are reviewed and compared with those of Li‐O₂ batteries in the present review, as well as recent works on the chemical composition and morphology of the discharge products in these batteries. Furthermore, the determining kinetics factors for controlling the chemical composition of the discharge products in Na‐O₂ cells are discussed and the potential research directions toward improving Na‐O₂ cells are proposed.     

Oxidized Laser‐Induced Graphene for Efficient Oxygen Electrocatalysis

An efficient metal‐free catalyst is presented for oxygen evolution and reduction based on oxidized laser‐induced graphene (LIG‐O). The oxidation of LIG by O₂ plasma to form LIG‐O boosts its performance in the oxygen evolution reaction (OER), exhibiting a low onset potential of 260 mV with a low Tafel slope of 49 mV dec^?1, as well as an increased activity for the oxygen reduction reaction. Additionally, LIG‐O shows unexpectedly high activity in catalyzing Li₂O₂ decomposition in Li‐O₂ batteries. The overpotential upon charging is decreased from 1.01 V in LIG to 0.63 V in LIG‐O. The oxygen‐containing groups make essential contributions, not only by providing the active sites, but also by facilitating the adsorption of OER intermediates and lowering the activation energy.     

加强储液直供式机场航空供氧保障系统建设

针对现代战争的特点和目前部队航空供氧保障的现状,分析了储液直供式机场航空供氧保障系统的优势,论述了加强储液直供式机场航空供氧保障系统建设的可行性。     

Self‐Assembled Ruddlesden–Popper/Perovskite Hybrid with Lattice‐Oxygen Activation as a Superior Oxygen Evolution Electrocatalyst

The oxygen evolution reaction (OER) is pivotal in multiple gas‐involved energy conversion technologies, such as water splitting, rechargeable metal–air batteries, and CO₂/N₂ electrolysis. Emerging anion‐redox chemistry provides exciting opportunities for boosting catalytic activity, and thus mastering lattice‐oxygen activation of metal oxides and identifying the origins are crucial for the development of advanced catalysts. Here, a strategy to activate surface lattice‐oxygen sites for OER catalysis via constructing a Ruddlesden–Popper/perovskite hybrid, which is prepared by a facile one‐pot self‐assembly method, is developed. As a proof‐of‐concept, the unique hybrid catalyst (RP/P‐LSCF) consists of a dominated Ruddlesden–Popper phase LaSr₃Co_1.5Fe_1.5O_10‐δ (RP‐LSCF) and second perovskite phase La_0.25Sr_0.75Co_0.5Fe_0.5O_3‐δ (P‐LSCF), displaying exceptional OER activity. The RP/P‐LSCF achieves 10 mA cm^?2 at a low overpotential of only 324 mV in 0.1 m KOH, surpassing the benchmark RuO₂ and various state‐of‐the‐art metal oxides ever reported for OER, while showing significantly higher activity and stability than single RP‐LSCF oxide. The high catalytic performance for RP/P‐LSCF is attributed to the strong metal–oxygen covalency and high oxygen‐ion diffusion rate resulting from the phase mixture, which likely triggers the surface lattice‐oxygen activation to participate in OER. The success of Ruddlesden–Popper/perovskite hybrid construction creates a new direction to design advanced catalysts for various energy applications.     

工业氧及医用氧中痕量乙炔的检测

生产氧气的空分装置中如果乙炔含量超标,极易引发爆炸,须通过定期检测工业氧或医用氧中的乙炔含量进行预防.经过色谱条件优化,用FID检测器与三氧化二铝毛细柱配合,可检测出氧气中痕量级别的乙炔含量.     

Noble‐Metal‐Free Electrocatalysts for Oxygen Evolution

Oxygen evolution reaction (OER) plays a vital role in many energy conversion and storage processes including electrochemical water splitting for the production of hydrogen and carbon dioxide reduction to value‐added chemicals. IrO₂ and RuO₂, known as the state‐of‐the‐art OER electrocatalysts, are severely limited by the high cost and low earth abundance of these noble metals. Developing noble‐metal‐free OER electrocatalysts with high performance has been in great demand. In this review, recent advances in the design and synthesis of noble‐metal‐free OER electrocatalysts including Ni, Co, Fe, Mn‐based hydroxides/oxyhydroxides, oxides, chalcogenides, nitrides, phosphides, and metal‐free compounds in alkaline, neutral as well as acidic electrolytes are summarized. Perspectives are also provided on the fabrication, evaluation of OER electrocatalysts and correlations between the structures of the electrocatalysts and their OER activities.     

Pt‐Based Nanocrystal for Electrocatalytic Oxygen Reduction

Currently, Pt‐based electrocatalysts are adopted in the practical proton exchange membrane fuel cell (PEMFC), which converts the energy stored in hydrogen and oxygen into electrical power. However, the broad implementation of the PEMFC, like replacing the internal combustion engine in the present automobile fleet, sets a requirement for less Pt loading compared to current devices. In principle, the requirement needs the Pt‐based catalyst to be more active and stable. Two main strategies, engineering of the electronic (d‐band) structure (including controlling surface facet, tuning surface composition, and engineering surface strain) and optimizing the reactant adsorption sites are discussed and categorized based on the fundamental working principle. In addition, general routes for improving the electrochemical surface area, which improves activity normalized by the unit mass of precious group metal/platinum group metal, and stability of the electrocatalyst are also discussed. Furthermore, the recent progress of full fuel cell tests of novel electrocatalysts is summarized. It is suggested that a better understanding of the reactant/intermediate adsorption, electron transfer, and desorption occurring at the electrolyte–electrode interface is necessary to fully comprehend these electrified surface reactions, and standardized membrane electrode assembly (MEA) testing protocols should be practiced, and data with full parameters detailed, for reliable evaluation of catalyst functions in devices.     

新型氧分离材料YBaCo4O7的氧行为与应用

YBaCo4O7是一种具有奇特氧吸附行为的材料,它在300℃左右的较低温度时就可以吸附其自身质量3%的氧,并且所吸附的氧在400℃可以快速脱附,同时具有稳定的循环特性,是一种非常有潜力的氧分离材料。介绍了YBaCo4O7的晶体结构及在外界温度变化时所产生的独特氧吸附/脱附特性;综述了晶格中不同位置的元素掺杂替代对其氧特性的影响;并对此类材料在透氧膜、脱氧纯化剂等方面的潜在应用进行了初步探索,最后总结了当前存在的一些问题并展望了可能的解决途径。     

Turning Waste into Treasure: Regulating the Oxygen Corrosion on Fe Foam for Efficient Electrocatalysis

Iron corrosion causes a great damage to the economy due to the function attenuation of iron‐based devices. However, the corrosion products can be used as active materials for some electrocatalytic reactions, such as oxygen evolution reaction (OER). Herein, the oxygen corrosion on Fe foams (FF) to synthesize effective self‐supporting electrocatalysts for OER, leading to “turning waste into treasure,” is regulated. A dual chloride aqueous system of “NaCl‐NiCl₂” is employed to tailor the structures and OER properties of corrosion layers. The corrosion behaviors identify that Cl^? anions serve as accelerators for oxygen corrosion, while Ni²⁺ cations guarantee the uniform growth of corrosion layers owing to the appeared chemical plating. The synergistic effect of “NaCl‐NiCl₂” generates one of the highest OER activities that only an overpotential of 212 mV is required to achieve 100 mA cm^?2 in 1.0 m KOH solution. The as‐prepared catalyst also exhibits excellent durability over 168 h (one week) at 100 mA cm^?2 and promising application for overall water splitting. Specially, a large self‐supporting electrode (9 × 10 cm²) is successfully synthesized via this cost‐effective and easily scale‐up approach. By combining with corrosion science, this work provides a significant stepping stone in exploring high‐performance OER electrocatalysts.     

化学链制氧技术铜基氧载体的性能研究

在STA409PC热重分析仪上对Cu/Si氧载体的脱氧-吸氧性能加以研究, 并利用BET、SEM和XRD对所制备氧载体的比表面积、表面形貌和物相组成进行分析。结果表明, 在N₂氛围中, 当温度高于850℃时Cu/Si氧载体脱氧反应进入快速反应阶段; 氧载体在空气氛围中再生的快速反应温度高于400℃; 氧载体脱氧和吸氧的反应速率随颗粒直径的减小及气体流量的增大, 而增大但变化不明显, 而随反应温度的升高, 氧载体脱氧和吸氧反应速率都会急剧增大; 23次循环实验中, 氧载体脱氧-吸氧性能稳定, 经循环之后的氧载体, 颗粒表面变得光滑, 空隙率增加, 但机械强度降低。物相分析结果表明氧载体脱氧后的成分主要有Cu₂O和SiO₂, 吸氧后的成分主要有CuO和SiO₂, 氧载体的制备方法和循环性能有很好的稳定性和适应性。     

微型变压吸附制氧系统(火用)效率与氧气回收率研究

通过改变微型变压吸附制氧系统的均压步骤、吸附温度、氧气流量和设备规模,测得它们对系统火用效率与氧气回收率影响的方向与程度,从而提出提高火用效率和氧气回收率的方向,并找出火用效率和氧气回收率的关系。