小型高性能质子转移反应飞行时间质谱仪的研制及其在呼吸气成分分析中的应用

研制可快速、在线分析挥发性有机物（volatile organic compounds, VOCs）的质谱仪器是现代气态有机质谱的重要发展方向。本研究自行研制了小型高性能质子转移反应飞行时间质谱仪（proton transfer reaction time of flight mass spectrometry, PTR-TOF MS）,仪器采用结构简单可靠的空心阴极放电源作为水蒸气电离源,以产生水合质子;线性漂移管作为分子离子反应管。该离子源产生的水合离子纯度高,为水合离子与VOCs的分子离子反应提供可控的反应条件。传输接口部分使用射频四极杆作为离子导向装置,以提高离子传输效率;配合小尺寸飞行时间质量分析器,兼顾仪器的灵敏度与分辨率。质子转移反应的测定原理使该仪器可以分析除少数烷烃外的绝大多数VOCs,同时分析过程不受空气组分的影响。分子离子峰为主的产物离子形式使谱图便于解析,适合高通量分析。测试结果表明,该仪器在m/z 115处全高半峰宽（full width half maximum, FWHM）分辨率优于2 500,对丙酮、苯、甲苯的检出限在6×10^-12~9.6×10^-11 mol/mol之间。将该仪器应用于人体呼吸气的成分分析,取得了良好的结果。     

Laser-Generated Supranano Liquid Metal as Efficient Electron Mediator in Hybrid Perovskite Solar Cells

Creating colloids of liquid metal with tailored dimensions has been of technical significance in nano-electronics while a challenge remains for generating supranano (<10 nm) liquid metal to unravel the mystery of their unconventional functionalities. Present study pioneers the technology of pulsed laser irradiation in liquid from a solid target to liquid, and yields liquid ternary nano-alloys that are laborious to obtain via wet-chemistry synthesis. Herein, the significant role of the supranano liquid metal on mediating the electrons at the grain boundaries of perovskite films, which are of significance to influence the carriers recombination and hysteresis in perovskite solar cells, is revealed. Such embedding of supranano liquid metal in perovskite films leads to a cesium-based ternary perovskite solar cell with stabilized power output of 21.32% at maximum power point tracing. This study can pave a new way of synthesizing multinary supranano alloys for advanced optoelectronic applications.     

Discriminatory Gate-Opening Effect in a Flexible Metal–Organic Framework for Inverse CO2/C2H2 Separation

Considering the significant application of acetylene (C₂H₂) in the manufacturing and petrochemical industries, the selective capture of impurity carbon dioxide (CO₂) is a crucial task and an enduring challenge. Here, a flexible metal–organic framework (Zn-DPNA) accompanied by a conformation change of the Me₂NH₂⁺ ions in the framework is reported. The solvate-free framework provides a stepped adsorption isotherm and large hysteresis for C₂H₂, but type-I adsorption for CO₂. Owing to their uptakes difference before gate-opening pressure, Zn-DPNA demonstrated favorable inverse CO₂/C₂H₂ separation. According to molecular simulation, the higher adsorption enthalpy of CO₂ (43.1 kJ mol⁻¹) is due to strong electrostatic interactions with Me₂NH₂⁺ ions, which lock the hydrogen-bond network and narrow pores. Furthermore, the density contours and electrostatic potential verifies the middle of the cage in the large pore favors C₂H₂ and repels CO₂, leading to the expansion of the narrow pore and further diffusion of C₂H₂. These results provide a new strategy that optimizes the desired dynamic behavior for one-step purification of C₂H₂.     

High-Performance Photocatalytic Reduction of Nitrogen to Ammonia Driven by Oxygen Vacancy and Ferroelectric Polarization Field of SrBi4Ti4O15 Nanosheets

Photo-responsive semiconductors can facilitate nitrogen activation and ammonia production, but the high recombination rate of photogenerated carriers represents a significant barrier. Ferroelectric photocatalysts show great promise in overcoming this challenge. Herein, by adopting a low-temperature hydrothermal procedure with varying concentrations of glyoxal as the reducing agent, oxygen vacancies (Vo) are effectively produced on the surface of ferroelectric SrBi₄Ti₄O₁₅ (SBTO) nanosheets, which leads to a considerable increase in photocatalytic activity toward nitrogen fixation under simulated solar light with an ammonia production rate of 53.41 µmol g⁻¹ h⁻¹, without the need of sacrificial agents or photosensitizers. This is ascribed to oxygen vacancies that markedly enhance the self-polarization and internal electric field of ferroelectric SBTO, and hence, facilitate the separation of photogenerated charge carriers and light trapping as well as N₂ adsorption and activation, as compared to pristine SBTO. Consistent results are obtained in theoretical studies. Results from this study highlight the significance of surface oxygen vacancies in enhancing the performance of photocatalytic nitrogen fixation by ferroelectric catalysts.