Achieving selective oxidation of aromatic alcohols under mild conditions is a major challenge. In this work, selfassembled films were prepared by a step-by-step approach, using meso-tetra（4-carboxyphenyl） porphine or meso-tetra（4-carboxyphenyl） porphine cobalt（II） ligands, zinc inorganic metal node, and 4,4’-bipyridine linker, named TCPP and TCPPCoTCPP, respectively. The preparation process and assembly results of the above self-assembled films were characterized using UV-vis spectroscopy and atomic force microscopy. The results reveal that TCPP-CoTCPP demonstrated higher photogenerated electron-hole（e-h） separation and charge transfer efficiency than TCPP. Under aerobic conditions at room temperature, the TCPP-CoTCPP exhibited excellent simultaneous photocatalytic selective oxidation of aromatic alcohol and H 2 O 2 generation. Under the optimized reaction conditions, the H 2 O 2 evolution of TCPP was 47. 23 mmol, and the selectivity of oxidation of aromatic alcohols to aromatic aldehydes was 48. 4%. By regulating the organic ligand of the self-assembled membrane, the H 2 O 2 evolution of TCPP-CoTCPP was increased to 68. 73 mmol, and the selectivity of oxidation of aromatic alcohol to aromatic aldehyde was improved to 84. 2%.
涂层/基体界面污染率是考核涂层质量的重要指标.针对某新型发动机机匣内壁镍铬涂层界面存在的严重污染问题,首先利用显微组织分析及物相分析手段确定了界面污染物主要成分为Al2O3.然后,进行多因素对比试验重现了界面污染现象,确定了污染物来源为喷砂过程中滞留在基体表面的砂砾,并结合零件尺寸及外形开展了喷砂工艺优化研究.研究结果表明:具有较大动能的砂砾会嵌入硬度较低的基体中,造成界面污染;减少砂粒撞击动能及增加清理时间,可有效地减小涂层/基体界面污染率.
真空气相沉积法具有致密性好、均匀性好、膜厚可控等优点,被认为是一种制备大面积、高质量钙钛矿薄膜的关键技术,在工业化生产上有着巨大的应用潜力.但相较于溶液法,气相沉积存在薄膜晶粒尺寸小,结晶度低等缺点,导致器件光电转换效率较低.采用逐层交替气相沉积法制备钙钛矿薄膜,对碘化铅(PbI2)含量进行调控,使用氯化甲胺和碘化甲铵混合溶液进行表面后处理,钝化了薄膜缺陷,提升了薄膜质量.PbI2 含量的优化调控了钙钛矿薄膜的化学计量比,器件光电性能得到提高.表面后处理引入的氯离子,使钙钛矿晶粒尺寸增大,结晶度提高.器件的短路电流密度明显提升,最终获得17.76％的光电转换效率以及82.1％的填充因子.
In this paper, a low-cost carbon-based sensing slurry was developed using carbon fiber powder（CFP） as a functional filler and ethyl cellulose as an adhesive. The carbon fiber slurry was directly scraped onto the surface of a polyimide film to form a carbon fiber sensing functional layer. Then a simple structured carbon fiber bending sensor was fabricated using copper foil as the electrode. The effect of CFP content on the performance of the bending sensor was explored. The results show that when the carbon fiber content is 0. 02 g·ml -1 , the CFP is completely covered by ethyl cellulose, making it difficult to form a conductive pathway and no bending sensing characteristics. As the carbon fiber content gradually increases, a good conductive pathway is formed inside the CFP membrane, and a large number of holes and even micro-cracks are subsequently produced, which is conducive to the accurate identification of different bending angles and bidirectional identification characteristics of the sensor. The hysteresis and stability of the CFP bending sensor was performed in depth. The best sensing performance of 0. 04 g·ml -1 CFP bending sensor was obtained with less hysteresis, excellent stability and mechanical durability.
Low-doped 4H-SiC epitaxial layers were treated using molten KOH etching and chemical mechanical polishing techniques. The conversion process of basal plane dislocations（BPDs） into threading edge dislocations（TEDs） was optically characterized by confocal laser microscopy and polarizing microscopy. By comparing the slope variations of BPDs and TEDs etch pits, the conversion points were identified and the conversion depths of 15 BPD-TED conversion points were measured.The results show that 93% of conversion occurs in the buffer layer within 1 μm, and only 7% occurs in the drift layer above 1μm, with an average conversion depth of 0. 59 μm. These findings indicate that the conversion of BPDs to TEDs mainly occurs at the interface between the substrate and the epitaxial layer and is completed at the beginning of the epitaxial growth.This study is of great significance for understanding and optimizing SiC crystal epitaxial growth.
