氮化碳启发的共价有机框架光催化剂用于高效过氧化氢光合成（英文）

过氧化氢(H₂O₂)是一种绿色高效氧化剂,广泛应用于医药、食品和造纸等领域.传统制备方法为蒽醌氧化法,但该法不仅耗能高,工艺复杂,而且会产生大量废水、废气和固体废物.探索绿色温和条件下新的H₂O₂合成方法成为当前研究热点.其中,以太阳能为驱动力的光催化H₂O₂合成策略广受关注.在光催化反应过程中,半导体光催化剂扮演着至关重要的角色,它们捕获光能、产生光生电荷并引发界面的氧化还原反应.因此,开发高效半导体催化剂是实现高效光催化H₂O₂合成的关键.氮化碳(C₃N₄)是目前应用最为广泛的H₂O₂光合成催化剂.研究表明, C₃N₄中的庚嗪基团能够和活性氧中间体形稳定加成产物,有利于H₂O₂的选择性生成.然而,由于C₃N     

基于Diels-Alder反应的热可逆交联聚醚胺的制备和表征

首先利用聚乙二醇缩水甘油醚(PEG-DE)、乙二醇二缩水甘油醚(EG-DE)与呋喃甲胺(FMA)进行预聚反应,合成了分子链上含有呋喃基团的聚醚胺预聚物(Pre-PEA),然后采用DielsAlder反应,以双马来酰亚胺(BMI)交联该聚醚胺预聚物,制得交联聚醚胺(PEA)。通过拉伸测试系统地分析了PEA的力学性能及其影响因素。结果表明,经过对分子链结构的设计及交联密度的调节,PEA的性能完成了从“软而韧”到“强而韧”的转变。制得的PEA具有很好的自修复性能,表面裂痕可以在120℃以下完全自修复。采用超声重塑法与热压重塑法对制得的PEA进行重塑加工,2次重塑后其断裂强度至少能达到原始样品的70%,断裂伸长率至少能达到原始样品的80%。     

Characteristics and threshold voltage model of GaN-based FinFET with recessed gate

In this work, AlGaN/GaN FinFETs with different fin widths have been successfully fabricated, and the recessed-gate FinFETs are fabricated for comparison. The recessed-gate FinFETs exhibit higher transconductance value and positive shift of threshold voltage. Moreover, with the fin width of the recessed-gate FinFETs increasing, the variations of both threshold voltage and the transconductance increase. Next, transfer characteristics of the recessed-gate FinFETs with different fin widths and recessed-gate depths are simulated by Silvaco software. The relationship between the threshold voltage and the AlGaN layer thickness has been investigated. The simulation results indicate that the slope of threshold voltage variation reduces with the fin width decreasing. Finally, a simplified threshold voltage model for recessed-gate FinFET is established,which agrees with both the experimental results and simulation results.