排序方式: 共有130条查询结果,搜索用时 531 毫秒
101.
研究了NH3处理温度对N掺杂P25-TiO2可见光催化活性的影响以及可见光催化活性与表面组成和结构的关系.实验结果表明:NH3处理温度在600℃时,有最高活性;在700℃,P25-TiO2转变为以金红石相为主,表面未发生N掺杂,这与700℃时NH3分解有关;N掺杂浓度、可见光吸收两者与可见光催化活性之间均不存在顺变关系.讨论揭示:N掺杂P25-TiO2的可见光催化活性是由三个要素协同作用产生:(i)表面生成大量束缚单电子氧空位(Vo),(ii)表面有N掺入,(iii)晶型以锐态矿为主,三者缺一不可. 相似文献
102.
本文对TOPCon电池发射结的叠层钝化膜进行了研究,对比了3种不同叠层钝化膜(SiO2/SiNx、Al2O3(1.5 nm)/SiNx、SiO2/Al2O3(1.5 nm)/SiNx)的钝化性能。结果表明:Al2O3(1.5 nm)/SiNx的钝化性能优于SiO2/SiNx,SiO2/Al2O3(1.5 nm)/SiNx的钝化水平最佳,隐开路电压均值可达到705 mV。基于Al2O3/SiNx叠层膜研究了Al2O3厚度(1.5 nm、3 nm和5 nm)对钝化性能和电池转换效率的影响。当Al2O3厚度由1.5 nm增加到3 nm时,钝化性能得到明显提升,隐开路电压均值提高了20 mV,达到707 mV,对应电池的光电转换效率升高了0.23个百分点,与SiO2/Al2O3(1.5 nm)/SiNx叠层膜电池的转换效率持平。然而,当Al2O3厚度继续增加至5 nm时,隐开路电压均值保持不变。因此可以使用Al2O3(3 nm)/SiNx叠层膜代替SiO2/Al2O3(1.5 nm)/SiNx叠层膜,不仅简化了电池的工艺步骤,而且降低了生产成本。 相似文献
103.
Structural Chemistry - In this work, DFT and TDDFT approaches have been executed to make a detailed exploration about the excited state luminescent properties as well as excited state... 相似文献
104.
采用射频(RF)和单极中频直流脉冲磁控溅射方法,在玻璃基板上制备了(Ti/ZnO)N成分调制纳米多层膜,并研究了调制周期数对其结构及透光导电性能的影响。通过X射线衍射、拉曼光谱、原子力显微镜、紫外可见吸收光谱以及霍尔效应测试结果表明:(Ti/ZnO)N成分调制纳米多层膜以(002)取向的纤锌矿型ZnO结构为主,具有明确的成分调制结构,各Ti层和各ZnO层厚度均匀连续,各界面平整且无明显扩散。在可见光范围的平均透光率大于85%,电阻率最小可达到2.63×10-2 Ω·cm。 相似文献
105.
Huang Tao Yu Lingling Ma Xiaofang Hu Kaifeng 《Analytical and bioanalytical chemistry》2018,410(26):6705-6711
Analytical and Bioanalytical Chemistry - A wide variety of methods, such as enzymatic methods, LC-MS, and LC-MS/MS, are currently available for the concentration determination of plasma glucose in... 相似文献
106.
Kang Sun Meng Liu Junzhe Pei Dr. Dandan Li Dr. Chunmei Ding Prof. Dr. Kaifeng Wu Prof. Dr. Hai-Long Jiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22937-22943
Metal-organic frameworks (MOFs) have been shown to be an excellent platform in photocatalysis. However, to suppress electron–hole recombination, a Pt cocatalyst is usually inevitable, especially in photocatalytic H2 production, which greatly limits practical application. Herein, for the first time, monodisperse, small-size, and noble-metal-free transitional-metal phosphides (TMPs; for example, Ni2P, Ni12P5), are incorporated into a representative MOF, UiO-66-NH2, for photocatalytic H2 production. Compared with the parent MOF and their physical mixture, both TMPs@MOF composites display significantly improved H2 production rates. Thermodynamic and kinetic studies reveal that TMPs, behaving similar ability to Pt, greatly accelerate the linker-to-cluster charge transfer, promote charge separation, and reduce the activation energy of H2 production. Significantly, the results indicate that Pt is thermodynamically favorable, yet Ni2P is kinetically preferred for H2 production, accounting for the higher activity of Ni2P@UiO-66-NH2 than Pt@UiO-66-NH2. 相似文献
107.
Cellulose - Carbon nanotubes (CNTs) have been proposed as next-generation lightweight structural materials, yet their application is facing challenges due to the poor dispersity in most solvents,... 相似文献
108.
Hao Zhengming Zhang Junjie Xie Miao Li Xuechao Wang Lina Liu Ye Niu Kaifeng Wang Junbo Song Luying Cheng Tao Zhang Haiming Chi Lifeng 《中国科学:化学(英文版)》2022,65(4):733-739
Science China Chemistry - Direct coupling or transformation of inert alkanes based on the selective C-H activation is of great importance for both chemistry and chemical engineering. Here, we... 相似文献
109.
Investigation of enzymatic C–P bond formation using multiple quantum HCP nuclear magnetic resonance spectroscopy 下载免费PDF全文
Kaifeng Hu Williard J. Werner Kylie D. Allen Susan C. Wang 《Magnetic resonance in chemistry : MRC》2015,53(4):267-272
The biochemical mechanism for the formation of the C–P–C bond sequence found in l ‐phosphinothricin, a natural product with antibiotic and herbicidal activity, remains unclear. To obtain further insight into the catalytic mechanism of PhpK, the P‐methyltransferase responsible for the formation of the second C–P bond in l ‐phosphinothricin, we utilized a combination of stable isotopes and two‐dimensional nuclear magnetic resonance spectroscopy. Exploiting the newly emerged Bruker QCI probe (Bruker Corp.), we specifically designed and ran a 13C‐31P multiple quantum 1H‐13C‐31P (HCP) experiment in 1H‐31P two‐dimensional mode directly on a PhpK‐catalyzed reaction mixture using 13CH3‐labeled methylcobalamin as the methyl group donor. This method is particularly advantageous because minimal sample purification is needed to maximize product visualization. The observed 3:1:1:3 multiplet specifically and unequivocally illustrates direct bond formation between 13CH3 and 31P. Related nuclear magnetic resonance experiments based upon these principles may be designed for the study of enzymatic and/or synthetic chemical reaction mechanisms. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
110.
Zhang Cankun Zhang Yuzhe Wang Zhiye Su Yuming Wei Zhixiang Hou Jianhui He Shan Wu Kaifeng He Chang Zhang Jianqi Wang Cheng 《中国科学:化学(英文版)》2021,64(9):1569-1576
A bulk heterojunction in organic solar cells is where charge separation and recombination occur. Molecular orientation at the interface is one of the key factors that dictate solar cell efficiency. Although X–ray scattering-based methods can determine donor/acceptor domain orientations between an anisotropic phase and an isotropic fullerene-based phase, the rise of nonfullerene solar cells presents a new challenge in delineating local molecular directions at the interface between two anisotropic donor/acceptor domains. Here, we determine interfacial molecular orientations of three high-efficiency small molecule solar cells(ZR1:Y6, B1:BO–4 Cl, and BTR:BO–4 Cl) using polarization-selective transient absorption spectroscopy. The polarization anisotropy of charge separation dynamics indicates an angle of ~90° between ZR1 and Y6 molecules at the interface, an angle close to 0° between B1 and BO–4 Cl, and random orientations between BTR and BO–4 Cl. These observations provide complementary information to X–ray scattering measurements and highlight polarization-selective transient absorption spectroscopy as a tool to probe interfacial structure and dynamics of key photophysical steps in energy conversion. 相似文献