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排序方式： 共有1808条查询结果，搜索用时 15 毫秒
71.
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Dr. Xiang Li Dr. Junjun Zhang Jingjing Dou Mengyang Li Xiaohua Feng Ge Liu 《ChemCatChem》2022,14(17):e202200599
Constructing Ni@Pd nanocatalysts can effectively improve the catalytic efficiency of Pd atoms. However, it is difficult to grow Pd atoms uniformly on the Ni surface due to the large lattice mismatch between Ni and Pd. Herein, we demonstrate that the well-defined Ni@Pd nanocatalysts can be obtained by the galvanic replacement reaction between Ni and Pd at room temperature. By simply regulating the content of Pd precursor in the galvanic replacement reaction, the atomic percentages of Pd can be controlled from 2 % to 9 %. In synthesized Ni@Pd nanocatalysts, the Ni@Pd0.06 core-shell nanocrystals show the highest mass activity (1186 mA mgPd−1) and specific activity (4.21 mA cm−2), which are 5.6 times and 2.6 times higher than that of the commercial Pd/C nanocatalyst (212 mA mgPd−1, 1.60 mA cm−2). The enhanced performance is mainly attributed to the synergistic effect between Pd and Ni and the core-shell nanostructure. 相似文献
73.
Caixia Li Jiatong Liu Zheli Wu Zhe Chen Jingwen Jiang Zhengkang Dou Xiaoyu Liu Ming Fu Dawei He Yongsheng Wang 《Advanced Optical Materials》2021,9(22):2100778
It is significant but challenging to develop a 3D colloidal assembly method for optical metamaterials. Hyperbolic metamaterials (HMMs) with 3D porous periodic morphologies are suitable for loading functional components for energy harvesting and biosensing and for providing a tunable range of indefinite permittivity. In this study, porous HMMs with 3D periodicities are constructed from directionally assembled silica nanorods with conformal coating of metal. The indefinite dielectric ranges around visible wavelength are formed from the anisotropic geometry induced anisotropic effective permittivity along different directions and are tunable according to the rod length, rod diameter, and thickness of metal coating. The negative refraction of rod array based metamaterials is verified using the transmission ratio between the part beam and full beam in microscope–spectrum system with incident light beam. The rod-based metamaterials show a higher optical absorption in near-ultraviolet and visible wavelengths than the compared colloidal sphere assembled structures. The porous HMMs loaded with TiO2 can provide enhanced optical absorption and photocatalytic performances. The structures coated with 180–190 atomic-layer-deposition cycles of TiO2 and 8–9 min deposition of silver provide the best performance. 相似文献
74.
Wenzhi Wang Langyuan Wu Zhiwei Li Kangsheng Huang Ziyang Chen Chen Lv Prof. Hui Dou Prof. Xiaogang Zhang 《ChemElectroChem》2021,8(11):2014-2021
Residual lithium on the surface and the resulting side reactions for high-energy-density Ni-rich layered oxide cathodes principally impede their industrial application and trigger safety concerns. Herein, the successful construction of LiBO2−B2O3 co-modified single-crystal LiNi0.6Co0.2Mn0.2O2 (SC-NCM) as a lithium-ion battery (LIB) cathode is reported. Boric acid reacts with the surface residual lithium species to form such uniform coating on the SC-NCM particles, which presents advanced rate and cycling capabilities. As the cathode materials for LIBs, LiBO2−B2O3 co-modified SC-NCM delivers a 141.9 mAh g−1 discharge specific capacity at 5 C between 3.0 and 4.5 V versus Li+/Li with 61.4 % capacity retention after 500 cycles, superior to the 20.8 % retention for the pristine SC-NCM cathode. Besides, the LiBO2-B2O3 protective layer substantially inhibits the unexpected phase transformation, effectively alleviates the mechanical microcracks, and stabilizes the cathode-electrolyte interface, even at an extended operational potential window. The proposed microstructure-modified SC-NCM cathode provides an affordable and feasible design strategy for Ni-rich SC-NCM cathodes towards stable electrochemical performance and prolonged service life at high potential. 相似文献
75.
Shasha Dou Chuan Hu Luyan Shi Wanyu Zhang Shuqing Zhou Puxuan Yan Dr. Lawrence D'Souza Dr. Tayirjan Taylor Isimjan Prof. Xiulin Yang 《ChemCatChem》2021,13(16):3628-3635
The high-efficiency multifunctional materials have considerable significance in the area of sustainable energy to developing a cross-usable and low-cost catalyst. Nevertheless, substantial challenges are ahead on designing and synthesizing a high performance in a scalable and straightforward manner. Here, we have developed a novel bifunctional catalyst based on Ru/CoP nanoboxes (NBs) prepared using ZIF-67 as a precursor. The nano hollow box structure and the strong electronic interaction between Ru clusters and CoP component are confirmed. The Ru/CoP NBs as a catalyst show excellent activities for catalytic NaBH4 hydrolysis such as high turnover frequency (1202.2 min−1), and small electrocatalytic H2 evolution overpotential (49 mV@10 mA cm−2) under ambient conditions. Besides, Ru/CoP NBs also display good stability and reusability. The excellent catalytic performance of Ru/CoP NBs is attributed to the synergy between Ru clusters and CoP species as well as the unique morphology that accelerates charge transfer, provides higher active surface area, and facilitates solute transport and gas emission. 相似文献
76.
New results in SN methyl transfer reaction in the series of Δ2-imidazoline with and without quaternary salt catalyst are reported. The hydrolysis of monocyclic compounds containing the 2-alkyl thio, uronium group leads to the formation of a salt. Rearrangement reactions observed in the “uncatalysed reaction” may be due to a true catalytic reaction. 相似文献
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Bunkuoy Ly Henri J. M. Dou Mme Parina Hassanaly Jean Verducci 《Journal of heterocyclic chemistry》1977,14(7):1275-1277
Alkylation by phase transfert catalysis of ambidents anions of the N-C-0 type, leads to a mixture of N and O substitution. Isomers per cent are 20% for O alkylation and 80% for N alkylation when primary halides are used. With secondary halides, these figures are 35% and 65%. In both cases the overall yield ranges around 60%. 相似文献