Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits thei...Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits their practical applications. Here atomic layer deposition （ALD） of TiO2 and Al2O3 was performed to deposit an Au/TiO2 catalyst with precise thickness con-trol, and the thermal stability was investigated. We surprisingly found that sub-nanometer-thick Al2O3 overcoat can su ciently inhibit the aggregation of Au particles up to 600 C in oxygen. On the other hand, the enhancement of Au nanoparticle stability by TiO2 overcoat is very limited. Di use reffectance infrared Fourier transform spectroscopy （DRIFTS） of CO chemisorption and X-ray photoelectron spectroscopy measurements both con rmed the ALD overcoat on Au particles surface and suggested that the presence of TiO2 and Al2O3 ALD overcoat on Au nanoparticles does not considerably change the electronic properties of Au nanoparticles. The catalytic activities of the Al2O3 overcoated Au/TiO2 catalysts in CO oxidation increased as increasing calcination temperature, which suggests that the embed-ded Au nanoparticles become more accessible for catalytic function after high temperature treatment, consistent with our DRIFTS CO chemisorption results.展开更多
This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corr...This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corrosion properties than that of reference a-CNx overcoats （2 4.5 nm）. The superior anti-corrosion performance is attributed to its stoichiometric bond structure, where 94.8% Si atoms form Si-N asymmetric stretching vibration bonds. The N/Si ratio is 1.33 as in the stoichiometry of Si3N4 and corresponds to the highest hardness of 25.0 GPa. The surface is atomically smooth with RMS 〈 0.2 nm. The ultra-thin a-SiNx overcoats are promising for hard disks and read/write heads protective coatings.展开更多
The Dandong Yinjian(Silver Arrow)Fashion Co.,Ltd.is a specializedproduction base for men’s overcoats,having advanced production equipment anda rich technical force.The Fushihao brandmen’s overcoats made by the Compa...The Dandong Yinjian(Silver Arrow)Fashion Co.,Ltd.is a specializedproduction base for men’s overcoats,having advanced production equipment anda rich technical force.The Fushihao brandmen’s overcoats made by the Company enjoya high reputation at home and abroad。展开更多
The Thimble King cashmere and wool overcoats made by the Gold Thimble Fashion Company in Dandong City, Liaoning Province, are of international fashion, unique style, selected materials and superb craftsmanship. With t...The Thimble King cashmere and wool overcoats made by the Gold Thimble Fashion Company in Dandong City, Liaoning Province, are of international fashion, unique style, selected materials and superb craftsmanship. With their style and quality in perfect harmony, the overcoats are comfortable and elegant. The company has adopted展开更多
文摘Supported gold nanoparticle catalysts show extraordinarily high activity in many reactions. While the relative poor thermal stability of Au nanoparticles against sintering at elevated temperatures severely limits their practical applications. Here atomic layer deposition （ALD） of TiO2 and Al2O3 was performed to deposit an Au/TiO2 catalyst with precise thickness con-trol, and the thermal stability was investigated. We surprisingly found that sub-nanometer-thick Al2O3 overcoat can su ciently inhibit the aggregation of Au particles up to 600 C in oxygen. On the other hand, the enhancement of Au nanoparticle stability by TiO2 overcoat is very limited. Di use reffectance infrared Fourier transform spectroscopy （DRIFTS） of CO chemisorption and X-ray photoelectron spectroscopy measurements both con rmed the ALD overcoat on Au particles surface and suggested that the presence of TiO2 and Al2O3 ALD overcoat on Au nanoparticles does not considerably change the electronic properties of Au nanoparticles. The catalytic activities of the Al2O3 overcoated Au/TiO2 catalysts in CO oxidation increased as increasing calcination temperature, which suggests that the embed-ded Au nanoparticles become more accessible for catalytic function after high temperature treatment, consistent with our DRIFTS CO chemisorption results.
基金Project supported by the Major Program of the National Natural Science Foundation of China (Grant No 50390060)the National Natural Science Foundation of China (Grant Nos 60576022 and 50572012)
文摘This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corrosion properties than that of reference a-CNx overcoats （2 4.5 nm）. The superior anti-corrosion performance is attributed to its stoichiometric bond structure, where 94.8% Si atoms form Si-N asymmetric stretching vibration bonds. The N/Si ratio is 1.33 as in the stoichiometry of Si3N4 and corresponds to the highest hardness of 25.0 GPa. The surface is atomically smooth with RMS 〈 0.2 nm. The ultra-thin a-SiNx overcoats are promising for hard disks and read/write heads protective coatings.
文摘The Dandong Yinjian(Silver Arrow)Fashion Co.,Ltd.is a specializedproduction base for men’s overcoats,having advanced production equipment anda rich technical force.The Fushihao brandmen’s overcoats made by the Company enjoya high reputation at home and abroad。
文摘The Thimble King cashmere and wool overcoats made by the Gold Thimble Fashion Company in Dandong City, Liaoning Province, are of international fashion, unique style, selected materials and superb craftsmanship. With their style and quality in perfect harmony, the overcoats are comfortable and elegant. The company has adopted
