The dynamic and kinetic evolution of supported metal particles in the presence of reactants is decisive in shaping the nature of the catalytic active sites and the deactivation process. Ostwald ripening of FeO/Pt(111)...The dynamic and kinetic evolution of supported metal particles in the presence of reactants is decisive in shaping the nature of the catalytic active sites and the deactivation process. Ostwald ripening of FeO/Pt(111) supported Au particles in the presence of carbon monoxide is addressed here by firstprinciples kinetics. It is found that CO stabilizes the ripening monomer(Au atom) by forming favorable Au carbonyls with lower total activation energy, and corresponding phase diagram at wide range of temperature and CO pressures is constructed. Evolution of particle number, dispersion and particle size distribution of supported Au particles are explored. Great influence of CO promotion on ripening kinetics is revealed and explored in details, and mbar range of CO can lower the onset temperature of ripening by a few hundred kelvins. The present work reveals the crucial role of the metal-reactant complexes formed under reaction conditions on ripening of metal catalysts.展开更多
The adsorption of CO on Pt group metals, as a most fundamental elementary reaction step, has been widely studied in catalysis and electrocatalysis. Particularly, the structures of CO on Pt(111) have been extensively i...The adsorption of CO on Pt group metals, as a most fundamental elementary reaction step, has been widely studied in catalysis and electrocatalysis. Particularly, the structures of CO on Pt(111) have been extensively investigated, owing to its importance to both fundamental and applied catalysis. Yet, much less is known regarding CO adsorption on a Pt(111) surface modulated by supported oxide nanostructures,which is of more relevance to technical catalysis. We thus investigated the coverage-dependent adsorption of CO on a Pt(111) surface partially covered by Fe Oxnanostructures, which has been demonstrated as a remarkable catalyst for low-temperature CO oxidation. We found that, due to its strong chemisorption, the coverage-dependent structure of CO on bare Pt is not influenced by the presence of Fe Ox. But,oxygen-terminated Fe Oxnanostructures could modulate the diffusivity of CO at their vicinity, and thus affect the formation of ordered CO superstructures at low temperatures. Using scanning tunneling microscopy(STM), we inspected the diffusivity of CO, followed the phase transitions of CO domains, and resolved the molecular details of the coverage-dependent CO structures. Our results provide a full picture for CO adsorption on a Pt(111) surface modulated by oxide nanostructures and shed lights on the inter-adsorbate interaction on metal surfaces.展开更多
A detailed study of the cyclic voltammtry curve of Pt(111) electrode in H2SO4 solution by X-ray photoe1ectron spectroscopy (XPS) and a low energy electron diffeaction (LEED) has provided firstly direct evidence that t...A detailed study of the cyclic voltammtry curve of Pt(111) electrode in H2SO4 solution by X-ray photoe1ectron spectroscopy (XPS) and a low energy electron diffeaction (LEED) has provided firstly direct evidence that the anomalous features reported originally by Clavilier et al. are associated with the specific adsorption of sulfate ainons rather than hydrogen adsorption. The ()R30 structure on Pt(111) obtained after electrode emersion on the positive scan at more positive potentials than 0.23V vs. Ag/AgCl appears sedtaneously with sharp increase of XPS of O1s and S2p. This implies the relationship between anomalous peak and sulfate anion adsorption on emersed Pt(111 ) electrode.展开更多
利用单晶旋转圆盘电极技术(Hanging Meniscus Rotating Disk Electrode,HMRD)在硫酸和高氯酸溶液中,分别研究了甘氨酸修饰的Pt(111)电极表面氧分子的电催化还原反应.实验发现:在硫酸溶液中,经甘氨酸修饰的Pt(111)电极表面的氧还原活性...利用单晶旋转圆盘电极技术(Hanging Meniscus Rotating Disk Electrode,HMRD)在硫酸和高氯酸溶液中,分别研究了甘氨酸修饰的Pt(111)电极表面氧分子的电催化还原反应.实验发现:在硫酸溶液中,经甘氨酸修饰的Pt(111)电极表面的氧还原活性明显提高,其中氧还原的半波电位与Pt(111)电极的相比正移约0.1 V,而在高氯酸溶液中,甘氨酸修饰的Pt(111)电极的活性几乎没有发生变化.该实验结果表明:甘氨酸修饰的Pt(111)电极一方面抑制了SO42-在电极表面的吸附,另一方面又能在电极表面提供相邻的空位供氧分子吸附.通过与文献中报道的CN-修饰的Pt(111)电极上的氧还原结果的对比,可以推测甘氨酸修饰的Pt(111)电极表面氧还原活性提高,是由于甘氨酸在Pt(111)表面可能先被氧化成CN-后吸附在电极表面,进而促进了氧分子的电催化还原反应.展开更多
基金supported by the National Key R&D Program of China(2017YB0602205)the National Natural Science Foundation of China(91645202)the Chinese Academy of Sciences(QYZDJSSW-SLH054)
文摘The dynamic and kinetic evolution of supported metal particles in the presence of reactants is decisive in shaping the nature of the catalytic active sites and the deactivation process. Ostwald ripening of FeO/Pt(111) supported Au particles in the presence of carbon monoxide is addressed here by firstprinciples kinetics. It is found that CO stabilizes the ripening monomer(Au atom) by forming favorable Au carbonyls with lower total activation energy, and corresponding phase diagram at wide range of temperature and CO pressures is constructed. Evolution of particle number, dispersion and particle size distribution of supported Au particles are explored. Great influence of CO promotion on ripening kinetics is revealed and explored in details, and mbar range of CO can lower the onset temperature of ripening by a few hundred kelvins. The present work reveals the crucial role of the metal-reactant complexes formed under reaction conditions on ripening of metal catalysts.
基金financially supported by the Natural Science Foundation of China(21473191,21303195 and 91545204)Ministry of Science and Technology of China(2013CB933100 and 2016YFA0202803)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020200)
文摘The adsorption of CO on Pt group metals, as a most fundamental elementary reaction step, has been widely studied in catalysis and electrocatalysis. Particularly, the structures of CO on Pt(111) have been extensively investigated, owing to its importance to both fundamental and applied catalysis. Yet, much less is known regarding CO adsorption on a Pt(111) surface modulated by supported oxide nanostructures,which is of more relevance to technical catalysis. We thus investigated the coverage-dependent adsorption of CO on a Pt(111) surface partially covered by Fe Oxnanostructures, which has been demonstrated as a remarkable catalyst for low-temperature CO oxidation. We found that, due to its strong chemisorption, the coverage-dependent structure of CO on bare Pt is not influenced by the presence of Fe Ox. But,oxygen-terminated Fe Oxnanostructures could modulate the diffusivity of CO at their vicinity, and thus affect the formation of ordered CO superstructures at low temperatures. Using scanning tunneling microscopy(STM), we inspected the diffusivity of CO, followed the phase transitions of CO domains, and resolved the molecular details of the coverage-dependent CO structures. Our results provide a full picture for CO adsorption on a Pt(111) surface modulated by oxide nanostructures and shed lights on the inter-adsorbate interaction on metal surfaces.
文摘A detailed study of the cyclic voltammtry curve of Pt(111) electrode in H2SO4 solution by X-ray photoe1ectron spectroscopy (XPS) and a low energy electron diffeaction (LEED) has provided firstly direct evidence that the anomalous features reported originally by Clavilier et al. are associated with the specific adsorption of sulfate ainons rather than hydrogen adsorption. The ()R30 structure on Pt(111) obtained after electrode emersion on the positive scan at more positive potentials than 0.23V vs. Ag/AgCl appears sedtaneously with sharp increase of XPS of O1s and S2p. This implies the relationship between anomalous peak and sulfate anion adsorption on emersed Pt(111 ) electrode.
基金supported by the National Natural Science Foundation of China(21503122,21346002)Natural Science Foundation of Shanxi for Youths,China(2014021016-2)+1 种基金Scientific and Technological Programs in Shanxi Province,China(2015031017)Foundation of Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),China~~
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20773116）, the National Instrumentation Program （No.2011YQ03012416）, and 973 Program from the Ministry of Science and Technology of China （No.2010CB923302）.
