The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herei...The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herein,we report a novel Cd/TiO_(2) catalyst exhibiting a methanol selectivity of 81%,a CO_(2) conversion of 15.8%,and a CH_(4) selectivity below 0.7%.A combination of experimental and computational studies revealed that the unique electronic properties exhibited by the Cd clusters supported by the TiO_(2) matrix were responsible for the high selectivity of CO_(2) hydrogenation to methanol via the HCOO*pathway at the interfacial catalytic sites.展开更多
Although there are diverse bond features of Ti and O atoms,so far only several isomers have been reported for each(TiO_(2))n cluster.Instead of the widely used global optimization,in this work,we search for the low-ly...Although there are diverse bond features of Ti and O atoms,so far only several isomers have been reported for each(TiO_(2))n cluster.Instead of the widely used global optimization,in this work,we search for the low-lying isomers of(TiO_(2))_(n)(n=2-8)clusters with up to 10000 random sampling initial structures.These structures were optimized by the PM6 method,followed by density functional theory calculations.With this strategy,we have located many more low-lying isomers than thosereported previously.The number of isomers increases dramatically with the size of the cluster,and about 50 isomers were found for(TiO_(2))_(7) and(TiO_(2))_(8) with the energy within 30 kcal/mol.Furthermore,new lowest isomers have been located for(TiO_(2))_(5) and(TiO_(2))_(8),and isomers with three terminal oxygen atoms,five coordinated oxygen atoms as well as six coordinated titanium atoms have been located.Our work highlights the diverse structural features and a large number of isomers of small TiO_(2) clusters.展开更多
Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystal...Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO2 nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.展开更多
文摘The conversion of CO_(2) to methanol with high activity and high selectivity remains challenging owing to the kinetic and thermodynamic limitations associated with the low chemical reactivity exhibited by CO_(2).Herein,we report a novel Cd/TiO_(2) catalyst exhibiting a methanol selectivity of 81%,a CO_(2) conversion of 15.8%,and a CH_(4) selectivity below 0.7%.A combination of experimental and computational studies revealed that the unique electronic properties exhibited by the Cd clusters supported by the TiO_(2) matrix were responsible for the high selectivity of CO_(2) hydrogenation to methanol via the HCOO*pathway at the interfacial catalytic sites.
基金supported by the National Natural Science Foundation of China(No.92061114 and No.21873096)the Chinese Academy of Sciences(XDB17010200)。
文摘Although there are diverse bond features of Ti and O atoms,so far only several isomers have been reported for each(TiO_(2))n cluster.Instead of the widely used global optimization,in this work,we search for the low-lying isomers of(TiO_(2))_(n)(n=2-8)clusters with up to 10000 random sampling initial structures.These structures were optimized by the PM6 method,followed by density functional theory calculations.With this strategy,we have located many more low-lying isomers than thosereported previously.The number of isomers increases dramatically with the size of the cluster,and about 50 isomers were found for(TiO_(2))_(7) and(TiO_(2))_(8) with the energy within 30 kcal/mol.Furthermore,new lowest isomers have been located for(TiO_(2))_(5) and(TiO_(2))_(8),and isomers with three terminal oxygen atoms,five coordinated oxygen atoms as well as six coordinated titanium atoms have been located.Our work highlights the diverse structural features and a large number of isomers of small TiO_(2) clusters.
文摘Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO2 nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.
