Study On The Catalytic Performance Of Au₂₅（MPA）₁₈ Nanoclusters Supported On Different Morphologies Of Nano Ceria

In this paper,Au₂₅（MPA）₁₈ nanoclusters supported on nano CeO₂ with different morphologies.The catalysts were characterization by XRD、XPS、TEM,which is then used for catalytic oxidation of styrene,The effects of different morphologies of CeO₂ on catalytic performance were investigated.At the same time,different supports were synthesized,then Au₂₅（MPA）₁₈ nanoclusters were loaded on different supports.The effects of different supports on the catalytic performance were investigated.These basic work will be helpful to study the catalytic mechanism from many angles,and provide an effective model for the structure-activity relationship of the basic catalysis.The main contents of this paper include:（1）CeO₂ nanorods,nano particles,nanocubes and nano octahedrons were synthesized by hydrothermal method.The TEM results showed that:（a）Nanorods were 100¹50nm in length and 20 nm in diameter,are exposed to high activity of {100} and {110} plane and preferential growth along the [110] direction;（b）Nano particles were 150 nm in diameter,composed of many small grain which diameter in 10²0nm,main exposure {111} surface;（c）Nanocubes size was about 150 nm,the surface exposed to high activity of {100} plane（d）Nano octahedrons size was 40 ⁶0nm,the surface exposed eight stable {111} plane.（2）HAuC_l4·3H₂O as gold salt precursor,3-mercaptopropionic acid（MPA）as ligand,NaOH as PH regulator,NaBH₄ as reducing agent to synthesize Au₂₅（MPA）₁₈nanoclusters.The UV spectra of 400 nm,450nm and 672 nm have obvious absorption peaks,which are consistent with the theoretical calculation and the reports in the literature.TEM results showed that the size of Au₂₅（MPA）₁₈ nanoclusters was 2±0.2 nm.（3）Au₂₅（MPA）₁₈ nanoclusters was loaded on the CeO₂ with different morphologies.In the oxidation of styrene,the nano CeO₂ with different morphologies all can significantly improve the catalytic activity,among of them nanorods was best.The catalytic activity of the catalyst was also improved after heat treatment,which was attributed the bare gold atoms provide more active sites after removal of the thiol ligand.（4）TiO₂、SiO₂、HAP、CeO₂ as supports,Au₂₅（MPA）₁₈ nanoclusters supported on differentsupports.In the catalytic oxidation of styrene,the Au（25）/CeO₂ catalysts exhibition the highest catalytic activity,followed by Au₂₅/HAP and Au₂₅/TiO₂,the lowest was Au₂₅/SiO₂.It can be seen that the supports plays an important role in the catalytic reaction,which is caused by the interaction between the carrier and the gold cluster.