Supported Au25 clusters were prepared through the calcination of Au25(SC12H25)18 on hierarchically porous carbon nanosheets under vacuum at temperatures in the range of 400–500 °C for 2–4 h. TEM and EXAFS analyses revealed that the thiolate coverage on Au25 gradually decreased with increasing calcination temperature and period and became negligibly small when the calcination temperature exceeded 500 °C. The catalysis of these Au25 clusters was studied for the aerobic oxidation of benzyl alcohol. Interestingly, the selectivity for benzaldehyde formation was remarkably improved with the increase in the amount of residual thiolates on Au25, while the activity was reduced. This observation is attributed to the dual roles of the thiolates: the reduction of the oxidation ability of Au25 by electron withdrawal and the inhibition of the esterification reaction on the cluster surface by site isolation.

Highly selective production of ethylene from bioethanol dehydration over hierarchical ZSM-5 nanosheets.

The superior catalytic performance of amine-grafted hierarchical basic FAU-type zeolite nanosheets for the aldol condensation of 5-hydroxymethylfurfural (5-HMF) and acetone (Ac) has been achieved due to the synergistic effect of hierarchical structures, featuring basic active sites together with surface modification. This results in an unprecedented yield of 4-[5-(hydroxymethyl)furan-2-yl]but-3-en-2-one (HMB) close to 100%. The catalytic activity can be easily tuned by changing the degree of basicity corresponding to the nature of basic sites and surface modification.