Imaging of the Surface of Catalysts by Scanning Probe Microscope.

Abstract

Atomic force microscope (AFM) and electrochemical scanning tunneling microscope (EC-STM) were used to examine the surface structure of zeolites (mordenite, heulandite, Linde Type A) and Cu(111), respectively. The (001) surface of mordenite had several deep grooves and was coated with impurities. After this coating material was scraped off, the ordered pore structure was observed. The surface structure of Linde Type A crystal indicated that the double 4-rings are the building key unit for crystal growth. AFM images of the morphological changes on the (010) surface of heulandite due to dissolution in a 0.2 N H2SO4 aqueous solution revealed the unique dissolution process that resulted from the characteristic pore structure. EC-STM could reveal the surface structure of Cu(111) with electrochemically created hydroxyl species in an alkaline aqueous solution. Two kinds of lattice structures were observed. AFM and EC-STM can provide the microscopic-level information of the surface structure of zeolite and metal catalysts.