Abstract
Nanoscale characterization of the acid properties of H 3PMo 12− x W x O 40 ( x = 0, 3, 6, 9, 12) was carried out by scanning tunneling microscopy (STM) and tunneling spectroscopy. Pyridine binding with the acid sites of heteropolyacids (HPAs) was reflected in both the STM images and FT-IR spectra of these materials. All the HPAs investigated formed well-ordered monolayer arrays on highly oriented pyrolytic graphite (HOPG) before and after pyridine adsorption. Exposure to pyridine increased the lattice constants of the two-dimensional HPA arrays by ca. 6 Å. Exposure to pyridine also shifted the negative differential resistance (NDR) peak voltages of HPAs to less negative values in the tunneling spectroscopy measurements. The NDR shifts of HPAs obtained before and after pyridine adsorption were correlated with acid properties of HPAs for the first time, suggesting that tunneling spectra measured by STM could serve to fingerprint acid properties of HPAs.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
