Investigation of the adsorption properties of borazine and characterisation of boron nitride on Rh(111) by electron spectroscopic methods

• Published in: Applied surface science 2015-11, Vol.354, p.367-372
• Main Authors: Farkas, A.P., Török, P., Solymosi, F., Kiss, J., Kónya, Z.
• Format: Article
• Language: English
• Subjects: Adsorption; Borazine; Boron nitride; Dehydrogenation; Finishes; h-BN; HREELS; Hydrogen storage; Methanol; Methyl alcohol; Single crystals; Surface chemistry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.05.060

•We provided fingerprint data by Auger electron spectroscopy that makes it possible to differentiate between adsorbed borazine multilayer and h-BN overlayer.•The strong characteristic surface phonon losses in HREELS indicate the production of well defined boron nitride nanomesh on Rh(111).•Methoxy species were stable even above room temperature on BN covered Rh(111) and desorbed from the surface after recombination reactions with hydrogen. The adsorption and dissociation of borazine were investigated on Rh(111) single crystal surface by Auger electron spectroscopy (AES), high resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD) methods. Borazine is one of the most frequently applied precursor molecules in the preparation process of boron nitride overlayer on metal single crystal surfaces. On Rh(111) surface it adsorbs molecularly at 140K. We did not find any preferred orientation, although there is evidence of “flat” and perpendicular molecular geometry, too. Dehydrogenation starts even below 200K and finishes until ∼7–800K. No other boron or nitrogen containing products were observed in TPD beyond molecular borazine. Through the hydrogen loss of molecules hexagonal boron nitride layer forms in the 600–1100K temperature range as it was indicated by AES and the characteristic optical phonon HREEL losses of h-BN overlayer. The adsorption behaviour of the boron nitride covered surface was also studied through the adsorption of methanol at 140K. HREELS and TPD measurements showed that methanol adsorbed molecularly and a fraction of it dissociated to form surface methoxy and gas phase hydrogen on the h-BN/Rh(111) surface.