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Adsorption of CO 2 on Graphene: A Combined TPD, XPS, and vdW-DF Study

2017; American Chemical Society; Volume: 121; Issue: 5 Linguagem: Inglês

10.1021/acs.jpcc.6b11373

1932-7455

Kaori Takeuchi, Susumu Yamamoto, Yuji Hamamoto, Yuichiro Shiozawa, Keiichiro Tashima, Hirokazu Fukidome, Takanori Koitaya, Kozo Mukai, Shinya Yoshimoto, Maki Suemitsu, Yoshitada Morikawa, Jun Yoshinobu, Iwao Matsuda,

Thermal properties of materials

The adsorption of CO2 molecules on monolayer epitaxial graphene on a SiC(0001) surface at 30 K was investigated by temperature-programmed desorption and X-ray photoelectron spectroscopy. The desorption energy of CO2 on graphene was determined to be (30.1–25.1) ± 1.5 kJ/mol at low coverages and approached the sublimation energy of dry ice (27–25 kJ/mol) with increasing the coverage. The adsorption of CO2 on graphene was thus categorized into physisorption, which was further supported by the binding energies of CO2 in core-level spectra. The adsorption states of CO2 on graphene were theoretically examined by means of the van der Waals density functional (vdW-DF) method that includes nonlocal correlation. The experimental desorption energy was successfully reproduced with high accuracy using vdW-DF calculations; the optB86b-vdW functional was found to be most appropriate to reproduce the desorption energy in the present system.