Enhancement of CO₂adsorption on oxygen-functionalized epitaxial graphene surface under near-ambient conditions

Abstract

The functionalization of graphene is important in practical applications of graphene, such as in catalysts. However, the experimental study of the interactions of adsorbed molecules with functionalized graphene is difficult under ambient conditions at which catalysts are operated. Here, the adsorption of CO2 on an oxygen-functionalized epitaxial graphene surface was studied under near-ambient conditions using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). The oxygen-functionalization of graphene is achieved in situ by the photo-induced dissociation of CO2 with X-rays on graphene in a CO2 gas atmosphere. The oxygen species on the graphene surface is identified as the epoxy group by XPS binding energies and thermal stability. Under near-ambient conditions of 1.6 mbar CO2 gas pressure and 175 K sample temperature, CO2 molecules are not adsorbed on the pristine graphene, but are adsorbed on the oxygen-functionalized graphene surface. The increase in the adsorption energy of CO2 on the oxygen-functionalized graphene surface is supported by first-principles calculations with the van der Waals density functional (vdW-DF) method. The adsorption of CO2 on the oxygen-functionalized graphene surface is enhanced by both the electrostatic interactions between the CO2 and the epoxy group and the vdW interactions between the CO2 and graphene. The detailed understanding of the interaction between CO2 and the oxygen-functionalized graphene surface obtained in this study may assist in developing guidelines for designing novel graphene-based catalysts.

Surface Chemistry of Carbon Dioxide on Copper Model Catalysts Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy

“…An AP-XPS system at the soft X-ray undulator beamline BL07LSU of SPring-8 [65] has been under operation since 2014. So far, studies on gas-solid interfaces were mainly conducted: CO 2 adsorption on epitaxial graphene/SiC(0001) [66], CO 2 activation and hydrogenation on Cu model catalysts [35,36], and hydrogen adsorption/absorption in Pd-Cu [67] and Pd-Ag foils [68]. Figure 3 shows a schematic diagram of the AP-XPS system [35].…”

Nanoscale fracture of defective popgraphene monolayers

“…The remarkable properties 1-3 and promising applications [4][5][6] offered by two-dimensional (2D) graphene have triggered great scientific interest to discover other 2D carbon allotropes. For example, following the success of graphene, penta-graphene, 7,8 phagraphene, 9,10 phographene, 11 ψ-graphene, 12 and θ -graphene 13 have been intensively studied for exciting applications such as in nanoelectronics and energy storage.…”

High-Performance UV-Assisted NO2 Sensor Based on Chemical Vapor Deposition Graphene at Room Temperature

“…As previously reported, graphene-based materials demonstrated tremendous potential for detecting small-molecule gases, for example, NO 2 , NH 3 , CO 2 , H 2 O, and SO 2 . − Herein, the gas-sensing performance of graphene sensor arrays were detected by choosing NO 2 as the target gas at room temperature. The sensing performance test used a home-made measurement system, as shown in Figure b.…”