| AVS 63rd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Monday Sessions |
| Session 2D+MI-MoA |
| Session: | Dopants, Defects and Interfaces in 2D Materials |
| Presenter: | Takahiro Kondo, University of Tsukuba, Japan |
| Authors: | T. Kondo, University of Tsukuba, Japan R. Shibuya, University of Tsukuba, Japan D. Guo, University of Tsukuba, Japan J. Nakamura, University of Tsukuba, Japan |
| Correspondent: | Click to Email |
Nitrogen doped carbon materials are known to have CO2 adsorption property at room temperature under atmospheric pressure. Recently, we have clarified that the CO2 adsorption property is created by the one of the specific type of nitrogen dopants, pyridinic-N, which has two N-C bonds based on the temperature programmed desorption (TPD) measurements of CO2 from nitrogen-doped graphene nanosheets (N-GNS) and nitrogen-doped model graphite (N-HOPG) catalysts [1]. According to our scanning tunneling microscopy and spectroscopy (STM/STS) measurements of N-HOPG, the CO2 adsorption sites are suggested as the carbon atoms next to the pyridinic-N, where the distinct localized states are formed at near the Fermi level in the occupied region as non-bonding pz orbital of carbon which plays a role of Lewis base site [2]. Furthermore, based on the X-ray photoelectron/absorption spectroscopy, we found that the adsorbed CO2 is lying flat on the N-HOPG surface [3]. In this work, we reports the kinetics of CO2 adsorption on both N-GNS and N-HOPG. From the measurements of CO2-TPD, the desorption temperatures of CO2 have been found to be 373 K in both N-GNS and N-HOPG, indicating that the same Lewis base sites are formed on N-GNS and N-HOPG. The adsorption energy can be roughly estimated as 100 kJ/mol from the desorption temperature. The relatively small adsorption energy can be attributed to the larger activation barrier and/or small pre-exponential (frequency) factor for CO2 adsorption. The adsorption probability of CO2 at 300 K has been estimated to be as 1/100 for N-HOPG. The detail kinetics as well as the selectivity for the CO2 adsorption among many type of mixture gas will be presented.
[1] D. Guo, R. Shibuya, C. Akiba, S. Saji, T. Kondo, J. Nakamura, Science 351 (2016) 361.
[2] T. Kondo, S. Casolo, J. Nakamura et al., Phys. Rev. B 86 (2012) 035436.
[3] H. Kiuchi, R. Shibuya, T. Kondo, J. Nakamura,et al.,Nano. Res. Lett. 11 (2016) 127.