Structural changes in graphene oxide induced by silver nanoparticles – TERS study
Prompong Pienpinijtham (a,b,c,*), Sanpon Vantasin (a), Oraporn Wong-u-ra (b), Yasutaka Kitahama (a), Sanong Ekgasit (b,c) and Yukihiro Ozaki (a,*)
a) Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.
b) Sensor Research Unit (SRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
c) Research Network NANOTEC-CU on Advanced Structural and Functional Nanomaterials, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Abstract
This work has investigated structural changes of graphene oxide (GO) in silver/graphene oxide (AGO) nanocomposites using tip-enhanced Raman scattering (TERS), which is a combination technique of surface-enhanced Raman scattering (SERS) and scanning probe microscopy (SPM). Based on SERS, a Raman spectrum of trace molecules adsorbed on rough metal surfaces/nanoparticles can be collected. On the other hand, nano-scaled topology of samples can be bestowed by SPM. As a result, TERS provides benefits of those two techniques, enabling one to determine molecular information of diminutive samples at specific nano-scaled areas. Because of this markedly high spatial resolution of the TERS technique, the structural changes of GO in AGO can be achieved by constructing line-profile TERS spectra straight from the center of silver nanoparticles (AgNPs) on GO layers. The results show evidences that AgNPs cause shortening of C–C bonds beneath AgNPs, flattening of GO layers, and critical bending on GO layers. Additionally, a connection of carbon atoms via C–C network subsequently expands structural changes with the distance of 200–250 nm from the center of AgNPs, even though this distance is larger than the size of AgNPs. The proposed model of GO structural changes opens new understanding about changes in properties from GO to AGO nanocomposites, which will contribute to a development of advanced nanostructures/nanocomposites in the near future.
Keywords: Tip-enhanced Raman scattering (TERS), Graphene oxide (GO), Silver nanoparticles (AgNPs), Silver/graphene oxide (AGO) nanocomposites, Structural changes.
Topic: DV-Xa Method