Light-Induced Tunable n-Doping of Ag-Embedded GO/RGO Sheets in Polymer Matrix

Abstract

A series of composites were synthesized having graphene oxide (GO)/reduced graphene oxide (RGO), decorated with Ag halide within inert poly­(vinyl alcohol) (PVA) matrix. A calculated amount of cuprous iodide was also synthesized with Ag halide. On exposure to light, due to the photochromic effect, Ag halide converts into Ag nanoparticles as a donor, whereas cuprous iodide acts as a hole trapper to introduce a band gap in graphene. With increasing exposure time, the Ag nanoparticles increase in size and number and composites become increasingly dark. The appearance of the plasmonic peak in ultraviolet–visible plots after exposure to light confirms the presence of Ag nanoparticles in these composites. The apparent red shift of the surface plasmon resonance peak, reduction of its intensity, and broadening of the peak are dependent on the dielectric constant of the surrounding matrix and the distance between the GO/RGO sheet and the Ag nanoparticles. The increasing number and size of Ag nanoparticles introduce tunable n-type doping in the GO/RGO–PVA composites, as determined directly by Raman spectroscopy, without the necessity of electrically gated device.

V2O5–Fe3O4/rGO Ternary Nanocomposite with Dual Applications as a Dye Degradation Photocatalyst and OER Electrocatalyst

“…In addition to the aforementioned results of XRD and FTIR analyses, Raman spectroscopy is also employed to provide more complementary information about the chemical structure of the V 2 O 5 –Fe 3 O 4 /rGO ternary nanocomposite, as shown in Figure S1 (Supporting Information). The presence of D and G bands belonging to graphene oxide can be strongly observed at 1473 and 1583 cm –1 , respectively . Furthermore, the peaks identified at wavenumbers 385, 458, and 597 cm –1 relate to the Fe–O vibration mode of Fe 3 O 4 nanoparticles .…”

“…The presence of D and G bands belonging to graphene oxide can be strongly observed at 1473 and 1583 cm −1 , respectively. 64 Furthermore, the peaks identified at wavenumbers 385, 458, and 597 cm −1 relate to the Fe−O vibration mode of Fe 3 O 4 nanoparticles. 65 Also, the existence of two strong peaks at 525 and 693 cm −1 are assigned to the O−V−O bending vibration modes of V�O bending, and specific peaks at 298 and 990 cm −1 confirm the presence of V�O.…”

A 3D mutilayer curved plasmonic coupling array with abundant and uniform hot spots for surface-enhanced Raman scattering

“…Graphene, the most representative 2D material with excellent optical, mechanical and electrical characteristics, has been applied widely in field-effect transistors [1,2], optical devices [3], solar cells [4] and various sensors [5][6][7]. It has also been ued to tune plasmon dispersion according to optical and electrical properties, which has demonstrated that graphene is an important candidate for surface plasmon resonance (SPR) sensors [8], especially surface-enhanced Raman scattering (SERS) sensors [9][10][11][12][13][14][15]. For example, recent works on graphene-based SERS substrates have been extensively reported [16][17][18][19][20].…”