Equipment-Free Fabrication of Thiolated Reduced Graphene Oxide Langmuir-Blodgett Films: A Novel Approach for Versatile Surface Engineering

Abstract

This research presents a novel method for the fabrication of mercapto reduced graphene oxide (m-RGO) Langmuir-Blodgett (LB) films without the need for specialized equipment. The conventional LB technique offers precise control over the deposition of thin films onto solid substrates, but its reliance on sophisticated instrumentation limits its accessibility. In this study, we demonstrate a simplified approach that circumvents the necessity for such equipment, thereby democratizing the production of m-RGO LB films. Thiolation of reduced graphene oxide (rGO) imparts enhanced stability and functionality to the resulting films, rendering them suitable for a wide range of applications in surface engineering, sensing, and catalysis. The fabricated m-RGO LB films exhibit favorable morphological, structural, and surface properties, as characterized by various analytical techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the performance of the m-RGO LB films is evaluated in terms of their surface wettability, electrochemical behavior, and chemical reactivity. The equipment-free fabrication approach presented herein offers a cost-effective and scalable route for the production of functionalized graphene-based thin films, thus broadening the scope for their utilization in diverse technological applications.

Keywords: Langmuir–Blodgett films; functionalized thin film; thiolated reduced graphene oxide.

Figure 1

Schematic illustration of the procedure for fabricating mercapto reduced oxide (m-RGO) Langmuir–Blodgett (LB) films.

Figure 2

X-ray photoelectron spectroscopy (XPS) spectra of m-RGO: (a) wide scan, (b) high-resolution C1s, (c) high-resolution O1s, and (d) high-resolution S2p.

Figure 3

Secondary electron image (a) and ion images of (b) 12C-, (c) 16O-, and (d) 32S-, and atomic ratio images of (e) C/O, (f) C/S, and (g) S/O. Color changes from blue through green to red indicate increasing intensity. The nano-secondary ion mass spectrometry (NanoSIMS) and elemental ratios mapping image was obtained using a 25 × 25 μm² area on a m-RGO LB film on an Au substrate.

Figure 4

Transmittance (a) and sheet resistance (b) of m-RGO LB films on slide glass, with corresponding photos of the m-RGO LB film (inset in (a)).

Figure 5

Optical profilometry images of (a) and (b) m-RGO Langmuir film on water and (c) m-RGO LB film on glass. The red color in (a) represents water.

Figure 6

AFM height (a) and amplitude (b) images of m-RGO LB film on mica, with the corresponding height profile (c).

Figure 7

Raman spectroscopy of m-RGO LB film. (a) The bright field image of m-RGO LB film, (b) Raman mapping from the red box area of the bright field image, and (c) the averaged Raman spectrum of Raman mapping.