Low-temperature synthesis of graphite flakes and carbon-based nanomaterials from banana peels using hydrothermal process for photoelectrochemical water-splitting

Abstract

Herein, we report the synthesis of carbon nanostructures from banana peels at low hydrothermal temperatures. A one-step hydrothermal method was used, and the desired product was obtained at 220 °C using two dispersant solvents (distilled water (S1) and ethanol (S2)). The formation of carbon nanomaterials and graphite flakes has been confirmed through various characterization techniques. The Scanning Electron Microscopy (SEM) analysis shows a graphite flake-like morphology using water as a solvent and a mix-up of graphite flakes and carbon nanoparticles presence using ethanol as a solvent. Two primary elements i-e., carbon (C) and oxygen (O) were observed in the Energy Dispersive X-ray (EDX) analysis. The X-ray Diffraction (XRD) analysis shows the graphitic diffraction peak that confirms the formation of graphite flakes and carbon nanomaterials with good crystallinity . Fourier Transform Infrared (FTIR) analysis reveals the signature of O–H, C–H, C–O, C–O 2 , bonds along with C O and C C bonds. UV–Visible (UV–Vis) spectroscopy shows absorption at 230 nm for (S2) and 270 nm for (S1) which correspond to the π-π* and n-π* transitions of C C and C O, respectively. The photoelectrochemical (PEC) analysis shows that the sample (S2) has a higher photocurrent density and low charge-transfer-resistance than the sample (S1) because of its finer size. The study thus provides a simple pathway for the preparation of carbon-based nanomaterials on a large scale. • Graphite flakes and carbon-based nanostructures were prepared through a one-step hydrothermal route from banana peels. • Two dispersant solvents i-e, ethanol and water were used as a media in the reaction procedure. • SEM reveals graphite flakes and nanoparticle shape morphology while XRD shows the graphitic peak (002) with good crystallinity. • FTIR shows the signature of C–H, C–O, C–O 2 bonds along with C O and C C bonds. • Photoelectrochemical analysis shows higher photocurrent density and flat-band potential, and low charge-transfer-resistance for the sample prepared in ethanol.