Graphene Oxide Hybridised TiO2 for Visible Light Photocatalytic Degradation of Phenol

Abstract

In industrial pollutants, phenol is a kind of degradation-resistant hazardous compound. It is generated during industrial processes in factories and treatment at sewage plants. In this study, we analyse the photocatalytic activity of TiO2 and rGO as a composite for the degradation of phenol. Hybridised titanium dioxide/reduced graphene oxide (TiO2/rGO) nanocomposites were synthesised by a simple hydrothermal method using flake graphite and tetrabutyl titanate as raw materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) specific area analysis, Fourier transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), photoelectrochemical analysis, and UV–vis diffuse reflectance spectra (DRS) were employed to characterise the physicochemical properties of the as-prepared nanocomposites. The results showed the TiO2/rGO nanocomposites’ significant anatase phase and a small fraction of the rutile phase the same as that of the as-prepared TiO2 nanoparticles. The spherical TiO2 nanoparticles (diameter 20–50 nm) were agglomerated slightly and the agglomerates were anchored on the rGO sheets and dispersed symmetrically. The specific surface area of TiO2/rGO-4% nanocomposites was 156.4 m2/g, revealing a high specific surface area. Oxygen-containing functional groups that existed in TiO2/rGO-4% nanocomposites were almost removed during hydrothermal processing. The photocurrent response of TiO2/rGO-4% was strongest among the TiO2/rGO nanocomposites, and the bandgap of TiO2/rGO-4% was 2.91 eV, showing a redshift of absorption into the visible region, which was in favour of the high photocatalytic activity of TiO2/rGO nanocomposites under visible light (λ > 420 nm). Moreover, the samples were employed to photodegrade phenol solution under visible light irradiation. TiO2/rGO-4% nanocomposite degraded the phenol solution up to 97.9%, and its degradation rate constant was 0.0190 h−1, which had higher degradation activity than that of other TiO2/rGO nanocomposites. This is a promising candidate catalyst material for organic wastewater treatment.

Enhanced Photocatalytic H2 Generation by Light‐Induced Carbon Modification of TiO2 Nanotubes

“…[19,54] A beneficial effect on kinetics (electron transport, electron-hole recombination) and photocatalytic activity of the carbon-containing TiO 2 photocatalysts is achieved by the removal of the oxygen-containing functional groups. [55,56] Figure 5 shows the incident photon to current efficiency (IPCE) spectra of the TiO 2 NTs and the C-TiO 2 NTs before and after UV light illumination in 0.1 M Na 2 SO 4 electrolyte. The highest IPCE value of 66 % at λ = 353 nm was obtained with the C-TiO 2 -4hUV NTs.…”

“…Namely, when the carbon with oxygen functional groups is exposed to UV light in the presence of TiO 2 , it can undergo photodegradation, losing carbon (previous reports, in which graphene or GO on TiO 2 , subjected to UV illumination underwent first reduction and then photodegradation) [19,54] . A beneficial effect on kinetics (electron transport, electron‐hole recombination) and photocatalytic activity of the carbon‐containing TiO 2 photocatalysts is achieved by the removal of the oxygen‐containing functional groups [55,56] …”

“…[ 19 , 54 ] A beneficial effect on kinetics (electron transport, electron‐hole recombination) and photocatalytic activity of the carbon‐containing TiO 2 photocatalysts is achieved by the removal of the oxygen‐containing functional groups. [ 55 , 56 ]…”

Computational, Investigational Explorations on Structural, Electro-Optic Behavior of Pelargonidin Organic Colorant for TiO2 Based DSSCs

“…The natural dye extracted from Tectona grandis seeds containing pelargonidin pigment as an acceptor exhibited stronger solar cell response in the 300-500 nm spectral region. The external quantum efficiency at any wavelength λ is [33,34]:…”

Recent Developments in Heterogeneous Photocatalysts with Near-Infrared Response

“…However, due to the fast recombination of electrons and holes and limited active catalytic sites on surface, the solar energy conversion efficiency is suppressed to a quite low level (even <1%), which dramatically hinders the practical applications of photocatalysis [12]. Another reason comes from the common use of photocatalytic materials with wide bandgaps such as TiO 2 and ZnO (~3.2 eV), which only respond to UV light consisting of a small part (5%) of solar energy [13][14][15][16]. Consequently, visible and near-infrared (NIR) light, which accounts for 46% and 49% of solar energy respectively, is hugely wasted [17].…”