Influence of rGO and Preparation Method on the Physicochemical and Photocatalytic Properties of TiO2/Reduced Graphene Oxide Photocatalysts

Abstract

In this study, a series of TiO2/rGO photocatalysts were obtained with a two-step procedure: a solvothermal method and calcination at 300–900 °C in an argon atmosphere. It was noted that the presence of rGO in photocatalysts had an important role in the changes in crystallite size and specific surface area. In TiO2/rGO samples, different surface functional groups, such as C−Cgraph, C−Caliph, C−OH, C=O, and CO(O), were found. It was observed that rGO modification suppressed the anatase-to-rutile phase transformation. The photocatalytic activity of the obtained nanomaterials was investigated through the decomposition of methylene blue under UV and artificial solar light irradiation. It was found that the adsorption degree played an important role in methylene blue decomposition. The experimental results revealed that TiO2/rGO samples exhibited superior removal efficiency after calcination for methylene blue compared toTiO2 without rGO, as well as a commercial photocatalyst KRONOClean 7000. It was noted that photocatalytic activity increased with the increase in the calcination temperature. The highest activity was observed for the sample calcined at 700 °C, which consisted of 76% anatase and 24% rutile. This study clearly demonstrated that TiO2/rGO samples calcined in argon can be used as efficient photocatalysts for the application of methylene blue decomposition.

A highly sensitive room temperature liquefied petroleum gas (LPG) sensor with fast response based on a titanium dioxide (TiO2)–reduced graphene oxide (r-GO) composite

“…The high-resolution C 1s spectrum was deconvoluted into nonoxygenated C (CC/C-C) in the aromatic rings of rGO (284.5 eV) and oxygenated C such as that belonging to the -O-CO functional groups (288.8 eV) and to the -C-OH/C-O-C functional groups (286.7 eV) of the reduced graphene oxide. 33,59 Three peaks were observed in the deconvoluted high-resolution spectrum of Ti 2p. Among them, the peaks centered at around 458.8 eV and 464.7 eV could be attributed to the Ti 2p 3/2 and Ti 2p 1/2 spin-orbit splitting photoelectrons, respectively, of tetravalent titanium (Ti 4+ state).…”

“…Carbon nanomaterials, due to their interesting physicochemical properties such as large specific surface area, high adsorption capacity, porous structure, etc., have been frequently investigated for structure-property modulation. 33 Among various carbon-based nanomaterials, graphene, a 2D material with exceptional mechanical strength, electronic, optical, and thermal properties, and large surface area, has been particularly attractive for modulating the gas sensing properties of various metal oxides. Although graphene and graphene-based derivatives (such as graphene oxide (GO) and reduced graphene oxide (r-GO)) themselves have excellent selectivity in sensing gases like NO 2 and ammonia, they suffer from limitations such as low selectivity, poor recovery time, and long-term drift, thus limiting their real-life applications.…”

“…Tin oxide decorated rGO, reported by Mao et al, is one of the earliest such materials, where the sensor showed decent activity in sensing an oxidizing gas (NO 2 ) but its response was lower than that of rGO for a reducing gas such as NH 3 . 39 Coupling r-GO with TiO 2 has been a productive strategy in various applications such as photocatalysis where the sp 2 hybridized sheets act as both an electron receptor and electron transporter, thus preventing excessive recombination of photogenerated charge carriers; 33,[40][41][42] heavy ion removal where the wrinkled and squiggled sheets create efficient contact of the metal oxide nanoparticles along with preventing their agglomeration, thus enhancing their activity; 43 nitrogen fixation to NH 3 where the TiO 2 -rGO hybrid nanocomposite has a lower charge transfer resistance and faster kinetics during the electrocatalysis reaction; electrochemical sensing of ions such as nitrite 44 and hormone ingredients such as epinephrine; 45 high voltage supercapacitors; [46][47][48] antimicrobial and self-cleaning coatings of textile materials; 49 dye-sensitized solar cells where applying r-GO as an interfacial layer between the substrate and TiO 2 resulted in enhanced charge transfer and reduced carrier recombination; 50 water splitting reaction; 51 binders in cement where TiO 2 helps in the dispersibility of r-GO, 52 etc.…”

Synergistic Remediation of Organic Dye by Titanium Dioxide/Reduced Graphene Oxide Nanocomposite

“…After the first, second, and third cycles, the photocatalytic activity of the prepared photocatalyst decreased slightly, from 99.20% to 95.00% and 93.61%, respectively. The reduction in the effectiveness of photocatalytic activity was caused by the blocking of active sites on the photocatalyst surface due to the adsorption of MB molecules, even though the photocatalysts were washed with ultrapure water and ethanol between cycles [60]. Throughout the photocatalytic stability cycles, a slight change in the color of the photocatalyst was observed.…”

Microcystis@TiO2 Nanoparticles for Photocatalytic Reduction Reactions: Nitrogen Fixation and Hydrogen Evolution

“…Photocatalytic reduction reactions (such as hydrogen evolution, nitrogen fixation, and carbon dioxide reduction) can often store the solar energy into chemical energy [19][20][21][22][23][24][25]. As one of the most widely studied photosensitive materials, Titanium dioxide (TiO 2 ) is of great concern in the research of photocatalysis [26][27][28][29][30][31][32][33][34]. Several decades of research have proven the outstanding properties of TiO 2 in photocatalysis, such as low cost, non-toxicity, and excellent stability.…”