Reduced Graphene Oxide Titania Research Articles

Bench-scale photoelectrocatalytic reactor utilizing rGO-TiO2 photoanodes for the degradation of contaminants of emerging concern in water

Pharmaceuticals and personal care products are contaminants of emerging concern (CEC) in water. Photocatalysis (PC) and photoelectrocatalysis (PEC) are potential advanced oxidation processes for the effective degradation of these contaminants. In this work a bench-scale photoelectrocatalytic reactor utilizing a UVA-LED array was designed and tested for the degradation of diclofenac as a model CEC. Reduced graphene oxide-titanium dioxide (rGO-TiO2) composite, prepared by the photocatalytic reduction of rGO on TiO2, was immobilised on fluorine doped tin oxide (FTO) glass and evaluated as a photoanode. The influence of UVA intensity and rGO:TiO2 ratio on the degradation rate was studied. Surface modification of the TiO2 with 1% rGO gave the highest photocurrent and best degradation rate of diclofenac, as compared to unmodified TiO2. However, following repeat cycles of photoelectrocatalytic treatment there was an observed drop in the photocurrent with rGO-TiO2 anodes and the rate of diclofenac degradation decreased. Raman and XPS analysis indicated the re-oxidation of the rGO. Attempts to regenerate the rGO in-situ by electrochemical reduction did not prove successful, suggesting that the site of photoelectrocatalytic oxidation of rGO was different to the reduction site targeted in the photocatalytic reduction for the formation of the rGO-TiO2 composites.

Cesium lead iodide-decorated two-dimensional titanium dioxide/reduced graphene oxide nanofiber composites as photoanodes for inorganic perovskite solar cells

In this study, we developed photoanode materials based on inorganic cesium lead iodide (CsPbI3)-decorated two-dimensional titanium dioxide-reduced graphene oxide nanofibers (TiO2/rGO NFs22TiO2/rGO NFs - titanium dioxide-reduced graphene oxide nanofibers.) for perovskite solar cells (PSCs). CsPbI3 was prepared by a two-step solution process and TiO2/rGO NFs were prepared using the electrospinning method. The influence of the as-fabricated TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite on their optical, surface, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet–visible–near-infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy analyses. XRD analysis of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite showed a crystalline nature with cubic and anatase crystal faces. The surface morphology of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite appeared as a beat-free fiber with a polycrystalline nature. The chemical oxidative states and electronic structures of the electrospun TiO2/rGO NFs were determined by X-ray photoelectron spectroscopy analysis. PSCs device were assembled with TiO2 NFs, TiO2/rGO NFs as photoanode, 2,2′,7,7′-Tetrakis(N,N-di-P-methoxyphenylamine)− 9,9′-spirobifluorene (Spiro–OMeTAD) as hole transport materials, sputtered gold chloride as back electrode (counter electrode). In addition, the CsPbI3 perovskite coated on the electrospun TiO2 and TiO2/rGO NF photoanodes exhibited electrical conductivities of 1.352 × 10−3 and 1.650 × 10−3 S cm−1. Finally, power conversion efficiency of TiO2/rGO NFs (6.38 %) was achieved, which was significantly higher than that of conventional TiO2 NFs (5.54 %)-based devices.

Reduced graphene oxide-TiO2/sodium alginate/polyacrylamide composite hydrogel for enhanced adsorption-photocatalytic degradation of methylene blue

The discharge of dye wastewater from various industries has emerged as a critical environmental concern, necessitating the implementation of effective methods such as photocatalytic technology to mitigate organic dyes in water. Nevertheless, the poor photocatalytic activityability and low reusability of most semiconductor photocatalysts have hindered their large-scale practical application. In this paper, the reduced graphene oxide-titanium dioxide composite (rGO-TiO2) was prepared via a hydrothermal method and subsequently immobilized onto a three-dimensional structure composed of sodium alginate (SA) and polyacrylamide (PAM) through sunlight-induced polymerization and ionic cross-linking techniques, resulting in the fabrication of a novel photocatalytic composite hydrogel (rGO-TiO2/SA/PAM). The composite hydrogel was found to exhibit good photocatalytic degradation efficiency for methylene blue(MB), achieving complete removal of MB under UV light irradiation for 100 min at pH 7 when using a rGO:TiO2 ratio of 3 wt%. Additionally, the synthesis of rGO-TiO2/SA/PAM effectively harnesses solar resources through simple synthetic steps, enabling easy recovery and separation from dye wastewater (with a recovery rate of approximately after first use). In contrast, nano-TiO2 and rGO-TiO2 exhibit lower recovery rates (∼80%). Furthermore the material demonstrates enhanced selective adsorption-photocatalytic degradation of MB in acid-base dye mixtures under UV light irradiation.

Plant-based synthesis of TiO2 – rGO nanocomposite for the efficient photocatalytic degradation of an emerging contaminant: Experimental and theoretical investigations

The need to develop sustainable and efficient photocatalysts for the degradation of contaminants of emerging concern has gained considerable attention. In this study, plant-based titanium dioxide-reduced graphene oxide (TiO2-rGO) photocatalyst was synthesized by a hydrothermal method using Azadirachta indica (AI) leaf extract. Morphological and chemical properties of the AI-TiO2-rGO photocatalyst were evaluated in detail. The clusters of AI-TiO2 wrapped in AI-rGO were identified with TEM analysis, and from the XRD, the purity of AI-TiO2-rGO was confirmed. The low band gap (2.80 eV) of AI-TiO2-rGO made it a suitable photocatalyst under visible light. The X-ray photoelectron spectroscopy (XPS) results indicated the establishment of strong Ti-O-C chemical linkage within the AI-TiO2-rGO photocatalyst. The efficiency of AI-TiO2-rGO was assessed for the degradation of carbamazepine (CBZ) under UV-A irradiation (94.28%) and visible light (59.97%) in a batch photocatalytic reactor for 60 min. The optimized conditions such as AI-TiO2-rGO dosage (50 mg/L), initial CBZ concentration (4.5 mg/L), and light source (UV-A (60 W)), were validated with response surface methodology (RSM). The mechanism of degradation of CBZ by AI-TiO2-rGO was explained with the identification of intermediate compounds, and three plausible CBZ degradation pathways were proposed. The reusability study suggested that the AI-TiO2-rGO photocatalyst could be effectively used for 8 cycles. The evaluation of toxicity of treated water with E.Coli growth curve (reduction in Iind to 30.12% (UV) and 27.65% (visible)) signified that the treated water was less toxic. The comparison of AI-TiO2-rGO with chemically synthesized TiO2-rGO indicated that even though AI-TiO2-rGO exhibited a slightly higher band gap (2.80 eV), it can be the better alternative for the photocatalysts synthesized by chemical route. The economic analysis of the overall process proved that the application of AI-TiO2-rGO was more cost-effective and sustainable than the conventional TiO2 photocatalyst. Overall, the study provides valuable insight into synthesizing recyclable plant-based photocatalysts to degrade recalcitrant emerging contaminants in the water.

Geometrical Characterisation of TiO2-rGO Field-Effect Transistor as a Platform for Biosensing Applications.

The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on the output drain current (Id). In this work, the signal-to-noise ratio (SNR) was investigated to obtain a high-performance device that produces a higher Id value. Using the finite element method, a novel top-gate FET was developed in a three-dimensional (3D) simulation model with the titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposite as the transducer material, which acts as a platform for biosensing application. Using the Taguchi mixed-level method in Minitab software (Version 16.1.1), eighteen 3D models were designed based on an orthogonal array L18 (6134), with five factors, and three and six levels. The parameters considered were the channel length, electrode length, electrode width, electrode thickness and electrode type. The device was fabricated using the conventional photolithography patterning technique and the metal lift-off method. The material was synthesised using the modified sol-gel method and spin-coated on top of the device. According to the results of the ANOVA, the channel length contributed the most, with 63.11%, indicating that it was the most significant factor in producing a higher Id value. The optimum condition for the highest Id value was at a channel length of 3 µm and an electrode size of 3 µm × 20 µm, with a thickness of 50 nm for the Ag electrode. The electrical measurement in both the simulation and experiment under optimal conditions showed a similar trend, and the difference between the curves was calculated to be 28.7%. Raman analyses were performed to validate the quality of TiO2-rGO.

A novel electrochemical ion imprinting sensor modified with carbon nanocomposites and its high selectivity for cadmium ion detection in real samples

AbstractDue to their high toxicity, potential for bioaccumulation and carcinogenicity, heavy metal pollutants have harmed the environment. Cadmium is a dangerous heavy metal that can accumulate easily in the human body. Long‐term exposure to cadmium‐contaminated environments can result in numerous diseases. A novel electrochemical sensor based on multi‐walled carbon nanotubes (MWCNTs)–imprinted polymer and reduced graphene oxide–titanium oxide (rGO@TiO2) is reported which was used to detect cadmium ions in actual samples in a highly sensitive and precise method. By using the surface imprinting technique to adhere the imprinted polymer to the surface of the MWCNTs, the template removal rate and cavity utilization rate are increased. At the same time, the electron transfer rate is increased by the MWCNTs’ superior electrochemical performance and higher conductivity. Transmission electron microscopy was used to characterize the composite's morphology. Cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy were used to describe the imprinted polymer's electrochemical behavior. The findings demonstrate the sensor's excellent cadmium ion selectivity. Under ideal experimental conditions, the electrochemical sensor has a good linear relationship in the range of 10−9 to 10−6 mol L−1, and the detection limit is 1.12 × 10−9 mol L−1. The novel sensor offers outstanding repeatability and stability in addition to good selectivity and sensitivity. Eventually, real samples were successfully used to apply the electrochemical sensor for the detection of trace Cd(II) (river water, tap water and rice). © 2023 Society of Industrial Chemistry.

H2 production through glycerol photoreforming using one-pot prepared TiO2-rGO-Au photocatalysts

This work is focused on the optimization of the solar photo-reduction method employed for the preparation of titanium dioxide-reduced graphene oxide (TiO2-rGO) composites with the simultaneous gold nanoparticles photo-deposition. The photocatalytic performances are investigated in terms of hydrogen production by glycerol photoreforming under UV and simulated solar irradiation. Under UV light the TiO2-rGO sample prepared with two hours of solar irradiation shows the best photocatalytic activity, with an hydrogen production rate of 64 mmol H2 h−1 gcat−1, while under simulated solar light the best performance is obtained with the one-hour treated sample (1.6 mmol H2 h−1 gcat−1), due to the smaller gold particle size (around 10 nm) that allows to better exploit the Surface Plasmon Resonance (SPR) effect of gold. The Raman characterization reveals how the GO reduction degree plays a fundamental role in the photocatalytic activity of these samples. Furthermore, the presence of the gold nanoparticles allows a better control of the reduction process together with the co-catalytic action. Finally, EDX-STEM images demonstrated how this kind of preparation leads to a good gold dispersion on the catalyst surface. GO solar photo-reduction can be an easy and cheap alternative method to prepare photo-active materials having suitable properties for the photocatalytic hydrogen production.

Synthesis of a powerful single copper/tungsten atom oxide photocatalyst dispersed on the surface of a reduced graphene oxide-titanium composite for H2 production and pollutant degradation

The specific activity and selectivity of many catalytic processes have been frequently enhanced, making single-atom catalysis a new frontline in the area of catalysis. In this study, a powerful photocatalyst was synthesized for H2 production and ofloxacin (OFL) degradation, utilizing a catalytically active TiO2-reduced graphene oxide (rGO) support material. A Cu mono-substituted heteropoly acid(HPA) was used to generate surface-dispersed single copper/tungsten atom oxide (SCu/WAO) sites as co-catalysts. Many single atoms were homogeneously deposited on the TiO2-rGO catalyst. A TiO2-SCu/WAO-rGO catalyst was successfully prepared, and the presence of the SCu/WAO species was confirmed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), extended X-ray absorption fine structure (EXAFS), and X-ray absorption near edge structure (XANES) analyses. The prepared photocatalyst was found to facilitate high rates of H2 production (14.32 mmol/g/h) and a high maximum OFL degradation (98.4%). Additionally, it could effectively substitute current noble metal catalysts as an extremely effective and long-lasting solar radiation-based photocatalyst for renewable H2production and OFL degradation.

An Advanced Quaternary Composite for Efficient Water Splitting

Electrochemical water splitting is a promising pathway for effective hydrogen (H2) evolution in energy conversion and storage, with electrocatalysis playing a key role. Developing efficient, cost-effective and stable catalysts or electrocatalysts is critical for hydrogen evolution from water splitting. Herein, we evaluated a graphene-modified nanoparticle catalyst for hydrogen evolution reaction (HER). The electrocatalytic H2 production rate of reduced graphene oxide-titanium oxide-nickel oxide-zinc oxide (rGO–TiO2–NiO–ZnO) is high and exceeds that obtained on components alone. This improvement is due to the presence of rGO as an electron collector and transporter. Moreover, a current density of 10 mA/cm2 was recorded at a reduced working potential of 365 mV for the nanocomposite. The electronic coupling effect between the nanoparticle components at the interface causes the nanoparticle's hydrogen evolution reaction catalytic activity.Graphical

Facile Green Preparation of Reduced Graphene Oxide Using Citrus Limetta-Decorated rGO/TiO2 Nanostructures for Glucose Sensing

The important electrochemical measurements of reduced graphene oxide-titanium oxide (rGO)/TiO2) electrodes for the application of a glucose sensor are reported in the proposed work. Investigating the sensitivity, stability, and reproducibility of sensor electrodes that were made and used to evaluate the concentration of glucose in the serum is one of the novel aspects of this work. This study presents the use of citrus limetta (sweet lime) fruit peel waste to synthesize a green reduction of graphene oxide (rGO). The rGO/TiO2 composite obtained using the microwave heating method is applied for measuring the structural and morphological properties by various means. A conducting fluorine-tin oxide substrate is used to modify the enzymeless glucose sensor electrode. The electrochemical measurements of rGO/TiO2 sensor electrodes are carried out using the technique of cyclic voltammetry. The rGO/TiO2 sensor electrode exhibits a high sensitivity of 1425 µA/mM cm2 towards glucose concentration in the range of 0.1 to 12 mM. The sensor was found to be extremely stable and repeatable with a response time of 5 s along with a minimum detection limit of 0.32 μM of glucose. The rGO/TiO2 sensor shows relative standard deviation (RSD) of 1.14%, 1.34%, and 1.3% which reveals its excellent stability, repeatability, and reproducibility respectively. The sensor was used for glucose level detection in natural blood serum and shows an RSD of 1.88%. which is in good agreement with the commercial glucose sensor values.

Construction of ultrasensitive electrochemical sensor using TiO2-reduced graphene oxide nanofibers nanocomposite for epinephrine detection

A facile sensing platform was established for the electrochemical detection of epinephrine using titanium dioxide-reduced graphene oxide nanofibers (TiO2-rGO NFs) nanocomposite modified glassy carbon electrode. The TiO2-rGO NFs were prepared using electrospinning followed by hydrothermal method, characterized by various state-of-the-art techniques, and the fabricated sensor were characterized by cyclic voltammetry and differential pulse voltammetry. Using the optimal experimental conditions potential scan rate, linear correlation between analytical signal and concentration of 10–100 nM with a detection limit of 8.11 nM, and sensitivity 0.126 µA µM−1 were observed. The constructed sensor were evaluated the sensing of epinephrine in human serum and drug injection samples. The developed electrochemical sensor provides a potential candidate for the accurate sensing of epinephrine in biological fluids and pharmaceutical drugs.

Titanium Dioxide–Reduced Graphene Oxide Composites for Photocatalytic Degradation of Dyes in Water

Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO2-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO2-RGO were characterized using various technical approaches. The degradation effect of TiO2-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO2-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO2, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO2-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO2-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO2-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.

Real-time monitoring of cellular Ca2+ efflux with renewable graphene field effect transistor biosensor

Calcium ion (Ca2+) is not only an intracellular second messenger, but also functions as an important messenger outside cells for intercellular communications. It is significant to develop a tool for dynamically probing the release of Ca2+ in the extracellular microenvironment. Here we present a photocatalysis-induced renewable reduced graphene oxide nanosheet field effect transistor (rGON-FET) biosensor for real-time monitoring of extracellular Ca2+ release. The biosensing channel was assembled layer-by-layer with reduced graphene oxide nanosheet (rGON) and titanium dioxide-reduced graphene oxide composites (TiO2-RGO) as a sandwich conducting nanostructure. Importantly, this biosensor was capable of measuring the dynamic extracellular Ca2+ release in a real time manner after immobilization of Ca2+ specific binding molecule Fluo 4-AM on the channel interface, particularly within the nano-confined space between the sensor surface and cell bottom. It was found that this biosensor could achieve a detection limit down to 100 pM in phosphate-buffered saline (PBS), and 1 nM in fetal bovine serum (FBS), respectively. Such a functional nanosensor also showed high selectivity to Ca2+ in the presence of excessive amounts of other metal ions. By using photo-responsive self-cleaning TiO2-based nanointerface, this renewable biosensor could be recycled to detect the exocytotic Ca2+ repeatedly. These advantages allow the rGON-FET biosensor to be further used in environmentally and clinically related metal ions detection.

A Selective Electrochemical Sensor Based on Titanium Dioxide-Reduced Graphene Oxide Nanocomposite (TiO2- RGO/GCE) for the Efficient Determination of Nitrite

ABSTRACT A nitrite sensing platform has been constructed using a TiO2-reduced graphene oxide (RGO) nanocomposite incorporated into a glassy carbon electrode. Reduced graphene oxide is integrated in a simple technique for the manufacture of titanium dioxide (TiO2). Spectroscopic and electrochemical techniques have all been used to characterise the TiO2- RGO nanocomposite. In 3 mM and pH 6.0 phosphate buffer solutions, the TiO2-reduced graphene oxide nanocomposites tailored glassy carbon electrode demonstrated outstanding electro-catalytic nitrite oxidation activity. The square root of scan rate is also proportional to the oxidation peak current, showing that the nitrite redox reaction involves a diffusion-controlled mechanism. Using linear sweep voltammetry, the sensitivity and detection limit for nitrite at the modified electrode were determined to be 4.853 μA/μM cm2 and 0.006 µM respectively, over a concentration range of 10 - 2000 µM. Further, the nanocomposite is used to measure NO2- in water and buttermilk samples quantitatively.

Photocatalytic performance of textiles coated with titanium dioxide-reduced graphene oxide system for degradation of crude petroleum under similar solar irradiation

Photocatalytic performance of textiles coated with titanium dioxide-reduced graphene oxide system for degradation of crude petroleum under similar solar irradiation

Exploring engineering reduced graphene oxide-titanium dioxide (RGO-TiO2) nanoparticles treatment to effectively enhance lutein biosynthesis with Chlorella sorokiniana F31 under different light intensity

The Chlorella sorokiniana F31 is a promising lutein producer with high lutein content. Herein, different graphene/TiO2 nanoparticles (NPs) were designed and synthesized by hydrothermal method. Through the UV–vis diffuse reflectance spectra (DRS) analysis, the results showed that RGO-TiO2 NPs can effectively expand visible light absorption compared with TiO2 NPs. Subsequently, the effects of these NPs on light utilization and lutein accumulation of C. sorokiniana F31 were investigated, and the RGO-TiO2 NPs treatment exhibited the higher lutein production and content than that of TiO2 and control group. As the optimal RGO-TiO2 (0.5 wt%) NPs concentration of 50 mg/L and light intensity of 211 μmol/m2/s, the supreme lutein content (15.55 mg/g), production (77.2 mg/L) and productivity (12.87 mg/L/d) were achieved. The performances are higher than most of reported values in previous study, indicated that RGO-TiO2 (0.5 wt%) NPs treatment is a promised strategy to enhance microalgal growth and lutein accumulation.

TiO2-rGO Composite for Photocatalytic Decolorization of Methylene Blue Under the Visible Light Illumination

Titanium dioxide-reduced graphene oxide (TiO2-rGO) was synthesized by hydrothermal method using TiO2 powder and rGO precursor from graphite rod by modified Marcano Method. The obtained TiO2-rGO photocatalyst was characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Diffuse reflectance UV (DRUV). Based on XRD diffractogram, it is known that TiO2 has an anatase crystal phase. In the FTIR spectrum, it was observed that there was an absorption peak at the wavenumber of 1630 cm-1 from the vibration (C=C) as an indication that the C atom was incorporated into the TiO2 structure. The incorporation of C atoms into the TiO2 structure to form TiO2-rGO causes the bandgap energy to decrease from 3.29 eV to 3.20 eV. The photocatalytic activity was tested against decolorization of methylene blue solution for 180 minutes under visible light illumination from a 50 watt LED lamp. Every 10 minutes, absorbance was measured using a UV-Vis spectrophotometer at a wavelength of 664 nm. TiO2-rGO photocatalyst has better photocatalytic activity with %D of 96.39% under UV light and 84.32% under visible light illumination, while TiO2 is only able to degrade 93.87% and 36.55%, respectively.

One-Pot Synthesis of TiO2-rGO Photocatalysts for the Degradation of Groundwater Pollutants.

A non-conventional approach to prepare titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposites based on solar photoreduction is here presented. The standard hydro-solvothermal synthesis of the TiO2-rGO composites requires high temperatures and several steps, whereas the proposed one-pot preparation allows one to obtain the photocatalysts with a simple and green procedure, by exploiting the photocatalytic properties of titania activated by the solar irradiation. The TiO2-rGO catalysts were tested in the solar photodegradation of a widely adopted toxic herbicide (2,4-Dichlorophenoxyacetic acid, 2,4-D), obtaining the 97% of degradation after 3 h of irradiation. The as-prepared TiO2-rGO composites were more active compared to the same photocatalysts prepared through the conventional thermal route. The structural, optical, and textural properties of the composites, determined by Raman, Photoluminescence, Fourier Transform InfraRed (FTIR), UV-vis diffuse reflectance (DRS) spectroscopies, and N2 absorption-desorption measurements, showed as the solar irradiation favors the reduction of graphene oxide with higher efficiency compared to the thermal-driven synthesis. Furthermore, the possible toxicity of the as-synthesized composites was measured exposing nauplii of microcrustacean Artemia sp. to solutions containing TiO2-rGO. The good results in the 2,4-D degradation process and the easiness of the TiO2-rGO synthesis allow to consider the proposed approach a promising strategy to obtain performing photocatalysts.

Reduced graphene oxide-titanium dioxide compact layer prepared via electrodeposition for enhanced performance of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) as one of the third generation of solar cells have gained great attention due to their inexpensive, easy to fabricate and environmental friendliness. In this study, a reduced graphene oxide-titanium dioxide (rGO-TiO2) compact layer (CL) was prepared by one-step electrodeposition. The presence of the rGO-TiO2 CL had successfully suppressed the dark current and shifted its onset potential to a higher forward bias, indicating a good blocking ability. The photoanode with the rGO-TiO2 CL displayed an improved power conversion efficiency by 96.60% compared to other photoanodes. The incorporation of the rGO-TiO2 CL also increased the electron lifetime and charge collection efficiency compared to the bare TiO2 photoanode. These results demonstrated that rGO-TiO2 CL is a promising material for the enhancement of DSSC performance.

Robust self-cleaning effects of cotton fabrics coated with reduced graphene oxide (RGO)-titanium dioxide (TiO2) nanocomposites

The self-cleaning textiles coated with reduced graphene oxide-titanium dioxide (TiO2) nanocomposites have enhanced photocatalytic activities and could have great potential in practical applications. However, it is still problematic regarding how to avoid aggregation of reduced graphene oxide nanosheets in producing reduced graphene oxide-TiO2 nanocomposites. In this research article, we propose a new method to reduce the aggregation of reduced graphene oxide nanosheets in producing cotton fabrics coated with reduced graphene oxide-TiO2 nanocomposites by combining vibration-assisted ball milling and hydrothermal synthesis process. The microstructure and photocatalytic-related properties of the resultant reduced graphene oxide-TiO2 nanocomposites and their coating cotton fabrics were characterized by using a series of techniques including field emission scanning electron microscope (FESEM), atomic force microscope (AFM), X-ray diffraction spectroscopy (XRD), Raman, particle size distribution, Brunauer-Emmett-Teller,(BET), transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS), diffuse reflectance spectra (DRS), ultraviolet photoelectron spectroscope (UPS), and photoluminescence (PL). It was indicated that the aggregation of reduced graphene oxide nanosheets in reduced graphene oxide-TiO2 nanocomposites was successfully avoided via ball milling in the presence of tetrabutyl titanate. After hydrothermal treatment, the resulting reduced graphene oxide-TiO2 nanocomposites were firmly immobilized on cotton fabric. It was demonstrated in the self-cleaning experiments that the resultant self-cleaning cotton fabrics are hydrophilic and could directly decompose color contaminants such as methylene blue, Congo red, and coffee stains under simulated sunlight irradiation due to the photo-degradation reactions of the reduced graphene oxide-TiO2 nanocomposite coating. The reduced graphene oxide-TiO2 nanocomposite-modified cotton fabric also exhibited excellent performance in both robust abrasion resistance and soap-washing resistance. The fabric photocatalytic self-cleaning capability was not found to decrease significantly after being repeatedly used for five times.