Ratio Of Reduced Graphene Oxide Research Articles

One-step hydrothermal synthesis of surface fluorinated TiO2/reduced graphene oxide nanocomposites for photocatalytic degradation of estrogens

Abstarct The surface fluorinated TiO 2 /reduced graphene oxide (RGO) nanocomposites (denoted as FTG) were synthesized by a facile one-step hydrothermal method. The prepared photocatalysts were characterized by Transmission electron microscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The results showed that, the anatase TiO 2 nanoparticles were well dispersed on RGO sheets, and there was a C–Ti bond in FTG. Moreover, the F − was adsorbed on the surface of TiO 2 , and generated the stable F–Ti bonds. The adsorption ability and photocatalytic activity of the nanocomposites was evaluated by degradation of 17β-estradiol (E2) and 17α-ethynyl-estradiol (EE2) under UV light illumination. The removal ratio was strongly affected by the mass ratio of RGO in FTG, and the optimal mass ratio of RGO for both E2 and EE2 was 4.0 wt% (FTG-4). Further more, the presence of F − enhanced the photocatalytic activity effectively. Under the optimal degradation conditions, the total removal ratios of E2 over FTG-4, TiO 2 /4 wt% RGO (denoted as TG, without adding hydrofluoric acid) and P25 (Commercial TiO 2 ) were 99.8%, 83.3% and 74.4%, respectively. And the total removal ratios of EE2 over the same catalysts were 99.7%, 82.6% and 75.6%, respectively. The results indicated that FTG exhibited much higher efficient removal ability for estrogens compared to TG and P25. The introduction of GO in the TiO 2 can enhance the adsorption ability for estrogens, meanwhile, GO and the F − can both improve the photocatalytic activity of TiO 2 for degradation of estrogens greatly. Further more, the prepared catalyst was found to be reusable.

LDPE/EVA/graphene nanocomposites with enhanced mechanical and gas permeability properties

In the present work, graphene oxide (GO) and reduced graphene oxide (RGO) were incorporated at low‐density polyethylene (LDPE)/ethylene vinyl acetate (EVA) copolymer blend using solution casting method. Monolayer GO with 1‐nm thickness and good transparency was synthesized using the well‐known Hummers's method. Fourier transform infrared and X‐ray photoelectron spectroscopy data exhibited efficient reduction of GO with almost high C/O ratio of RGO. Scanning electron microscopy showed the well distribution of GO and RGO within LDPE/EVA polymer matrix. The integrating effects of GO and RGO on mechanical and gas permeability of prepared films were examined. Young's modulus of nanocomposites are improved 65% and 92% by adding 7 wt% of GO and RGO, respectively. The tensile measurements showed that maximum tensile strength emerged in 3 wt% of loading for RGO and 5 wt% for GO. The measured oxygen and carbon dioxide permeability represented noticeably the attenuation of gas permeability in composite films compared with pristine LDPE/EVA blend. Copyright © 2015 John Wiley & Sons, Ltd.

Gas sensors for CO2 detection based on RGO–PEI films at room temperature

In this paper, polyethyleneimine (PEI) and reduced graphene oxide (RGO) were selected as sensing materials for carbon dioxide detection. Two kinds of sensors with different sensitive film structures, i.e., RGO–PEI composite film and RGO–PEI bi-layer film were fabricated by airbrushing the sensitive films on interdigitated electrodes. Response performances of both sensors at room temperature were investigated. Results showed that sensors with bi-layer film exhibited smaller baseline drift and more stable sensing characteristics than the counterparts with composite film. Furthermore, bi-layer film sensors with different quantity of PEI solution deposited were studied. Performances of long-time stability, repeatability, low concentration of detection for carbon dioxide, and measurements of response time and recovery time were investigated. It was found that appropriate weight ratio of RGO and PEI was critical for sensing response. In addition, the sensor with bi-layer film exhibited a better repeatability but had longer response time and recovery time than RGO single-layer sensor, and both of them could detect as low as 20 parts per million carbon dioxide gas. Sensing responses of the prepared sensors to carbon dioxide under dry air or nitrogen were compared. The relevant sensing mechanisms were studied as well.

A facile route to reduced graphene oxide–zinc oxide nanorod composites with enhanced photocatalytic activity

In this study, highly efficient photocatalysts were synthesized by the successful hybridization of ZnO nanorods (ZnO NRs) with reduced graphene oxide (RGO) by a facile and green hydrothermal process. The photocatalytic experimental results indicated that all the RGO–ZnO NR composite photocatalysts exhibited enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-light irradiation. It is found that the degree of photocatalytic activity enhancement strongly depends on the mass ratio of RGO in the composites; the highest photocatalytic activity which equals to 6.8 times as that of pristine ZnO NRs can be obtained when the loading amount of RGO is 4.0wt.% of RGO. The enhancement of photocatalytic activity can be attributed to the synergistic effect of the effective inhibition of the recombination of photo-generated electron–hole pairs and the elevated absorption ability for dyes, due to the strong electronic interaction between ZnO NRs and RGO nanosheets. Considering the facile and green method for the reduction of GO, the present investigation can be further employed to fabricate more graphene-based composites for various environmental and energy-related applications.

A Photoelectrochemical Investigation on the Synergetic Effect between CdS and Reduced Graphene Oxide for Solar‐Energy Conversion

CdS modified with reduced graphene oxide (RGO) has been widely demonstrated to be effective in the field of solar-energy conversion. However, the inherent mechanism of this superior property is still not thoroughly understood. Thus the photoelectrochemical method was employed to systemically investigate the synergetic effect between CdS and RGO. The result shows that the photoelectrochemical properties of RGO/CdS samples are sensitive to the relative ratio of RGO to CdS, and the photoelectrode with 1.0 wt% ratio of RGO possesses the best photoelectrochemical performance. Further investigation demonstrates that the synergetic effect between CdS and RGO directly influences the charge-transport property and band-structure of the composite, which is also supported by the X-ray photoelectron spectroscopy data and first-principle simulation, respectively.

Nanocomposites of Ni(OH)2/Reduced Graphene Oxides with Controllable Composition, Size, and Morphology: Performance Variations as Pseudocapacitor Electrodes

AbstractAlthough Ni(OH)2 is a promising electrode material for electrochemical capacitors on account of its high theoretical specific capacitance and low cost, its application has been hindered by the low measured specific capacitance and poor cycle stability often associated with low specific surface area and poor electrical conductivity. This study aims to develop an amorphous‐precursor method to anchor Ni(OH)2 nanocrystals onto conductive graphene sheets. We demonstrate the ability to control the composition, size, and morphology of Ni(OH)2 nanocrystals on graphene sheets by combination with an Ostwald ripening process, which has allowed investigation on how such factors influence their performance if used as pseudocapacitor electrodes. It was found that the specific capacitance increased and then decreased as the ratio of reduced graphene oxide (RGO) to Ni(OH)2 increased; the sample that contained 5.2 wt % of RGO achieved the highest specific capacitance of 1804.0 F g−1 (based on the total composite mass) and 1902.9 F g−1 (based on the mass of Ni(OH)2), close to the theoretical value of Ni(OH)2 (2082 F g−1). With a given ratio of RGO to Ni(OH)2, the specific capacitance decreased as the Ni(OH)2 nanocrystal size increased. However, the cycling performance increased as the stability of Ni(OH)2 in the nanocomposites increased; the highest was achieved for the most stable Ni(OH)2 hexagonal nanoplates on RGO. In all, with appropriate optimization of the parameters of the materials, a good pseudocapacitor performance was achieved for the Ni(OH)2/RGO hybrid system in terms of both the specific capacitance and the cycling stability.

Synthesis of polypyrrole-reduced graphene oxide composites by in-situ photopolymerization and its application as a supercapacitor electrode

A highly conductive polypyrrole (PPy)-reduced graphene oxide (RGO) composite with an electrical conductivity of 610 S m−1 was successfully synthesized by the in-situ photopolymerization of pyrrole in a graphene oxide suspension. Graphene oxide (GO) played the role of an electron acceptor and was reduced as it accepted electrons. The reduction of GO was confirmed by the increase in the C/O ratio of RGO with the UV irradiation time as well as the high electrical conductivity of PPy-RGO composite. Through the thermogravimetric analysis, it has been found that the PPy-RGO composite exhibited high thermal stability compared to the GO and PPy. This material was used as an electrode in a supercapacitor cell and showed excellent performance for electrical energy storage. The composite exhibited a specific capacitance of 376 F g−1 at a scan rate of 25 mV s−1.

Reduced Graphene Oxide-Modified Bi<sub>2</sub>WO<sub>6</sub> as an Improved Photocatalyst under Visible Light

A new and improved photocatalyst, reduced graphene oxide (RGO)-modified Bi2WO6 (Bi2WO6-RGO), was synthesized by a two-step hydrothermal process. The effect of RGO content on photoactivity was investigated and the optimum mass ratio of RGO to Bi2WO6 was determined to be 1%. Based on scanning electron microscopic study, RGO does not change the structure and morphology of the Bi2WO6 photocatalyst. Therefore, the improvement in the photoactivity of the Bi2WO6-RGO composite is undoubtedly ascribed to RGO. The presence of graphene can facilitate the dissociation of photogenerated excitons, which leads to more O2●- to degrade dye pollutants like rhodamine-B (RhB). Moreover, the efficient adsorption of RhB molecules on graphene is another reason for the improved photoactivity.