This work is focused on determining whether two graphene derivatives: graphene oxide (GO) and reduced graphene oxide (RGO) can be used alone as a component of anticancer therapy. In this paper, we present the synthesis GO and RGO, their physicochemical characterization as well as an evaluation of their cytotoxic properties on cancer (HepG2 and MCF-7) and non-malignant (clone-9 and HMF) cells. We demonstrated that both tested graphene derivatives have a high affinity to cancer cells. We showed that cytotoxic properties of GO and RGO were different depending on the type of solvent in which they were prepared. Additionally, we observed that cytotoxic properties of GO and RGO were different depending on the origin of the cells (liver and breast) and the form of graphene material (GO and RGO). We showed that GO and RGO can be potential, selectively materials which in future can found application in anticancer therapy.

In order to expand the family and improve the bioactivity of oral implant ceramics, the phase structures, mechanical and wetting properties of the hot-pressed yttria-zirconia/multilayer graphene oxide composite (3Y-ZrO2/GO) ceramics were investigated. GO was uniformly distributed in 3Y-ZrO2 powders, forming the C–O–Zr bond during the sintering process. In comparison to raw 3Y-ZrO2 ceramics, the flexural strength and fracture toughness improved up to 200% (1489.96 ± 35.71 MPa) in ZG3 (with 0.15 wt% GO) and 40.9% (8.95 ± 0.59 MPa m1/2) in ZG2 (with 0.1 wt% GO), respectively, while the relative density and Vickers hardness increased slightly. The toughening mechanisms included crack deflection, crack bridging, and GO put-out. Meanwhile, the composite ceramics were transformed into a more hydrophilic direction and indicated a good wetting property. In consideration of mechanical and wetting properties, the ZG3 would be a favorable alternative to the yttria-zirconia ceramic (Y-TZP) in dental implant applications. The results are expected to serve as a technical guidance for the fabrication and evaluation of dental implants.

Integrating LiMn2O4(LMO) and different carbon materials to build a mixed cathode system can provide fast transport channels to improve the conduction of both electrons and ions. In this paper, our work studied in situ low-temperature hydrothermal synthesis of LMO nanocomposites based on graphene oxide (GO)/carbon nanotubes (CNTs) hydrogel. Compared with the pure LMO nanoparticles, GO/CNTs/LMO (GCLMO) composites greatly improved electrochemical performance in specific capacity, cycle performance and rate ability. The electrochemical test results showed that the specific capacitance of GCLMO nanocomposites reached 396 F/g at the current density of 0.5 A/g, which was much higher than 221 F/g of pure LMO. Even at the current density of 10 A/g, the specific capacitance was still as high as 309 F/g. Besides, after 2000 cycles, the specific capacitance retention of the composite was 93%. Electrochemical data showed that GCLMO composite is an ideal cathode material for supercapacitors.

As electrode materials, metal-organic frameworks always have low electrical conductivity and poor structural stability, which limits its applications in electrochemical fields. Here, Ni-BPDC/GO composites are synthesized using graphene oxide (GO) as a substrate and 4,4′-biphenyldicarboxylic acid (BPDC) as an organic ligand via a hydrothermal approach. The growth mechanism of the Ni-BPDC and Ni-BPDC/GO composites is proposed. In the composites, highly dispersed Ni-BPDC macro-nanostrips are supported on the GO surface in parallel. The presence of GO does not affect the growth and crystalline structure of Ni-BPDC. Compared with the Ni-BPDC, Ni-BPDC/GO composites exhibit higher specific capacitance, rate capability, and operating current density through lowering intrinsic resistance, charge-transfer resistance, and ion diffusion impedance. Moreover, the assembled Ni-BPDC/GO-3//reduced graphene oxide (rGO) asymmetric supercapacitor has large specific capacitance, good cycling stability, and high energy density (16.5 W h/kg at 250 W/kg). Hence, Ni-BPDC/GO composites are a potential electrode material for supercapacitors.

Reduced graphene oxide supported titanium dioxide (GO/TiO2) heterojunction composites as highly active photocatalysts were synthesized via simple ultrasonic mixing and hydrothermal reaction using TiCl3 and GO as precursors. Their structure and morphology were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, UV-vis spectroscopy, and thermogravimetic analysis. The GO/TiO2 heterojunction composites were used to degrade methyl orange (MO). The adsorption and photocatalytic degradation rate of the prepared GO/TiO2 composites increased by nearly three times compared with that of pristine TiO2 or GO, which reached up 90%, to degrade MO after 4 h, which provides a simple method to obtain photocatalytic materials.

Traditional dip-assisted layer-by-layer (LbL) assembly produces robust and conformal coatings, but it is time-consuming. Alternatively, spray-assisted layer-by-layer (SA-LbL) assembly has gained interest due to rapid processing resulting from the short adsorption time. However, it is challenging to assemble anisotropic nanomaterials using this spray-based approach. This is because the standard approach for fabricating “all-polyelectrolyte” LbL films does not necessarily give rise to satisfactory film growth when one of the adsorbing components is anisotropic. Here, polymers are combined with a model anisotropic nanomaterial via SA-LbL assembly. Specifically, graphene oxide (GO) is investigated, and the effect of anchor layer, colloidal stability, charge distribution along the carbon framework, and concentration of polymer on the growth and the film quality is examined to gain insight into how to achieve pinhole-free, smooth polymer/GO SA-LbL coatings. This approach might be applicable to other anisotropic nanomaterials such as clays or 2D nanomaterials for future development of uniform coatings by spraying.

A de novo drug delivery nanosystem based on gold nanoparticles (GNPs), decorated poly(ethylene glycol) (PEG), and folate (FA)-conjugated graphene oxide (GO) was designed and developed successfully. Initially, the graphite (G) powder was oxidized to the GO, and then functionalized with chloroacetic acid to afford a carboxylated graphene oxide (GO–COOH). The obtained GO–COOH was functionalized with an amine end-caped PEG, FA, as well as 3-amino-1-propanethiol to produce a GO–PEG–FA–SH. In another experimental section, GNPs were synthesized through a citrate-mediated reduction approach, and subsequently decorated onto/into GO–PEG–FA–SH through the formation of Au–S bond to afford a GO–PEG–FA/GNP nanosystem. The resultant nanosystem was loaded with doxorubicin hydrochloride (DOX) as a model anticancer drug, and its drug-loading capacity as well as pH-dependent drug release behavior were investigated. The anticancer activity of the developed theranostic nanomedicine was extensively evaluated using MTT assay against human breast cancer cells (MCF7). The developed GO–PEG–FA/GNPs–DOX theranostic nanomedicine exhibited an excellent cancer chemotherapy feature. In addition, this nanomedicine can be used in chemo-photothermal therapy of solid tumors because of the presence of GO and GNPs in its structure.

Heterogeneous photocatalytic oxidation technology is currently a technology with the potential to solve environmental pollution and energy shortages. The key to this technology is to find and design efficient photocatalysts. Here, a series of inorganic coordination polymer quantum sheets (ICPQS)@graphene oxide (GO) composite photocatalysts are synthesized by adding GO to the synthesis process of ICPQS: {[CuII(H2O)4][CuI4(CN)6]}n. These composite photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, Zeta potential, and N2 adsorption/desorption isotherms. The photocatalytic degradation of methylene blue showed that the activity of ICPQS@GO composite photocatalysts is better than that of ICPQS. Among ICPQS@GO composite photocatalysts, the 10.6% ICPQS@GO composite photocatalyst has the best activity, which can reach 3.3 mg/(L min) at pH 3. This method of loading low–specific surface area photocatalysts onto GO to improve photocatalytic performance indicates the direction for the synthesis of highly efficient photocatalysts.

The physicochemical properties and broad applications of graphene have been extensively studied, but its preparation method is still a bottleneck, and it cannot simultaneously meet the requirements of low process cost and high quality of products in the time being. In this article, the redox potential was employed to control the quality of graphene prepared from graphene oxide by chemical reduction. The effects of the initial redox potential on the productivity, microscopic morphology, and structural and intrinsic properties of graphene were investigated. Results showed that there was an optimum initial redox potential range between −1200 and −1180 mV. In such a range could the graphene with a high yield be obtained, and layers of graphene products could be stabilized at 1 or 2 layers. Therefore, the redox potential could be used as an effective parameter instead of trying to design orthogonal tests to determine the optimal conditions and control the synthesis of graphene.

We report Electrically reduced graphene oxide (GO) and n-type Si heterostructure junction-based photovoltaic cell. The transition of the insulating properties of GO to that of semi-conducting was achieved by applying electric voltages using 5, 10, and 15 V biasing. The photovoltaic device I–V characteristics corresponding to the increasing (5–15 V) reduction voltages, obtained on exposure of 25 mW/cm2 visible light, showed approximately same fill factor with increased efficiency. The maximum efficiency of 1.12% was observed under ultraviolet light exposure for photovoltaic cell consisting GO reduced using 15 V reduction voltage. GO was synthesized using the modified Hummers’ technique and characterized by X-ray diffraction (XRD), ultraviolet–visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The GO characteristic XRD peak corresponding to plane (001) was observed at 9.16°. The UV-Vis spectrum for GO displayed an absorption peak at 228.5 nm, and the corresponding Tauc plot analysis provided a band gap of 4.74 eV. The FTIR analysis showed presence of C=O (1713 cm−1), C=C (1627 cm−1), C–OH (1418 cm−1), C–O–C (1252 cm−1), C–O (1030 cm−1), and C–H (827 cm−1) functional groups in GO.

Coatings with low friction coefficient and excellent anti-wear and anticorrosion performances are of great interest for fundamental research and practical applications. In the present study, Cobalt–nickel–phosphorus/graphene oxide (Co–Ni–P/GO) composite coating is prepared by a pulse electrodeposition method. Effect of the embedded GO sheets on the microstructures, microhardness, and electrochemical and tribological behaviors of the Co–Ni–P/GO composite coating are researched in detail. The results reveal that the co-deposition of GO sheets significantly improves the microhardness of the as-prepared Co–Ni–P/GO composite coating and changes the morphology of the Co–Ni–P coating from hemispheric structure to nodule structure with smaller globular particles for the Co–Ni–P/GO composite coating. In addition, friction and wear tests show that the incorporation of GO sheets endows the Co–Ni–P/GO composite coating with remarkable friction reduction and improved wear resistance. Electrochemical corrosion tests demonstrate that the Co–Ni–P/GO composite coating possesses better corrosion resistance than the Co–Ni–P coating.

Composite hydrogels based on hydroxypropyl cellulose (HPC) and graphene oxide (GO) were developed and used for adsorption of phenol. The single network composite hydrogel (SNCH) was first prepared by crosslinking of HPC and GO by epichlorohydrin; then the SNCH was treated with polyethyleneimine solution, forming the double network composite hydrogel (DNCH). The DNCH exhibited better adsorption capacity than the SNCH due to larger surface area and more functional groups. The possible adsorption mechanism of the composite hydrogels toward phenol involved electrostatic, hydrogen bonding, and π–π interactions. Study on dynamic adsorption behavior of phenol by SNCH and DNCH indicated that the breakthrough time increased when the initial concentration and feed flow rate of phenol decreased. Furthermore, the breakthrough time of DNCH was longer than that of SNCH at all operating conditions due to the relatively higher adsorption capacity of DNCH. The SNCH and DNCH could be repeatedly used without significant loss in the initial binding affinity after six adsorption–desorption cycles, which indicated that the composite hydrogels were qualified for practical application.

Solar steam generation is an efficient and green technology for desalination and drinking water purification, however, impeded by high cost, low efficiency, and complicated process. Black titania is expected to exhibit excellent solar steam performance due to its outstanding light absorption properties, chemical stability, low cost, and innocuity. Herein, we design a high absorbing and efficient solar steam generation system based on a black titania/graphene oxide nanocomposite film affixed to airlaid paper wrapped over the surface of expandable polyethylene foam; the system possesses several important criteria required for the ideal solar steam generator: wide-spectrum absorption, adequate water supply, reduced heat loss for localized water heating, and porous structure for steam flow. Remarkably, we realized a solar thermal conversion efficiency of 69.1% under illumination of 1 kW/m2 without solar concentration, and the device delivered remarkable cycle stability.

Poly(lactic acid) (PLA)/graphene oxide (GO) nanocomposites were prepared by solution mixing. Differential scanning calorimetry results indicated that GO was an effective nucleating agent. The size of spherulites decreased, the density of spherulites increased with increasing GO and the crystallinity of PLA increased from 4.34 to 49.01%. For isothermal crystallization, the crystallization rates of PLA/GO nanocomposites were significantly higher than that of neat PLA, in which t 0.5 reduced from 9.0 to 2.8. Spindle-like nanopores (about 100–200 nm) that arranged like spherulites were prepared by low temperature foaming. It was found that the crystallization rate increase and spherulite morphology change were insignificant when the content of GO exceeded 0.5 wt%, because the excessive GO increased the number of nucleation sites while restricting the PLA crystal growth. Thus, the arrangement of nanopores did not mimick the spherulites because of imperfect crystal morphology.

A three-dimensional nanostructured graphene oxide–Mn3O4 hybrid was synthesized by a coprecipitation method and used as an anode material of lithium ion batteries, which reached an initial specific capacity of 1400 mA h/g. This method was developed to simplify the process of fabricating uniform composite nanomaterials for abundant applications. In this work, Mn3O4 particles were coordinately distributed on the surface of reduced graphene oxide nanosheets to avoid detrimental stacking of graphene layers by forming 3D nanostructures, as characterized by a scanning electron microscope. As demonstrated by the in situ observation of a scanning probe microscope, severe pulverization of Mn3O4 particles during charge/discharge processing was significantly abstained when graphene layers constrained swelling and shrinkage. The as-prepared graphene–Mn3O4 nanomaterials exhibited a large specific capacity of 949 mA h/g, high-rechargeable efficiency of ∼98%, and exceptional cyclic stability. After 100 constant-current charging/discharging cycles at 100 mA/g, the specific capacity remained at 792 mA h/g with a coulombic efficiency of 98.1%. Furthermore, the coprecipitation method proposed in this work provides a strategy to fabricate other nanostructured composites for different kinds of applications.

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

We describe the synthesis and fabrication of a graphene oxide (GO) and single-walled carbon nanotube (SWCNT) composite ink (GO–SWCNT ink) for electrochemically stable supercapacitors. Atomic force microscopy and scanning electron microscopy studies demonstrate that the obtained GO flakes are single layer with size distribution from 100 nm to 20 μm. SWCNTs are dispersed using a GO aqueous solution (2 mg/mL) with sonication support to achieve a SWCNT concentration of 12 mg/mL, the highest reported value so far without surfactant assistance. Raman spectroscopy studies indicate that the full-width at half-maximum of the G band increases with the mixing of SWCNT and GO indicating that electronic structure changes via π–π interactions of GO sheets and SWCNTs. Paper-based electrodes of supercapacitor were conveniently fabricated with GO–SWCNT composite ink via a dip casting method. By using different concentrations of SWCNT in the ink, the paper electrodes provide different capacitance values. The highest value of specific capacitance reaches 295 F/g at a current density of 0.5 A/g with a GO/SWCNT weight ratio of 1:5. The cycling stability for the GO–SWCNT paper electrode supercapacitors indicates capacitance retention of 85% over 60,000 cycles.

In this work, a novel core–shell structured hybrid graphene oxide-encapsulated silica (GO–SiO2) was first fabricated via an electrostatic assembly between negatively charged graphene oxide (GO) sheets and positively charged sub-micro-sized silica. Then, the new kind of hybrid filler was used for the in situ preparation of poly(ethylene terephthalate) (PET)/GO–SiO2 composites. The microstructure and mechanical properties of the prepared composites were analyzed by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, dynamic mechanical analysis measurements, and tensile test. It was found that GO could be covalently assembled onto the subsized silica surface via its plenty of functional groups that can also provide strong interaction with the PET. As a result, a uniform dispersion of GO–SiO2 hybrids and enhanced interfacial adhesion as well as improved mechanical property have been evidenced. The new concept of using GO as a potent inorganic fillers surface modifier may broaden the use of GO and provides a new idea for the design and fabrication of advanced polymer composites.

Graphite oxide (GO) is generated by treating graphite with strong oxidizers. GO retains the structure of graphite, but does so with a larger and irregular basal plane spacing. The oxidation of graphite results in the formation of epoxide groups, as well as C–OH and COOH groups. It is the presence of some of these moieties that allows GO to be dispersed in water, allowing for its use in waterborne formulations. Although GO does not possess the electrical properties of single-sheet graphene, it can be swelled in water, which allows for intercalation of hydrophilic polymer between GO sheets, resulting in a composite that can be coated to produce a continuous film. After coating it may be possible to chemically convert GO to a reduced graphite oxide (r-GO) with improved electrical conductivity. X-ray diffraction (XRD) is ideally suited to evaluate GO–polymer composite samples for evidence of intercalation or exfoliation of GO. Examples of GO–polymer analysis by XRD are presented, along with results that demonstrate the effect of relative humidity (RH) on neat GO. Knowing the ambient RH during XRD data collection was found to be important to correctly assess the extent of polymer intercalation within the GO lattice.