•Porous zeolite chitosan (Zel/Chi) monoliths with ordered porous structure were fabricated.•Their porous structure can be adjusted.•They can load and release drugs as scaffolds.•They can adsorb metal ions and form useful catalysts.Ordered porous zeolite/chitosan (Zel/Chi) monoliths were prepared by a unidirectional freeze–drying method, and their properties and structures were characterized by various instrumental methods. The metal ion adsorption and the drug release performance of the porous Zel/Chi monoliths were also studied. The release rate of cefalexin from drug-loaded Zel/Chi monoliths depended on the composition and porous structure of the monoliths. The metal ion adsorption capacity of the Zel/Chi monoliths was related to the concentration of the metal ions, the adsorption time and the Zel/Chi ratio. An experimentally maximum adsorption of 89 mg/g was achieved for Cu2+ ions. The Zel/Chi monoliths with adsorbed Cu2+ ions effectively catalyzed the reduction of 4-nitrophenol to 4-aminophenol and had good recyclability. They were easily recovered by simply removing them from the reaction system and rinsing them with water.

A simple and environment-friendly method was used to prepare Pt/reduced graphene oxide (Pt/RGO) hybrids. This approach used a redox reaction between Na2PtCl4 and graphene oxide (GO) nanosheets and a subsequent thermal reduction of the material at 200 °C for 24 h in a vacuum oven. In contrast to other methods that use an additional reductant to prepare Pt nanoparticles, the Pt2+ was directly reduced to Pt0 in the GO solution. GO was used as the reducing agent, the stabilizing agent and the carrier. The resulting Pt/RGO hybrid was characterized by X-ray diffraction, thermo-gravimetric analysis, X-ray photoelectron spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. Electrochemical measurements showed that the Pt/RGO hybrids exhibit good activity as catalysts for the electro-oxidation of methanol and ethanol in acid media. Interestingly, the Pt/RGO hybrids showed better electrocatalytic activity and stability for the oxidation of methanol than Pt/C and Pt/RGO hybrids made from other Pt precursors. This indicates that the Pt/RGO hybrids should have great potential applications in direct methanol and ethanol fuel cells.

•Thermosensitive methyl cellulose-based injectable hydrogels were prepared.•The methyl cellulose sol could turn to gel at body temperature.•The composition of the sol affected the gel strength.•They are effective in reducing adhesion formation.Thermosensitive methyl cellulose (MC)-based injectable hydrogels for post-operation anti-adhesion were prepared by integrating polyethylene glycol (PEG), carboxymethyl cellulose (CMC) and chitosan sulfate (CS-SO3) with MC sols. The viscosity of the MC-based sols depended on the sol composition, especially the amount of CMC. The gelation temperature of the sols was tuned by adjusting the concentrations of K+ and other components to obtain an MC-based sol that transformed to a gel at body temperature. The composition of the sol also affected the gel strength. Adding PEG decreased the repulsions between the CMC and CS-SO3 macromolecules and thus increased the gel strength. The efficacy of the MC-based injectable hydrogels as barriers for reducing postsurgical adhesions was evaluated using a rat cecal abrasion model. The PEG and CS-SO3 loaded MC-based injectable hydrogels were effective in reducing adhesion formation and reduced adhesiolysis difficulties.

A facile and efficient approach was developed to synthesize Ag/Cu@Fe3O4 hybrid nanoparticles using L-lysine as a linker. The morphology, composition and crystal structure of the prepared Ag/Cu@Fe3O4 hybrid nanoparticles were characterized by Fourier Transform infrared spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and powder X-ray diffraction. The magnetic properties of the nanoparticles were determined with a vibrating sample magnetometer. The catalytic activity of the Ag/Cu@Fe3O4 hybrid nanoparticles for the reduction of 4-nitrophenol was also studied. The Ag/Cu@Fe3O4 hybrid nanoparticles are efficient catalysts and can easily be recovered from the reaction system because of their magnetic properties. In addition the Ag/Cu@Fe3O4 catalyst had good reusability. This cost effective and recyclable catalyst provides a new material for use in environmental protection applications.

Stable Pickering emulsions were prepared using only graphene oxide (GO) as a stabilizer, and the effects of the type of oil, the sonication time, the GO concentration, the oil/water ratio, and the pH value on the stability, type, and morphology of these emulsions were investigated. In addition, the effects of salt and the extent of GO reduction on emulsion formation and stability were studied and discussed. The average droplet size decreased with sonication time and with GO concentration, and the emulsions tended to achieve good stability at intermediate oil/water ratios and at low pH values. In all solvents, the emulsions were of the oil-in-water type, but interestingly, some water-in-oil-in-water (w/o/w) multiple emulsion droplets were also observed with low GO concentrations, low pH values, high oil/water ratios, high salt concentrations, or moderately reduced GO in the benzyl chloride–water system. A Pickering emulsion stabilized by Ag/GO was also prepared, and its catalytic performance for the reduction of 4-nitrophenol was investigated. This research paves the way for the fabrication of graphene-based functional materials with novel nanostructures and microstructures.Keywords: graphene oxide; hydrophilic properties; multiple emulsion; Pickering emulsion; sonication method;

Reduced graphene oxide coated polyurethane (rGPU) sponges were fabricated by a facile method. The structure and properties of these rGPU sponges were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, and scanning electron microscopy. The rGPU sponges are hydrophobic and oleophilic and show extremely high absorption for organic liquids. For all the organic liquids tested, the absorption capacities were higher than 80 g g–1 and 160 g g–1 (the highest value) was achieved for chloroform. In addition, the absorption capacity of the rGPU sponge did not deteriorate after it was reused 50 times, so the rGPU sponge has excellent recyclability.Keywords: hydrophobic; oil absorption; oleophilic; polyurethane sponge; recyclability; reduced graphene oxide;

Pt–Cu/reduced graphene oxide (Pt–Cu/RGO) hybrids with different Pt/Cu ratios were prepared by the reduction of H2PtCl6 and CuSO4 by NaBH4 in the presence of graphene oxide (GO). The Pt–Cu nanoparticles were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The reduction of GO was verified by ultraviolet–visible absorption spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Compared to Pt/RGO, the Pt–Cu/RGO hybrids have superior electrocatalytic activity and stability for the oxidation of methanol and formic acid. Thus they should have potential applications in direct methanol and formic acid fuel cells.

•Pt/RGO-II and Pt/RGO-IV were prepared via a one step reduction using NaBH4 as reducing agent.•Pt supported on RGO as anode catalyst for DMFCs and DEFCs.•Pt/RGO-II showed enhanced catalytic activity for methanol oxidation than Pt/RGO-IV.•Pt/RGO-II showed enhanced catalytic activity for ethanol oxidation than Pt/RGO-IV.An easy approach for the synthesis of platinum nanoparticles supported on reduced graphene oxide (RGO) was investigated. Pt/RGO-II and Pt/RGO-IV hybrids were prepared using sodium borohydride as the reductant to synchronously reduce graphene oxide (GO) and Na2PtCl4 or H2PtCl6, respectively. The whole synthetic procedure was easily carried out in one pot at room temperature. The Pt/RGO-II and Pt/RGO-IV hybrids were characterized by X-ray diffraction, Raman spectrometry, transmission electron microscopy and X-ray photoelectron spectroscopy. Their electrochemically catalytic activity for direct methanol oxidation was evaluated. Both the Pt/RGO-II and Pt/RGO-IV hybrids show good catalytic activity. However, the Pt/RGO-II hybrids exhibited better electrocatalytic activity and stability for the oxidation of methanol and ethanol than the Pt/RGO-IV hybrids, which may as the PtCl42− has high reduction potential so that it is easy to be reduced. These hybrids show great potential application for use in fuel cells.

•Pt–Cu/RGO was prepared via a one step reduction using NaBH4 as reducing agent.•Pt–Cu supported on RGO as anode catalyst for DMFCs and DEFCs.•Pt–Cu/RGO showed enhanced catalytic activity for methanol oxidation than Pt/RGO.•Pt–Cu/RGO showed enhanced catalytic activity for ethanol oxidation than Pt/RGO.Pt–Cu bimetallic nanoparticles supported on reduced graphene oxide (Pt–Cu/RGO) were synthesized through the simple one-step reduction of H2PtCl6 and CuSO4 in the presence of graphene oxide (GO) at room-temperature. The Pt–Cu/RGO was characterized with UV–vis spectrophotometer, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy and its catalytic behavior for the direct oxidation of methanol was investigated. Compared to Pt/RGO and Pt/C catalysts, Pt–Cu/RGO hybrids exhibited markedly superior catalytic activity for the electrocatalytic oxidation of methanol and ethanol. This improved catalytic activity can be attributed to the dendritic structure of the Pt–Cu bimetallic nanoparticles.

Poly(sodium 4-styrenesulfonate) (PSSS) was grafted onto graphene oxide surfaces by surface-initiated atom transfer radical polymerization using CuBr/1,1,4,7,7-pentamethyldiethylenetriamine as the catalyst and N′,N-dimethyl-formamide as the solvent. X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy were used to verify the grafting of the PSSS chains and the partial reduction of graphene oxide during the grafting process. The PSSS grafted graphene oxide gives a stable aqueous dispersion even after being further reduced with hydrazine hydrate at 90 °C for 24 h. The reduced graphene oxide grafted poly (styrene sulfonic acid) which obtained from PSSS grafted graphene oxide had a good catalytic activity for the synthesis of isoamyl benzoate.Highlights► ATRP-initiator was introduced onto graphene oxide (GO) nanosheets. ► Polyanion PSSS was grated on to GO nanosheets by surface-initiated ATRP. ► GO-g-PSSS could stably dispersed in aqueous solution. ► RGO-g-PSSS showed good catalytic activity for the synthesis of isoamyl benzoate.

An environment-friendly approach to synthesizing reduced graphene oxide (RGO) was developed by using chitosan (CS) as both a reducing and a stabilizing agent. Factors that affect the reduction of graphene oxide (GO), such as the ratio of CS/GO, pH and temperature, were explored to obtain optimum reaction conditions. The RGO was characterized with UV visible absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction spectroscopy, thermo-gravimetric analysis, and X-ray photoelectron spectroscopy and transmission electron microscopy. Analysis shows that CS macromolecules can efficiently reduce GO at a comparatively low temperature and their adsorption onto the RGO nanosheets allows a stable RGO aqueous dispersion to be formed. Since CS is a natural, nontoxic and biodegradable macromolecule, this approach provides a new green method for GO reduction that would facilitate the large scale production of RGO, which has great value for graphene applications. Moreover, CS can reduce GO and AgNO3 (or HAuCl4) in one pot to obtain Ag nanoparticle-RGO hybrids or Au nanoparticle-RGO hybrids that exhibit good electrochemical activity.

Sodium alginate/graphene oxide (NaAlg/GO) fibers were prepared using a wet spinning method. Their structures and properties were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and mechanical strength testing. The incorporation of GO significantly improved the strength of the NaAlg/GO fibers owing to the uniform distribution of the GO nanosheets in the NaAlg matrix. The maximum tensile strength and Young's modulus increased from 0.32 and 1.9 to 0.62 and 4.3 GPa, respectively, at 4 wt% GO loading. The composite fibers had an even higher strength when they were stretched. The tensile strength increased by 43% over the un-stretched fiber, and Young's modulus increased to 9.39 GPa. In aqueous solution, the GO/NaAlg fibers swelled to form hydrogel fibers that are nontoxic to cells which demonstrated the potential applications of the as-spun fibers in wound dressing materials.Highlights► Graphene oxide/sodium alginate (GO/NaAlg) fibers were prepared using a wet spinning method. ► Their tensile strength and Young's modulus reached 0.62 and 4.3 GPa with 4 wt% GO, respectively. ► Young's modulus of the GO/NaAlg fibers could be higher when they were stretched. ► The GO/NaAlg fibers swelled in aqueous solution to form hydrogel fibers that are nontoxic to cells.

Inverse opal hydrogels of polyacrylamide (PAM) with adjustable band gaps (P-IOHspam) were fabricated by changing the molecular weight of polyethylene glycol (PEG), and the amount of PEG and N,N′-methylenebisarcylamide (BIS) in the monomer precursors. After the PEG was removed, mesopores were left in the PAM hydrogels and these caused changes in the band gap of the P-IOHspam. Compared with inverse opal hydrogels of PAM (IOHspam) that were prepared without PEG, the reflection peaks shifted to a longer wavelength which provides a wider usable visible wavelength range. P-IOHspam show rapid shifts in the reflection peak in response to chemicals, such as PEG, glycol, glucose and L-lysine. The shift of the reflection peak is greater for the P-IOHspam made from monomer precursors containing more PEG and for higher molecular weights of PEG. The shifts are caused by changes in two factors: the average refractive index of the P-IOHpam material and the degree of equilibrium swelling of the PAM hydrogel, both of which are sensitive to chemicals. Such sensitive materials could be used as chemical sensors.

Porous graphene oxide foams were prepared by unidirectional freeze-drying technology and used to investigate the reaction between graphene oxide (GO) and SO2. The structure and composition changes of the graphene oxide were monitored by X-ray photoelectron spectrometry (XPS), Raman, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV-vis), and the product of the reaction was analyzed by an EDTA titration. The results show that SO2 was oxidized to SO3 and the GO was reduced. GO not only acts as the oxidant in the reaction, but also as the catalyst to catalyze the reaction of SO2 and O2 to form SO3. This catalytic action is more active in the aqueous GO suspensions than in the foams. The GO foams can adsorb SO2 and convert it to SO3 which then changes to SO42− on contact with water. This offers a new effective method of converting noisome SO2 gas to SO3 at room temperature.

Ordered porous chitosan–gelatin/graphene oxide (CGGO) monoliths with over 97% porosity were prepared by a unidirectional freeze-drying method and used as adsorbents for metal ions. They were characterized by X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. In addition, their water absorption, wet-state stability and compressive strength were measured. The adsorption behavior of the CGGO monoliths and influencing factors such as pH, graphene oxide (GO) concentration, metal ion concentration as well as the effect of ethylenediaminetetraacetic acid (EDTA) were investigated. The incorporation of GO significantly increased the compressive strength of the CGGO monoliths in both their wet and dry states, and changed their porous structure. They exhibited an extremely high adsorbing ability for metal ions, which decreased at low pH, but increased from 20% to 88% upon the addition of EDTA at low pH. The CGGO monoliths have good stability and can be recycled several times with only a slight loss in adsorption ability. In addition, they are biodegradable, non-toxic, efficient and regenerable.Graphical abstractThe SEM photo (a), wet-state stability (b) and effective adsorption ability for metal ions (c) of porous CGGO monoliths.Research highlights► Ordered porous chitosan–gelatin/graphene oxide (CGGO) monoliths have a very high porosity (over 97%) and good stability which should make them a potentially effective adsorbent for metal ions or other chemicals, such as proteins or DNA macromolecules. And the experimental result has proved which they have an extremely high adsorbing ability for metal ions. ► Chitosan–gelatin/graphene oxide monoliths have a very high porosity (over 97%). ► They show high mechanical strength and good stability in aqueous solutions. ► They exhibit an extremely high adsorbing ability for metal ions. ► They can be recycled several times with only a slight loss in adsorption ability.

Actuator materials based on graphene oxide/polyacrylamide (GO/PAM) hydrogels were prepared by in situ polymerization. Their structure and properties were characterized by scanning electron microscopy, X-ray photoelectron spectrometry, thermogravimetric analysis, Fourier transform infrared spectroscopy and mechanical testing. The results indicate that some PAM macromolecules were grafted onto the GO nanosheets, and this led to good dispersion of the GO nanosheets in the composite hydrogels and consequently a significant improvement of their mechanical properties. The compressive strength of the GO/PAM hydrogel loaded with 1 wt% GO increased 6-fold in comparison to that of pure PAM hydrogel. The GO/PAM based hydrogels were responsive to external stimuli such as pH and electric fields.

Porous graphene oxide foams were prepared by unidirectional freeze-drying technology and used to investigate the reaction between graphene oxide (GO) and SO2. The structure and composition changes of the graphene oxide were monitored by X-ray photoelectron spectrometry (XPS), Raman, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV-vis), and the product of the reaction was analyzed by an EDTA titration. The results show that SO2 was oxidized to SO3 and the GO was reduced. GO not only acts as the oxidant in the reaction, but also as the catalyst to catalyze the reaction of SO2 and O2 to form SO3. This catalytic action is more active in the aqueous GO suspensions than in the foams. The GO foams can adsorb SO2 and convert it to SO3 which then changes to SO42− on contact with water. This offers a new effective method of converting noisome SO2 gas to SO3 at room temperature.

Inverse opal hydrogels of polyacrylamide (PAM) with adjustable band gaps (P-IOHspam) were fabricated by changing the molecular weight of polyethylene glycol (PEG), and the amount of PEG and N,N′-methylenebisarcylamide (BIS) in the monomer precursors. After the PEG was removed, mesopores were left in the PAM hydrogels and these caused changes in the band gap of the P-IOHspam. Compared with inverse opal hydrogels of PAM (IOHspam) that were prepared without PEG, the reflection peaks shifted to a longer wavelength which provides a wider usable visible wavelength range. P-IOHspam show rapid shifts in the reflection peak in response to chemicals, such as PEG, glycol, glucose and L-lysine. The shift of the reflection peak is greater for the P-IOHspam made from monomer precursors containing more PEG and for higher molecular weights of PEG. The shifts are caused by changes in two factors: the average refractive index of the P-IOHpam material and the degree of equilibrium swelling of the PAM hydrogel, both of which are sensitive to chemicals. Such sensitive materials could be used as chemical sensors.