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A direct methanol fuel cell (DMFC) is one prominent alternative energy technology. However, there are many problems that prevent the commercialization of DMFC, such as methanol crossover, low power density, and degradation of the membrane. To resolve these issues, functionalized graphene oxide (GO) and calcium hydroxy phosphate (CHP) were incorporated into the Nafion membrane to make a composite membrane. The content of the CHP was varied to determine and further investigation involved spraying the same amount of CHP onto the Nafion membrane to compare with the composite membrane. The fillers were characterized using Fourier-transform infrared spectroscopy and X-ray Powder Diffraction. The ex-situ tests investigated water uptake, solubility, and chemical degradation, while the in-situ tests investigated electrochemical impedance (EIS), methanol permeability, fuel cell performance, and durability. Adding both 1 wt% of CHP and 0.05 wt% functionalized GO into the Nafion membrane, resulting in a 1.86-fold higher durability than that of recast Nafion. In addition, the maximum power density of the composite membrane was 1.34-fold higher (75.41 mW/cm2) than that of the recast Nafion (56.11 mW/cm2) at 1 M methanol and 70 °C. At 2 M methanol and 70 °C, the maximum power density of the composite membrane increased to 80.19 mW/cm2 but then decreased to 46.00 mW/cm2 when the methanol feed increased to 4 M, due to the large amount of methanol crossover. • 1 wt% CHP functionalized 0.05 wt% GO/Nafion was used for DMFC. • The composite membrane was 1.86-fold higher durability than that of recast Nafion. • Power density was 1.34-fold higher than that of Nafion at 1 M methanol and 70 °C. • At 2 M methanol and 70 °C was the optimum condition for DMFC. [ABSTRACT FROM AUTHOR]

Abstract Hydrophobic polyvinylidene fluoride (PVDF) membranes have been successfully used in membrane distillation (MD) for desalination applications; however, there is still room for performance enhancements both regarding water flux and salt rejection. In this work, reduced graphene oxide (rGO) nanoplatelets with different degrees of reduction (36%, 58%, 65 and 69% removal of oxygen, as characterized by XPS) were incorporated as fillers in PVDF matrices in order to evaluate the effect of the oxygen content of the fillers in the MD performance. UV–Vis and Raman spectroscopies were also used to characterize the fabricated rGO. Changes in morphology of the prepared mixed matrix membranes (MMMs) were assessed via scanning electron microscopy (SEM) and were related to the increased hydrophilicity and viscosity of the casting solutions when fillers were added. MMMs containing 0.5 wt% rGO with an optimum degree of reduction of 58% exhibited an improved MD performance, with fluxes of ~7.0 L m−2 h−1 (LMH), representing an enhancement of ~169% in comparison with the plain PVDF membrane, without compromising salt rejection (>99.99%). Continuous testing for up to 96 h showed a stable performance of the developed MMMs, without compromising the quality of the permeate. Graphical abstract Unlabelled Image Highlights • Reduced graphene oxide (rGO) nanosheets with different degrees of reduction were synthesized. • Mixed matrix membranes (MMMs) containing rGO nanosheets in PVDF were prepared. • The effect of reduction degree on membrane distillation performance was investigated. • The MMMs showed increased water flux and high salt rejection. [ABSTRACT FROM AUTHOR]

Abstract Thin film nanocomposite (TFN) membranes of polymer of intrinsic microporosity PIM-1 incorporating graphene oxide (GO) nanosheets of different sizes and chemistries are presented. These membranes show an improved separation performance for the recovery of n -butanol from aqueous solutions through pervaporation; an improvement of ca. a third of the value achieved for pristine PIM-1 thin films is obtained for TFN membranes filled with nanometer-sized reduced octyl-functionalized GO. In addition, these nanometer-sized fillers lead to a maximum increase in total flux of approximately 40%. The thickness of the supported films is in the range 1–1.5 µm, and fillers used are micrometer- and nanometer-sized alkyl-functionalized GO nanosheets and their chemically reduced counterparts. As evidenced by a superior overall membrane performance, the interfacial interaction between the filler and the polymer matrix is enhanced for those whose lateral size is in the nanometer range. Moreover, an enhancement in the separation performance and productivity of such membranes is observed for higher operating temperatures and higher contents of n -butanol in the feed. Graphical abstract fx1 Highlights • PIM-1/alkyl-functionalized graphene thin film nanocomposite (TFN) membranes were prepared. • TFN membranes were tested for n-butanol recovery from aqueous solutions via pervaporation. • The addition of nano-sized fillers improved the separation performance of PIM-1 thin film membranes. • Nano-sized fillers enhanced the total flux up to approximately 40%. [ABSTRACT FROM AUTHOR]

Air gap membrane distillation (AGMD) is an emerging desalination technology with the potential to meet the challenge of global water scarcity due to its low cost and high thermal efficiency compared to other processes. However, despite the potential of AGMD, a lack of appropriate membranes limits its commercial application. Therefore, this study was focussed on the fabrication of high flux, robust membranes for the purification of artificial sea water by incorporating graphene oxide functionalized with 3-(aminopropyl)triethoxysilane (APTS) into PVDF polymer solutions. Successful functionalisation of GO with APTS was confirmed with XPS and FTIR. It was shown that the addition of GO and GO-APTS enhanced the permeate flux by 52% and 86%, respectively, compared to pure PVDF. The best performing membrane contained 0.3 wt% GO-APTS (with respect to PVDF) and had a flux of 6.2 LMH (L m −2 h −1 ) whilst maintaining perfect salt rejection (>99.9%). These improvements were attributed to increased surface and bulk porosity, larger mean pore size and hydrophilic interactions owing to the functional groups of GO and GO-APTS. These membranes are evidence of the potential that GO and related materials have as nanocomposite fillers in high performance desalination membranes. [ABSTRACT FROM AUTHOR]

In this work, graphene oxide (GO) was combined with polyethersulfone (PES) to form mixed matrix membranes (MMMs) for ultrafiltration of aqueous solutions. Also, the effect of adding various pore formers (poly(vinylpyrrolidinone (PVP), reverse triblock Pluronic (P31R1), and poloxamine Tetronic (T904)) to the dope solution was investigated. The prepared MMMs were characterised using various techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy. It was found that the incorporation of 0.5 wt% of GO increased the flux from 2 to 13 L m −2 h −1 (LMH) and the rejection of bovine serum albumin (BSA) from 89.2 to 97% compared to benchmark PES membranes. SEM analysis revealed the increased pore size and porosity of the GO modified membranes, which contributed to the increased flux. The addition of pore formers further increased the flux compared to pure PES and also displayed synergistic effects with GO. The combination of T904 with 0.3 wt% GO increased the water flux significantly from 2 to 245 LMH and increased the rejection of acridine orange (from 40.5 to 48.4%) and BSA (from 89.6 to 93.3%), respectively. Also, fouling properties of the membranes were investigated with the parameters: flux recovery ratio ( FRR ), total flux decline ratio ( R t ), reversible flux decline ratio ( R r ), and irreversible flux decline ratio ( R ir ), and improved anti-fouling properties were obtained with the addition of GO. This work shows the promise of GO as a performance-enhancing additive in MMMs for wastewater treatment. [ABSTRACT FROM AUTHOR]

Reduced electrochemically exfoliated graphene oxide (rEGO) is combined with carbon black (CB) as a hybrid support material to improve platinum (Pt) catalyst electrochemical activity and durability. Pt/rEGO 2 -CB 3 (rEGO/CB ratio 2/3) retains 71% of initial electrochemical surface area (ECSA) and maintains higher oxygen reduction reaction (ORR) activity compared to Pt/CB after 30000 cycles of the accelerated stress test (AST). In addition, Pt/rEGO 2 -CB 3 shows a 1.8 times improvement in the hydrogen fuel cell performance compared with Pt/CB and is more stable after 24 h at a continuous 0.60 V. The Pt/rEGO 2 -CB 3 promotes the 4e− reaction pathway demonstrated by linear sweep voltammetry (LSV), which leads to greater ORR activity. In addition, the combination of rEGO and CB leads to both enhanced transport properties and improved stability. The Pt particles on both CB and rEGO are less likely to agglomerate in the composite support than in either of the two carbon supports when used alone. Pt supported on a hybrid support combining electrochemically exfoliated graphene oxide and carbon black (Pt/rEGO 2 -CB 3) achieved 1.8 times improved performance and higher durability compared with Pt supported on a single carbon black (Pt/CB). [Display omitted] • Nano-sized graphene oxide were prepared by electrochemical exfoliation method. • The structured support combining EGO and carbon black relieves mass transfer issue. • Pt/rEGO 2 -CB 3 significantly improves PEMFC performance with high durability. [ABSTRACT FROM AUTHOR]

• Polyethersulfone (PES) membranes comprising graphene oxide (GO) were prepared. • 3-aminopropyltriethoxysilane functionalized GO (APTS-GO) fillers were added to PES. • Better rejections for dyes and salts were obtained for the mixed matrix membranes (MMMs). • A 6-fold increase in water flux was achieved by adding pore formers along APTS-GO. • A reduction in fouling propensity is obtained for membranes containing APTS-GO. In this study, graphene oxide (GO) functionalized with 3-aminopropyltriethoxysilane (APTS) was incorporated into polyethersulfone (PES) membranes prepared by non-solvent induced phase inversion (NIPS). This resulted in increased rejections of protein bovine serum albumin (BSA), divalent salts (MgSO 4) and low-molecular weight dyes (sunset yellow and acridine orange). The structural properties of the prepared mixed matrix membranes (MMMs) as well as pure PES control membranes were investigated through scanning electron microscopy (SEM), atomic force microscopy (AFM), specific surface area, zeta potential and contact angle. It was found that the introduction of APTS-GO fillers in the polymer matrix made the membranes' application range move from ultrafiltration (UF) for pure PES membranes to nanofiltration (NF) for MMMs with a molecular weight cut off (MWCO) of ~1000 Da. Furthermore, membranes prepared by using only 0.1 wt% APTS-GO in combination with 1 wt% of pore-forming agent polyvinylpyrrolidone (PVP 40 K) in the casting solution exhibited high water permeance values of 9.9 LMHbar (L m−2 h−1 bar−1) at low operating pressures of 4 bar and rejections of dyes and BSA > 95%. In addition, improved anti-fouling properties and tensile strength values were obtained when incorporating the functionalized GO. [ABSTRACT FROM AUTHOR]