Graphene Oxide Content Research Articles

Experimental and theoretical investigation of mechanical and rheological properties of compatibilized XNBR/NR/GO nanocomposites

In this research, nanocomposites based on carboxylated nitrile rubber (XNBR)/natural rubber (NR) with different concentrations of graphene oxide (GO) were prepared by melt mixing method. The role of XNBR-grafted maleic anhydride (XNBR-g-GMA) as a compatibilizer and the effect of GO content on the morphological, mechanical, rheological, and vulcanization properties were evaluated. It was observed that with increasing the concentration of GO, the scorch and vulcanization time decreased, while the torque of the samples increased. Morphological studies illustrated that by raising the concentration of GO in the presence of a compatibilizer, the fracture surface of nanocomposites became rougher and the average size of dispersed phase decreased. In addition, the presence of XNBR-g-GMA compatibilizer improved the uniform dispersion of GO within the XNBR/XNBR-g-GMA/NR matrix. The mechanical properties of nanocomposites showed the best results for XNBR/NR with a ratio of 75/25. Theoretical studies on the mechanical and rheological properties of nanocomposites performed by Mori-Tanaka and Carreau-Yasuda models and illustrated a good agreement with experimental data.

Polycaprolactone/Testicular Extracellular Matrix/Graphene Oxide-Based Electrospun Tubular Scaffolds for Reproductive Medicine: Biomimetic Architecture of Seminiferous Tubules.

Numerous scaffolds are developed in the field of testicular bioengineering. However, effectively replicating the spatial characteristics of native tissue, poses a challenge in maintaining the requisite cellular arrangement essential for spermatogenesis. In order to mimic the structural properties of seminiferous tubules, the objective is to fabricate a biocompatible tubular scaffold. Following the decellularization process of the testicular tissue, validation of cellular remnants' elimination from the specimens is conducted using 4',6-diamidino-2-phenylindole staining, hematoxylin and eosin staining, and DNA content analysis. The presence of extracellular matrix (ECM) components is confirmed through Alcian blue, Orcein, and Masson's trichrome staining techniques. The electrospinning technique is employed to synthesize the scaffolds using polycaprolactone (PCL), extracted ECM, and varying concentrations of graphene oxide (GO) (0.5%, 1%, and 2%). Subsequently, comprehensive evaluations are performed to assess the properties of the synthetic scaffolds. These evaluations encompass Fourier-transform infrared spectroscopy, scanning electron microscopy imaging, scaffold degradation testing, mechanical behavior analysis, methylthiazolyldiphenyl-tetrazolium bromide assay, and in vivo biocompatibility assessment. The PCL/decellularized extracellular matrix with 0.5% GO formulation exhibits superior fiber morphology and enhanced mechanical properties, and outperforms other groups in terms of in vitro biocompatibility. Consequently, these scaffolds present a viable option for implementation in "in vitro spermatogenesis" procedures, holding promise for future sperm production from spermatogonial cells.

Tuning the electron–phonon interaction via exploring the interrelation between Urbach energy and fano-type asymmetric raman line shape in GO-hBN nanocomposites

Hexagonal boron nitride (hBN), having an in-plane hexagonal structure in the sp2 arrangement of atoms, proclaims structural similarity with graphene with only a small lattice mismatch. Despite having nearly identical atomic arrangements and exhibiting almost identical properties, the electronic structures of the two materials are fundamentally different. Considering the aforementioned condition, a new hybrid material with enhanced properties can be evolved by combining both materials. This experiment involves liquid phase exfoliation of hBN and two-dimensional nanocomposites of GO-hBN with varying hBN and graphene oxide (GO) ratios. The optical and vibrational studies conducted using UV–vis absorption and Raman spectroscopic analysis report the tuning of electron–phonon interaction (EPI) in the GO-hBN nanocomposite as a function of GO content (%). This interaction depends on disorder-induced electronic and vibrational modifications addressed by Urbach energy (E u ) and asymmetry parameter (q), respectively. The EPI contribution to the induced disorders estimated from UV–vis absorption spectra is represented as EPI strength (E e–p ) and its impact observed in Raman phonon modes is quantified as an asymmetry parameter (q). The inverse of the asymmetry parameter is related to E e–p , as E e–p ∼ 1/|q|. Here in this article, a linear relationship has been established between E u and the proportional parameter (k), where k is determined as the ratio of the intensity of specific Raman mode (I) and q 2, explaining the disorders’ effect on Raman line shape. Thus a correlation between Urbach energy and the asymmetry parameter of Raman mode confirms the tuning of EPI with GO content (%) in GO-hBN nanocomposite.

Polyvinyl Butyral/Graphene Oxide Composite Coating for Properties Improvement

In this paper, polyvinyl butyral (PVB) composite coating was prepared with graphene oxide (GO) for improving mechanical properties, corrosion protection, thermal oxidation stability. Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscopy (FESEM),... were used to examine the results. Presence of GO in composite coating was characterized by FT-IR. Corrosion protection of PVB coating containing GO was determined with salt mist testing with 4 cycles in 5% NaCl, each cycle included 2 hours spraying at 35±2 oC , kept in humidity condition for 7 days at 40± 2 oC with relative humidity of 93 ± 2%. Effects of GO on adhesion, flexibility, impact resistance, relative hardness and thermal oxidation stability of PVB composite coatings were also investigated. Results showed that GO content in PVB composite coating of 1.5 wt.% had significantly enhanced mechanical properties, corrosion resistance of PVB composite coating. Thermal oxidation resistance of PVB composite coating with 1.5 wt.% of GO was much higher than that of PVB composite coating without GO.

Bend‐Resistant and Energy‐Friendly GO‐PVA/PVA Polymer Electret Synaptic Transistors for Neuromorphic Computations

AbstractPolymer electret synaptic transistor is a promising three‐terminal artificial synaptic device. In this work, the electrical characteristics of the composite insulator and transistor are enhanced by modulating the concentration of the 2D nanofiller graphene oxide (GO) and the stacked film structure based on a polyvinyl alcohol (PVA) matrix. The GO‐PVA/PVA polymer electret synaptic transistors before and after dynamic/static bending exhibit typical synaptic characteristics, including short‐term plasticity, long‐term plasticity, pair‐pulse facilitation, spike‐timing‐dependent plasticity, and “learning–forgetting–relearning” features. Importantly, the device exhibits good cycling stability, uniformity and linearity in the potentiation‐depression cycling test, which is beneficial for improving the accuracy of neuromorphic computations. Also, it shows extremely low energy consumption (≈0.32 fJ). The recognition accuracy of images is simulated based on the constructed artificial neural network, which achieves 86.8% for the MNIST dataset. In addition, the devices maintain high recognition accuracy after dynamic/static bending, indicating that the devices are extremely bend‐resistant. The GO‐PVA/PVA polymer electret synaptic transistor is expected to be a potential candidate for neuromorphic computations and electronic skin.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Bionanocomposites with Crystalline Nanocellulose and Graphene Oxide: Experimental Results and Support Vector Machine Modeling.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biodegradable and biocompatible bacterial copolymer used in the biomedical and food industries. However, it displays low stiffness and strength for certain applications. This issue can be solved via reinforcement with nanofillers. In this work, PHBHHx-based bionanocomposites reinforced with different loadings of crystalline nanocellulose (CNC) and graphene oxide (GO) were developed by a green and straightforward solution casting technique. Their crystalline nature and surface topography were explored via X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively, their composition was corroborated via Fourier-transformed infrared spectroscopy (FTIR), and their crystallization and melting behavior were determined via differential scanning calorimetry (DSC). The nanofillers had a nucleating role, raising the crystallization temperature of the polymer, whilst hardly any changes were found in the melting temperature. Further, significant enhancements in the stiffness, strength, and thermal stability of the PHBHHx matrix were observed with the incorporation of both nanofillers, which was attributed to a synergic effect. The mechanical properties for various concentrations of CNC and GO were accurately predicted using a machine learning (ML) model in the form of a support vector machine (SVM). The model performance was evaluated in terms of the mean absolute error (MAE), the mean square error (MSE), and the correlation coefficient (R2). These bio-based nanocomposites are a valuable alternative to conventional petroleum-based synthetic polymeric materials used nowadays for biomedicine and food packaging applications.

Interfacial interaction of graphene oxide with montmorillonite in tailoring the structure and proton transport phenomena of alginate/PVA membrane for DMFC applications

AbstractPolymer electrolyte membrane that has high proton conductivity and low methanol permeability are necessary for direct methanol fuel cells (DMFCs). A sodium alginate (SA)/polyvinyl alcohol (PVA)/montmorillonite (MMT)/graphene oxide (GO) quaternary composite membrane was effectively developed in this study. The homogeneous distribution of MMT and GO nanosheets in the SA/PVA/MMT/GO composite membrane was exhibited by scanning electron microscopy (SEM). Intriguingly, it has been established that the SA/PVA membrane contains chemical crosslinks between MMT and GO, which significantly contribute to the rise in proton conductivity. The SA/PVA/MMT/GO hybrid membrane has minimum loss modulus of 47.91% and storage modulus of up to 2.689 × 109 Pa, which are 3.8 times greater than those of SA/PVA‐MMT membrane without GO. This value indicates the viscosity and elasticity of the produced membrane. The quaternary composite membrane also exhibits outstanding oxidative stability and methanol barrier characteristics. The methanol permeability of SA/PVA/MMT/GO films 0.524 × 10−9 cm2 s−1, with methanol absorption as low as 9.72%. The best membrane performs at a high‐power density (1.761 mW/cm2) of DMFC at a GO content of 1.3 wt% because it obtains the maximum selectivity value (7.0529 × 106 S scm−3). Future commercial membranes may be replaced by the innovative quaternary membrane created in this work, which has significant potential.

Ultrasonic Spray Deposited CdS-GO Composite Films for Solar Cell Applications

In the present study, the synthesis and characterization of cadmium sulfide (CdS) and graphene oxide (GO) composite films are investigated. These films have the potential to be utilized in solar cell applications due to their unique optical and electric properties. A chemical bath deposition was used to prepare the CdS thin films, while the hammer method was used to synthesize GO sheets. In this comparative study, spray deposition was used to prepare CdS-GO composite films with different ratios of CdS to GO. The spray deposition method used in this study offers a simple and cost-effective way to prepare large-area films for practical applications. The structural, and optical, properties of the composite films were characterized using X-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy measurements. The results show that the CdS-GO composite films exhibit enhanced optical properties as compared to the pure CdS films. The band gap energy of the composite films decreased with increasing GO content, indicating improved optical properties. These findings suggest that CdS-GO composite films have the potential for use in solar cell applications. I-V characteristics were obtained using a solar cell tester kit to analyse the applications of fabricated conducting films in the field of solar cells.

Exploring the Influence of Chemical Conditions on Nanoparticle Graphene Oxide Adsorption onto Clay Minerals.

High concentrations of graphene oxide (GO), a nanoparticle substance with rapid manufacturing development, have the ability to penetrate the soil surface down to the mineral-rich subsurface layers. The destiny and distribution of such an unusual sort of nanomaterial in the environment must therefore be fully understood. However, the way the chemistry of solutions impacts GO nanoparticle adsorption on clay minerals is still unclear. Here, the adsorption of GO on clay minerals (e.g., bentonite and kaolinite) was tested under various chemical conditions (e.g., GO concentration, soil pH, and cation valence). Non-linear Langmuir and Freundlich models have been applied to describe the adsorption isotherm by comparing the amount of adsorbed GO nanoparticle to the concentration at the equilibrium of the solution. Our results showed fondness for GO in bentonite and kaolinite under similar conditions, but the GO nanoparticle adsorption with bentonite was superior to kaolinite, mainly due to its higher surface area and surface charge. We also found that increasing the ionic strength and decreasing the pH increased the adsorption of GO nanoparticles to bentonite and kaolinite, mainly due to the interaction between these clay minerals and GO nanoparticles' surface oxygen functional groups. Experimental data fit well to the non-linear pseudo-second-order kinetic model of Freundlich. The model of the Freundlich isotherm was more fitting at a lower pH and higher ionic strength in the bentonite soil while the lowest R2 value of the Freundlich model was recorded at a higher pH and lower ionic strength in the kaolinite soil. These results improve our understanding of GO behavior in soils by revealing environmental factors influencing GO nanoparticle movement and transmission towards groundwater.

Evaluation of the Antibacterial Effect of the Prepared Graphene Oxide Nanosheets

Because of its exceptional chemical, physical, and biological features, graphene oxide (GO) has gained great attention. The Simplified Hammer's method was used in this study to synthesize GO nanosheets, which were then characterized by UV-Vis, SEM, FTIR spectroscopy, and XRD analysis. GO's UV-Vis peak of absorption was at 230 nm. A peak of diffraction at 2θ= 10.75° was found in the XRD examination, equivalent to around 0.82 nm spacing among layers. In the FTIR spectra, characteristic peaks associated with oxygen functional groups of GO were identified. In SEM pictures, GO is made up of crumpled thin nanosheets. The diffusion in agar well procedure was applied to investigate the effect of as-prepared GO nanosheets against gram-negative "Pseudomonas aeruginosa, Salmonella typhi" and gram-positive "Enterococcus sp., Kocuria sp." Different concentrations of GO demonstrated potent antibacterial activity, with higher efficacy against gram-positive bacteria. Keywords: Graphene Oxide, Nanosheets, Antibacterial effect, XRD, SEM, FTIR.

Multigenerational Effects of Graphene Oxide Nanoparticles on Acheta domesticus DNA Stability.

The use of nanoparticles like graphene oxide (GO) in nanocomposite industries is growing very fast. There is a strong concern that GO can enter the environment and become nanopollutatnt. Environmental pollutants' exposure usually relates to low concentrations but may last for a long time and impact following generations. Attention should be paid to the effects of nanoparticles, especially on the DNA stability passed on to the offspring. We investigated the multigenerational effects on two strains (wild and long-lived) of house cricket intoxicated with low GO concentrations over five generations, followed by one recovery generation. Our investigation focused on oxidative stress parameters, specifically AP sites (apurinic/apyrimidinic sites) and 8-OHdG (8-hydroxy-2'-deoxyguanosine), and examined the global DNA methylation pattern. Five intoxicated generations were able to overcome the oxidative stress, showing that relatively low doses of GO have a moderate effect on the house cricket (8-OHdG and AP sites). The last recovery generation that experienced a transition from contaminated to uncontaminated food presented greater DNA damage. The pattern of DNA methylation was comparable in every generation, suggesting that other epigenetic mechanisms might be involved.

Covalently modified Kevlar fabric incorporating graphene oxide with enhanced antibacterial properties and preserved strength.

This work describes a multi-step modification process for the covalent transformation of Kevlar fabric en route the incorporation of graphene oxide (GO) nanosheets. Spectroscopic, thermal and microscopy imgaing techniques have been employed to follow step-by-step the modification of Kevlar and the formation of the corresponding Kevlar-GO hybrid fabric. The level of Kevlar's functionalization can be controled with the nitration time, the first reactionin the multi-sequence organic transformations, for obtaining the hybrid fabricwith a content of GO up to 30%. Most importantly, the covalent post-modification of Kevlar does not occur in the expense of the other otherwise excellent mechanical properties of the fabric. Under optimal conditions, theKevlar-GO hybrid fabric shows a 20% enhancement of the ultimate strengh. Notably, when the Kevlar-GO hybrid fabric exposed to cyanobacterialSynechococcusthe bacteria growth was fully inhibited. Overall, the covalently modified fabric demonstrated significant antibacterial behavior, excellent strength and stability under common processes. Due to its simplicity, the methodology presented in this work not only promises to result in a standard procedure to functionalize themerunits of Kevlar witha variety of chemicals and nanomaterials but it can be also extended for the modification and hybridization of other fabrics.

Effects of Graphene Oxide on the Properties of Engineered Cementitious Composites: Multi-Objective Optimization Technique Using RSM

Despite the excellent ductility and energy absorption properties of engineered cementitious composites (ECCs), a low modulus of elasticity and excessive drying shrinkage remain some of its major disadvantages. With the current trend in the application of nanotechnology in cementitious composites research, the effect of graphene oxide (GO) on the properties of ECCs is yet to be fully investigated, despite its promising results in ordinary cement paste, mortar, and concrete. ECCs need extensive material tailoring to provide the required mechanical characteristics and controlled fracture size with strain-hardening behavior. Striking a balance between these crucial hardened aspects of ECC without compromising any desired properties is a challenge. Hence, the main aim of the study reported in this paper is to use the response surface methodology (RSM) multi-objective optimization technique to identify an appropriate GO content via the weight of cement and also the volume fraction of polyvinyl alcohol (PVA) fiber as input variables that positively impact ECCs’ properties. Using RSM’s central composite design (CCD), 13 mixtures of various combinations of the variables (GO: 0.05%, 0.065%, 0.08%; PVA: 1%, 1.5%, 2%) were developed. Six responses were studied, including compressive strength, direct tensile strength, tensile capacity, flexural strength, modulus of elasticity, Poisson’s ratio, and drying shrinkage. Moreover, the microstructural properties of the composites were assessed using field-emission scanning electron microscopy (FESEM) and mercury intrusion porosimetry (MIP). The outcomes revealed that all the properties of ECCs were significantly enhanced by adding an optimum amount of 0.05% GO and 1–1.5% PVA fiber volume fractions. A maximum increase in 30%, 35%, 49%, and 33.9% in the compressive strength, direct tensile strength, flexural strength, and modulus of elasticity, respectively, of the mixes with 0.05% GO addition was recorded. It is demonstrated that the use of 0.05% GO as a nanoscale particle can provide good outputs for the construction industry.

Effective reinforcement of plasticized starch by the incorporation of graphene, graphene oxide and reduced graphene oxide

Plasticized starch (PLS) nanocomposite films using glycerol and reinforced with graphene (G) and graphene oxide (GO) were prepared by solvent casting procedure. On one hand, the influence of adding different G contents into the PLS matrix was analyzed. In order to improve the stability of G nanoflakes in water, Salvia extracts were added as surfactants. The resulting nanocomposites presented improved mechanical properties. A maximum increase of 287 % in Young's modulus and 57 % in tensile strength was achieved for nanocomposites with 5 wt% of G. However, it seemed that Salvia acted as co-plasticizer for the PLS. Moreover, the addition of the highest G content led to an improvement of the electrical conductivity close to 5 × 10−6 S/m compared to the matrix.On the other hand, GO was also incorporated as nanofiller to prepare nanocomposites. Thus, the effect of increasing the GO content in the final behavior of the PLS nanocomposites was evaluated. The characterization of GO containing PLS nanocomposites showed that strong starch/GO interactions and a good dispersion of the nanofiller were achieved. Moreover, the acidic treatment applied for the reduction of the GO was found to be effective, since the electrical conductivity was 150 times bigger than its G containing counterpart.

A highly sensitive paper-based chipless RFID humidity sensor based on graphene oxide

In this paper, a highly sensitive paper-based humidity sensor is designed and fabricated to overcome the typically low sensitivity and small quality factor of paper-based chipless radio-frequency identification (RFID) humidity sensors. A toroidal inductor-interdigitated electrodes (IDE) capacitor is used as the resonator structure of the new sensor, and the structural parameters of the sensor are optimized using the software of high frequency structure simulator (HFSS) to improve the quality factor. Three paper-based sensor samples were fabricated via screen printing using regular printing paper, Kodak photo paper, and double-sided copper-coated paper as the substrate. In addition, the resonance characteristics, sensitivity, recovery characteristics, stability and other sensor performances were tested. The results show that the sensitivity of the copper-coated-paper-based sensor is significantly better than the two other paper-based sensors. The simulation and test results of the moisture-sensitive characteristics are consistent for graphene oxide (GO) films, which were prepared using the spray method on the surface of the copper-coated-paper-based sensor with mass concentrations of 1 mg/mL, 2 mg/mL, and 5 mg/mL. This indicates that GO films can significantly improve sensor sensitivity when combined with paper-based moisture sensing. Furthermore, the sensitivity increases with increasing GO concentration, the 5 mg/mL GO sensor show a sensitivity of 6.25 MHz/%RH and a range of 60% RH-90% RH. The 1 mg/mL GO humidity sensor shows good recovery characteristics (92.4% recovery). Based on the presence of hydrophilic functional groups in the GO material, a moisture sensing mechanism that GO could improve the sensitivity of the sensor is analyzed.

Effect of rGO concentration on the microstructure and friction behavior of co-doped diamond-like carbon (Ni/N/rGO-DLC) films

A kind of wear-resistant and lubricated Ni/N/rGO-DLC films are deposited on the surface of Ti-6Al-4V(TC4) alloy substrate by an integrative method involving pulsed electrodeposition and liquid-phase electrodeposition with various rGO (reduced graphene oxide) concentration. The growth mechanism of the film and the formation of protrusions and gully structures on the surface of the film are investigated. Furthermore, the mechanism of the effect of rGO concentration on the dispersion stability of the electrolytic system is explored. The results reveal that the Ni/N/rGO-DLC films at 0.07 g·L−1 rGO exhibit a uniform and dense structure. rGO particles are uniformly incorporated into the carbon-based films and tend to deposit perpendicular on the substrate. Simultaneously, the highest micro-indentation hardness, the lowest coefficient of friction and wear loss are obtained as 591.88 HV, 0.072 and 1.20 × 10−4 kg·m−1 of film with 0.07 g·L−1 rGO, which are principally attributed to the synergistic effect of rGO particles and amorphous carbon matrix in improving the mechanical properties of Ni/N/rGO-DLC films.

Additive Manufacturing of Cu Using Graphene-Oxide-Treated Powder.

Additive manufacturing of Cu is interesting for many applications where high thermal and electric conductivity are required. A problem with printing of Cu with a laser-based process is the high reflectance of the powder for near-infrared wavelengths making it difficult to print components with a high density. In this study, we have investigated laser bed fusion (L-PBF) of Cu using graphene oxide (GO)-coated powder. The powder particles were coated in a simple wet-chemical process using electrostatic attractions between the GO and the powder surface. The coated powder exhibited a reduced reflectivity, which improved the printability and increased the densities from ~90% for uncoated powder to 99.8% using 0.1 wt% GO and a laser power of 500 W. The coated Cu powders showed a tendency for balling using laser powers below 400 W, and increasing the GO concentration from 0.1 to 0.3 wt.% showed an increase in spattering and reduced density. Graphene-like sheet structures could be observed in the printed parts using scanning electron microscopy (SEM). Carbon-filled inclusions with sizes ranging from 10-200 nm could also be observed in the printed parts using transmission electron microscopy (TEM). The GO treatment yielded parts with higher hardness (75.7 HV) and electrical conductivity (77.8% IACS) compared to the parts printed with reference Cu powder.

Experimental Investigation of Mechanical Properties of Clay–Cement Slurry Containing Graphene Oxide

As a widely used material in underground engineering, clay–cement slurry grouting is known for its initial poor anti-seepage and filtration capacity, the low strength of the resulting stone body, and its tendency towards brittle failure. To explore efficient and environmentally friendly grouting materials, industrial-grade graphene oxide (GO) was incorporated into a clay–cement slurry to create a new type of slurry called a GO composite. These GO composites were then utilized to reinforce fractured formations. Uniaxial compression tests, shear strength tests, permeability tests, and electron microscopy scans were conducted to investigate the strength, permeability, and microscopic features of the GO composite-reinforced fractured formations. Furthermore, the optimization effect and application prospects of graphene oxide on clay–cement slurry materials were evaluated. The experimental results demonstrated that the modified slurry effectively improved the compressive strength (increased by 7.2% to 32.5%) and shear strength (increased by 28.6% to 105.3%) of consolidated fractured gravel. By conducting orthogonal experiments with range analysis, variance analysis, and multiple regression analysis, it was shown that there was a strong correlation between the consolidated body and three factors influencing the permeability coefficient. Among these factors, the OPC content had the most significant impact on the permeability coefficient, followed by the GO content. Graphene oxide was found to promote cement hydration reactions, guide the growth of hydration products on the surface of graphene oxide nanosheets, optimize the pore structure in grouting materials, and reduce microcracks between the slurry and the fractured gravel interface. Electron microscopy characterization and fractal analysis revealed that the addition of graphene oxide effectively reduced the degree of microdamage during the sample’s failure process. This ensured the integrity of the sample during the unstable failure process, enhanced the material’s toughness, and improved its ability to resist loads.

Physical mixing of piezo-electrocatalysts and graphene oxide to promote CO2 conversion

Piezo-electrocatalytic CO2 reduction reaction (PECRR) technique has been verified as an effective CO2-to-fuel conversion strategy by exploiting and utilizing the widely distributed mechanical energy in nature, e.g., blue energy. The facile large-scale preparation of high-performance and low-cost piezo-electrocatalysts is therefore highly desired but challenging. Herein, a method of physical mixing of piezo-electrocatalysts and earth-abundant carbon-based materials is proposed to address the above issue, and we verified this method with typical piezoelectric BaTiO3 and graphene oxide (GO) as a demonstration. With an optimized GO concentration, the BaTiO3 shows a CO yield of 134.4 μmol g−1 h−1 which is about 45.3 % higher than that of pristine BaTiO3. The mechanisms for the enhancement are revealed via boosted piezo-carrier dynamics and charge transfer from BaTiO3 to GO as well as enhanced intrinsic activity. Furthermore, physical mixing of GO is extended to other piezo-electrocatalysts (MoS2, ZnO, ZnS, CdS, Bi2WO6), from which it is found that their performance is improved compared to the counterpart of those without GO. This work suggests that the physical mixing GO is a universal method to improve PECRR performance and may be a decent candidate approach for large-scale preparation of high-performance and low-cost piezo-electrocatalysts in future.

Advanced toluene/n-heptane separation by pervaporation: investigating the potential of graphene oxide (GO)/PVA mixed matrix membrane

BackgroundThe separation and purification of aromatic/aliphatic hydrocarbon mixtures from petroleum feedstocks is a significant industrial undertaking that poses several challenges. This task is commonly encountered during the production of ultralow-sulfur gasoline and naphtha reforming processes, both of which are critical for various industries. Recently, membrane pervaporation for separating aromatic/aliphatic mixtures is regarded as a promising option compared to conventional methods due to its energy efficiency. MethodThe preparation of a cross-linked polyvinyl alcohol (PVA) membrane with varying molecular weights, is aimed at effectively separating toluene/n-heptane. To further enhance the separation efficiency, mixed matrix membranes (MMMs) were fabricated by incorporating graphene oxide (GO) at different loadings. Significant findingsThe PVA membrane with a molecular weight of 130,000 was utilized as the polymer phase, as it exhibited a permeation flux of 24.8 g/m2h and a separation factor of 5.5. Increasing the GO loading from 0.5 to 1.5 wt% increased total flux; however, further increments in GO content led to a decrease in flux. Notably, the PVA-1.5GO sample demonstrated optimum performance, with a total permeation flux of 30.6 g/m2h, separation factor of 11.9. For this sample, pervaporation separation index (PSI) of 333.54 was obtained, indicating a 199% increase compared to that of pure PVA membrane (111.4).