C, Volume 2, Issue 2 (June 2016) – 8 articles

Within this short communication article, we consider the value that closer and earlier collaboration between engineers and social scientists could offer the research, development, demonstration and deployment (RDD & D) of industrial technologies. We consider perspectives taken from both the social sciences and engineering in order to highlight the prejudices and misunderstandings that currently limit the extent and quality of such collaboration. It is reasoned that the complex engineering challenges of the future demand a move towards greater interdisciplinarity. Current successful approaches towards fostering interdisciplinarity within the Carbon Dioxide Utilisation (CDU) research community are then used to illustrate the benefits of employing a more holistic approach to the design and introduction of new industrial technologies. It is our hope that this article will catalyse similar collaborative research efforts within other sectors. Full article

Graphene oxide (GO) has been shown to be reduced by several microorganisms. Recent studies of the growth of Geobacter species in the presence of GO and electricity production by recovery of electrons on the reduced form of GO (rGO) have indicated substantial benefits of GO and GO-respiring bacteria (GORB) in microbial electrochemical systems. In this study, we enriched GORB from a coastal sample to investigate the distribution and phylogenetic variety of GORB in seawater environments. X-ray photoelectron spectroscopy (XPS) and four-terminal probing revealed that the enriched microbial community (designated as CS culture) reduced GO and self-aggregated into a conductive hydrogel complex with rGO (the CS-rGO complex). In the process of GO reduction, certain bacterial populations grew in a manner that was dependent on GO respiration coupled with acetate oxidization. High-throughput sequencing of 16S rRNA as a biomarker revealed the predominance of Desulfomonas species at 92% of the total bacterial population in the CS culture. The CS-rGO complex produced electricity with acetate oxidization, exhibiting less than 1 Ω/cm³ of charge transfer resistance. Thus, these results suggested that Desulfomonas species could grow on rGO and produce electricity via the reduced form of GO. Full article

GUITAR (Graphene from the University of Idaho Thermolyzed Asphalt Reaction) has the classical basal and edge plane morphology of graphites and thin layer graphenes with similar X-ray photoelectron spectroscopy (XPS), Raman and IR characteristics. However previous investigations indicated GUITAR is different electrochemically from graphenes and classical graphites. GUITAR has faster heterogeneous electron transfer across its basal plane and an electrochemical window that exceeds graphitic materials by 1 V. These beneficial properties are examined for application in the negative electrode of the vanadium redox flow battery (VRFB). Graphitic materials in this application suffer from hydrogen gassing and slow electron transfer kinetics for the V^2+/3+ redox couple. Cyclic voltammetry of the V^2+/3+ redox couple (0.05 M V³⁺ in 1 M H₂SO₄) on bare KFD graphite felt gives an estimated standard rate constant (k⁰) of 8.2 × 10⁻⁷ cm/s. The GUITAR-coated KFD graphite felt improves that quantity to 8.6 × 10⁻⁶ cm/s. The total contribution of the cyclic voltammetric currents at −1.0 V vs. Ag/AgCl to hydrogen evolution is 3% on GUITAR-coated KFD graphite felt. On bare KFD graphite felt, this is 22%. These results establish GUITAR as an excellent alternative material for the negative electrode in the vanadium redox flow battery. Full article

The mediatorless electroanalytical sensing of sulfide is explored at a range of commercially available graphitic based electrodes namely, edge and basal plane pyrolytic graphite (EPPGE and BPPGE, respectively), boron-doped diamond (BDDE), glassy carbon (GCE) and screen-printed electrodes (SPE). The electrochemical performance is evaluated in terms of current density/analytical signal and oxidation potential, where the GCE and SPE are found to possess the optimal electrochemical responses. The electroanalytical performance of the GCE is explored towards the electrochemical sensing of sulfide and it is found that it is hampered by sulfide passivation, thus requiring pretreatment in the form of electrode polishing between each measurement. We demonstrate that SPEs provide a simple analytically comparable alternative, which, due to their scales of economy, create disposable, one-shot sensors that do not require any pretreatment of the electrode surface. To the best of our knowledge, this is the first report using mediatorless SPEs (bare/unmodified) towards the sensing of sulfide. In addition, the electroanalytical efficacy of the SPEs is also explored towards the detection of sulfide within model aqueous solutions and real drinking water samples presenting good apparent recoveries, justifying the plausibility of this graphitic mediatorless screen-printed platform. Full article

Of late, graphene has occupied the attention of almost all researchers working globally in the area of materials science. Graphene nanocomposites are the latest additions to the wonder applications of graphene. One of the promising applications of the graphene-oxide nanocomposites is chemical sensing which is useful for monitoring the toxicity, inflammability, and explosive nature of chemicals. Well known binary oxides like ZnO, TiO₂, SnO₂, WO₃, and CuO when combined with graphene in the form of nanocomposites have excellent potential for detecting trace amounts of hazardous gases and chemicals. In this article the preparations, characterizations, and the chemical sensor applications of graphene-oxide nanocomposites are presented in detail. Full article

This study highlights the economic and environmental challenges of recycling in Ontario, specifically examining the effect of attempting to increase the emissions target for the province’s Waste Electronics (WEEE) program. The findings from the cost model analysis found that Ontario’s Electronic Stewardship program reduces overall carbon emissions by approximately 205 thousand tonnes every year. This study also found that targeting specific materials for recovery could result in a scenario where the province could improve emissions offsets while reducing material management costs. Under our modeled scenario, as the tonnes of greenhouse gases (GHGs) avoided increases, the system cost per tonne of GHG avoided initially declines. However, after avoiding 215 thousand tonnes of GHGs (the optimal point), the system cost/tonne GHG avoided increases. To achieve an emissions target in excess of 215 thousand tonnes, the province will have to have to start recycling higher cost difficult to recycle materials (display monitors, computer peripherals, etc.). Full article

Mixed matrix membranes (MMM) based on chitosan (CS) and poly (vinyl) alcohol (PVA) with a 50:50 w/w ratio doped with graphene oxide (GO) are prepared by solution casting and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake, alcohol permeability, ion exchange capacity (IEC) and OH⁻ conductivity measurements. The SEM analysis revealed a dense MMM where the GO nanosheets were well dispersed over the entire polymer matrix. The incorporation of GO increased considerably the thermal stability of the CS:PVA membrane. The GO-based MMM exhibited a low conductivity of 0.19 mS·cm⁻¹ in part because the GO sheets did not change the crystallinity of the CS:PVA matrix. The reinforced structure created by the hydrogen bonds between the GO filler and the CS:PVA matrix resulted to be a good physical barrier for alcohol permeability, achieving a coefficient of diffusion of 3.38 × 10⁻⁷ and 2.43 × 10⁻⁷ cm²·s⁻¹ after 60 and 120 min, respectively, thus avoiding additional alcohol crossover. Finally, the electrochemical performance of the GO-based MMM in the electrooxidation of propargyl alcohol was investigated in a Polymer Electrolyte Membrane Electrochemical Reactor (PEMER) under alkaline conditions, through the polarization curve and the electrolysis reactions, showing a performance comparable to anion-exchange commercial membranes. Full article

Amorphous BCN ceramics were synthesized via a thermal conversion procedure of piperazine–borane and pyridine–borane. The synthesized BC₂N and BC₄N ceramics contained, in their final amorphous structure, 45 and 65 wt % of carbon, respectively. Elemental analysis revealed 45 and 65 wt % of carbon for BC₂N and BC₄N, respectively. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed the amorphous nature of studied compounds. Lateral cluster size of carbon crystallites of 7.43 and 10.3 nm for BC₂N and BC₄N, respectively, was calculated from Raman spectroscopy data. This signified a higher order of the carbon phase present in BC₄N. The electrochemical investigation of the low carbon BC₂N composition as anodes for Li-ion batteries revealed initial capacities of 667 and 235 mAh·g⁻¹ for lithium insertion/extraction, respectively. The material with higher carbon content, BC₄N, disclosed better reversible lithium storage properties. Initial capacities of 1030 and 737 mAh·g⁻¹ for lithium insertion and extraction were recovered for carbon-rich BC₄N composition. Extended cycling with high currents up to 2 C/2 D revealed the cycling stability of BC₄N electrodes. Cycling for more than 75 cycles at constant current rates showed a stable electrochemical behavior of BC₄N anodes with capacities as high as 500 mAh·g⁻¹. Full article