Transition metal oxyhydroxides have been used as promising electrocatalysts for water splitting however, their catalytic activity is restricted due to low surface area and poor conductivity. Herein, we report novel composite FeOOH@ZIF-12/graphene composite as electrocatalyst for water oxidation, whereby ZIF-12 provide extra surface for the FeOOH dispersion whilst graphene act as excellent electron mediator. The composite shows a low overpotential value of 291 mV to attain a current density of 10 mA cm?2 and a low Tafel slope value of 78 mV dec?1. The catalyst offers a maximum current density of 101 mA cm?2, while it gives a turnover frequency (TOF) value of 0.031 s?1 at an overpotential of 291 mV only. The excellent activity and remarkable stability of composite is attributed to highly conductive and porous support. 相似文献
Piezoelectric nanogenerators (PENG) with flexible and simple design have pronounced significance in fabricating sustainable devices for self-powering electronics. This study demonstrates the fabrication of electrospun nanocomposite fibers from polyvinylidene fluoride (PVDF) filled zinc oxide (ZnO)/iron oxide (FeO) nanomaterials. The nanocomposite fiber based flexible PENG shows piezoelectric output voltage of 5.9 V when 3 wt% of ZnO/FeO hybrid nanomaterial is introduced, which is 29.5 times higher than the neat PVDF. No apparent decline in output voltage is observed for almost 2000 s attributed to the outstanding durability. This higher piezoelectric output performance is correlated with the β-phase transformation studies from the Fourier transformation infrared spectroscopy and the crystallinity studies from the differential scanning calorimetry. Both these studies show respective enhancement of 3.79 and 2.16% in the β-phase crystallinity values of PVDF-ZnO/FeO 3 wt% composite. Higher dielectric constant value obtained for the same composite (three times higher than the neat PVDF) confirms the increased energy storage efficiency as well. Thus the proposed soft and flexible PENG is a promising mechanical energy harvester, and its good dielectric properties reveals the ability to use this material as good power sources for wearable and flexible electronic devices.
Microalgae biomass has great potential for being used as feedstock for the sustainable production of biodiesel, as it is able to produce 7–31 times more oil than the top terrestrial crop. It is a green alternative to the currently utilized energy sources as it can reduce CO, CO2 and hydrocarbon emissions. However, downstream processing costs for the dilute biomass are a major challenge. Foam flotation has been recently investigated for the recovery of microalgae cells from dilute liquid suspensions. A number of variables on the effectiveness of foam flotation for microalgae have been investigated, which include surfactant type and concentration, cell concentration, pH, hydrophobicity, time, growth stage, flow rate, ionic strength, alkalinity, temperature, bubble size, and column size. It appears to be a promising method for the recovery of algae for biofuel production, as a result of the high removal recoveries, good enrichment ratios, ability to process large volumes of biomass, and its ease of operation. However, literature on this subject is scarce, and there are research gaps that should be investigated including characterization of microalgae cells and impact on foam separation and the effect of surfactant as a treatment prior to lipid extraction. 相似文献
This paper proposes a variable neighborhood descent heuristic for solving a capacitated arc routing problem with time-dependent service costs. The problem is motivated by winter gritting applications where the timing of each intervention is crucial. The variable neighborhood descent is based on neighborhood structures that manipulate arcs or sequences of arcs. Computational results are reported on problems derived from classical capacitated arc routing problem instances. A comparison is also provided with an alternative approach where the arc routing problem is solved after being transformed into an equivalent node routing problem. 相似文献