We analyzed the metabolic activity of Shewanella oneidensis MR-1 respiring on an indium tin-doped oxide electrode with nanoscale secondary ion mass spectrometry (NanoSIMS) for quantification of the anabolism of 15N-labeled NH4Cl. Although acceleration of extracellular electron transfer (EET) did not enhance the average metabolic activity, the distribution of 15N intake among individual cells was drastically bipolarized upon EET rate enhancement, suggesting not only positive but also negative effects on cellular activity. The present data highlight the importance of controlling the downregulation of metabolic activity caused by the rate acceleration of EET to improve the efficiency of microbial electrode catalysis.
After preparing LiFePO4 (LFP) and activated carbon (AC) layers on each face of an aluminum current collector, through-holes with the pore diameter of 22 µm and opening rate of 0.5% were formed on the electrode. A half cell was fabricated with the electrode and two lithium (Li) metal electrodes. The half-cell exhibited much improvement of rate performance. Because the LFP/AC electrode having no through holes and LFP electrode did not exhibit the improvement, it was considered that energy and Li+ transfer occurred between LFP and AC layers, and Li+ passed through the holes from AC to LFP.
In this work porous MgO fibers were prepared by a hydrothermal method and modified by the reaction with different amounts of hydrofluoric acid solution. Their composition, morphology and porosity were characterized. Separators for thermal batteries were prepared by mixing of definite amounts of dry electrolyte powder (LiCl:KCl = 45:55 wt%) with MgO powder, pristine porous MgO fiber or hydrofluoric acid modified porous MgO fiber. The electrolyte leakage of the separator using the modified porous fibers as the immobilizing agent is lower than that of the separator using MgO powder or pristine fiber as the immobilizing agent. Moreover, the model cells using the modified porous MgO fiber as the immobilizing agent show longer discharge time and larger specific capacity compared with the model cells using MgO powder or pristine fiber as the immobilizing agent. It can be concluded that porous magnesia fibers modified by hydrofluoric acid are a promising immobilizing agent for electrolyte in thermal batteries.
The inhibition ability of 1-hydroxy benzotriazole (BTAOH) for mild steel in HCL solution (1 mol/L) had been investigated in this manuscript. The inhibition efficiency of BTAOH showed a maximum value around 48% at 303 K, with the concentration 1.5 × 10−3 mol/L. The physical adsrobed BTAOH molecules are more stable attached onto the mild steel surface than the corrosion products. The similar free energy of adsorption (Δ Gads0) but much lower IE were ascribed to the thicker but less compact film constructed by the zig-zag H-bond connected BTAOH polymers. According to the effects of concentration and temperature on the adsorption behavior of the BTAOH, we had calculated the Δ Gads0, Ea, Δ Hads0, Δ Sads0 as −26.76, 75.50, −36.14 kJ/mol and −0.0310 kJ/mol/K respectively.
Poly[Ni(salen)] films were electropolymerized on multiwalled carbon nanotubes (MWCNTs) in tetrabutylammonium perchlorate/acetonitrile by cyclic voltammetry method. And the employed scan rates were 5, 10, 20 and 40 mV s−1. The effect of sweep rate on the growth of poly[Ni(salen)] was investigated by the apparent surface coverage (Γ) analysis, in which Γ increased almost proportionally with the scan number for all applied scan rates. Fourier transform infrared spectroscopy and field-emission scanning electron microscope images verified the successful deposition of poly[Ni(salen)]. It demonstrated that Ni(salen) were oxidized at the interface between the electrolyte and substrate surface and then the oxidized monomers were cross linked on the substrate. The galvanostatic charge/discharge plots displayed the specific capacitance of 62.8, 78.8, 161.4 and 135.1 F g−1 for 5, 10, 20 and 40 mV s−1 (0.05 mA g−1), respectively. Poly[Ni(salen)] grown at 20 mV s−1 possessed the maximum capacity and decreased as the scan rate increased because the monomer diffusion impeded the growth of poly[Ni(salen)]. The charge diffusion coefficient (D) was found highest with the sweep rate of 20 mV s−1. The excellent electrochemical performance of poly[Ni(salen)] electropolymerized at 20 mV s−1 is ascribed to the better conductivity and superior diffusion ability according to the kinetics.
Non-precious metal catalyst materials such as carbon-based catalysts and transition metal chelate compounds have been investigated for reducing the cost of polymer electrolyte fuel cells (PEFCs). Our research on the synthesis of such catalysts has involved vacuum heat treatment for the preparation of iron phthalocyanine (FePc). When a composite of FePc and Ketjenblack carbon was synthesized by vacuum heat treatment at ≥350°C for 10 h, FePc was deposited as a thin film on the Ketjenblack. Furthermore, synthesis with the vacuum heat treatment at 400°C for 10 h (FePc/C-400) transformed the FePc structure from the α phase to the β phase. The oxygen reduction reaction (ORR) activity of FePc/C-400 was higher than those of other FePc/C catalysts treated at different temperatures. The coordination of Fe and N in β-FePc was found to be related to the high ORR activity.
Conversion-type cathode materials such as perovskite-type MF3 (M = Fe and Ti) show promise for use in large-scale lithium-ion batteries by virtue of their low cost and large specific capacities. However, the FeF3 cathode shows a large overpotential during discharge-charge cycles, such that the rechargeable capacity is almost gone after a few cycles. To overcome this drawback, we elucidated the detailed mechanism of the deterioration of the rechargeable capacity for the FeF3 cathode. In the initial cycle, the cathode returned to the initial FeF3 structure from LiF and Fe. However, the diffraction peak of LiF and Fe after the 20th cycle was sharper than that after the initial discharge state; that is, the growth of the LiF and Fe crystal contributed to the lower cyclability of FeF3. On the other hand, the TiF3 cathode showed an initial discharge/charge capacity of 730/620 mAh g−1 between 0.5 and 4.0 V, and the discharge-charge overpotential of TiF3 was still smaller than that of FeF3. In addition, the cyclability of the TiF3 cathode were better than that of the FeF3 cathode, not only in insertion reaction region, but also in conversion reaction region.