Li4Ti5O12 Nanocrystals Synthesized by Carbon Templating from Solution Precursors Yield High Performance Thin Film Li‐Ion Battery Electrodes

Nanocrystals of Li₄Ti₅O₁₂ (LTO) have been prepared by processing an ethanol‐toluene solution of LiOEt and Ti(OiPr)₄ using a carbon black template. The mechanism of crystal growth has been tracked by SEM and TEM microscopies. The resulting nanocrystals grown using the carbon template (C‐LTO) show less aggregation than materials prepared from solution without the template (S‐LTO), which is reflected in higher surface area (27 m²/g) and concomitantly smaller particle size (58 nm) for C‐LTO compared to 20 m²/g and 201 nm for S‐LTO. Electrochemically, thin‐film electrodes composed of C‐LTO demonstrate reversible cycling, storing ～160 mAh/g at both 1 C (175 mA/g) and 10 C current. Important is that resistance to charge transfer between the C‐LTO nanocrystals and added conducting carbon is 3 times smaller than that for S‐LTO. Accordingly, C‐LTO shows excellent rate capability, maintaining an energy‐storage capacity >150 mAh/g even at 100 C current. These characteristics solidify C‐LTO a suitable replacement for carbon as a Li‐ion battery anode.     

Three-dimensional cerebrospinal fluid flow within the human ventricular system

Cerebrospinal fluid (CSF) is a Newtonian fluid and can, therefore, be modelled using computational fluid dynamics (CFD). Previous modelling of the CSF has been limited to simplified geometric models. This work describes a geometrically accurate three dimensional (3D) computational model of the human ventricular system (HVS) constructed from magnetic resonance images (MRI) of the human brain. It is an accurate and full representation of the HVS and includes appropriately positioned CSF production and drainage locations. It was used to investigate the pulsatile motion of CSF within the human brain. During this investigation CSF flow rate was set at a constant 500 ml/day, to mimic real life secretion of CSF into the system, and a pulsing velocity profile was added to the inlets to incorporate the effect of cardiac pulsations on the choroid plexus and their subsequent influence on CSF motion in the HVS. Boundary conditions for the CSF exits from the ventricles (foramina of Magendie and Lushka) were found using a “nesting” approach, in which a simplified model of the entire central nervous system (CNS) was used to examine the effects of the CSF surrounding the ventricular system (VS). This model provided time varying pressure data for the exits from the VS nested within it. The fastest flow was found in the cerebral aqueduct, where a maximum velocity of 11.38 mm/s was observed over five cycles. The maximum Reynolds number recorded during the simulation was 15 with an average Reynolds number of the order of 0.39, indicating that CSF motion is creeping flow in most of the computational domain and consequently will follow the geometry of the model. CSF pressure also varies with geometry with a maximum pressure drop of 1.14 Pa occurring through the cerebral aqueduct. CSF flow velocity is substantially slower in the areas that are furthest away from the inlets; in some areas flow is nearly stagnant.     

TiO2 Nanocrystals Synthesized by Laser Pyrolysis for the Up‐Scaling of Efficient Solid‐State Dye‐Sensitized Solar Cells

A crucial issue regarding emerging nanotechnologies remains the up‐scaling of new functional nanostructured materials towards their implementation in high performance applications on a large scale. In this context, we demonstrate high efficiency solid‐state dye‐sensitized solar cells prepared from new porous TiO₂ photoanodes based on laser pyrolysis nanocrystals. This strategy exploits a reduced number of processing steps as well as non‐toxic chemical compounds to demonstrate highly porous TiO₂ films. The possibility to easily tune the TiO₂ nanocrystal physical properties allows us to demonstrate all solid‐state dye‐sensitized devices based on a commercial benchmark materials (organic indoline dye and molecular hole transporter) presenting state‐of‐the‐art performance comparable with reference devices based on a commercial TiO₂ paste. In particular, a drastic improvement in pore infiltration, which is found to balance a relatively lower surface area compared to the reference electrode, is evidenced using laser‐synthesized nanocrystals resulting in an improved short‐circuit current density under full sunlight. Transient photovoltage decay measurements suggest that charge recombination kinetics still limit device performance. However, the proposed strategy emphasizes the potentialities of the laser pyrolysis technique for up‐scaling nanoporous TiO₂ electrodes for various applications, especially for solar energy conversion.     

Involvement of reactive oxygen species in the electrochemical inhibition of barnacle (Amphibalanus amphitrite) settlement

The role of reactive oxygen species (ROS) in electrochemical biofouling inhibition was investigated using a series of abiotic tests and settlement experiments with larvae of the barnacle Amphibalanus amphitrite, a cosmopolitan fouler. Larval settlement, a measure of biofouling potential, was reduced from 43% ± 14% to 5% ± 6% upon the application of pulsed electric signals. The application of ROS scavengers such as glutathione and catalase counteracted the inhibitory effects of the electric signals, allowing settlement, and thus indicating that ROS are antifouling agents. Based on the experimental evidence, the proposed mechanism for ROS-based fouling prevention with interdigitated electrodes involved the electrochemical generation of hydrogen peroxide by oxygen reduction, and its likely reduction to hydroxyl radicals. Either hydroxyl radicals or products of hydroxyl radical reactions appeared to be the main deterrents of larval settlement.     

Vitamin B(12) incorporated with multiwalled carbon nanotube composite film for the determination of hydrazine

Electrochemically active composite film containing multiwalled carbon nanotubes (MWCNTs) and vitamin B₁₂ was synthesized on glassy carbon, gold, and indium tin oxide electrodes by the potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT–B₁₂) modified electrode mediates vitamin B₁₂’s redox reaction, whereas vitamin B₁₂’s redox reaction does not occur at bare electrode. The electrochemical impedance spectroscopy studies reveal that MWCNTs present in MWCNT–B₁₂ film enhance electron shuttling between the reactant and electrode surface. The surface morphology of bare electrode, MWCNT film. and MWCNT–B₁₂ composite film was studied using atomic force microscopy, which reveals vitamin B₁₂ incorporated with MWCNTs. The MWCNT–B₁₂ composite film exhibits promising enhanced electrocatalysis toward hydrazine. The electrocatalysis response of hydrazine at MWCNT film and MWCNT–B₁₂ composite film was measured using cyclic voltammetry and amperometric current–time (i–t) curve techniques. The linear concentration range of hydrazine obtained at MWCNT–B₁₂ composite film using the i–t curve technique is 2.0 μM–1.95 mM. Similarly, the sensitivity of MWCNT–B₁₂ composite film for hydrazine determination using the i–t curve technique is 1.32 mA mM⁻¹ cm⁻², and the hydrazine’s limit of detection at MWCNT–B₁₂ composite film is 0.7 μM.     

High Performance Flexible Transparent Electrode via One‐Step Multifunctional Treatment for Ag Nanonetwork Composites Semi‐Embedded in Low‐Temperature‐Processed Substrate for Highly Performed Organic Photovoltaics

For ideal flexible transparent electrodes, the features of good electrical/optical properties, low surface roughness, efficient charge transportation, robust electrical stability under simultaneously continuous operation bias, and mechanical bending are critical. Herein, a flexible transparent electrode fulfilling all these features is demonstrated by silver (Ag) nanonetwork composites semi‐embedded in low‐temperature‐processed colorless polyimide (cPI), which shows a figure of merit over 1000 (5.4 Ω sq^?1 sheet resistance and >94% diffused transmission at 550 nm wavelength), extremely smooth topography (<1 nm root‐mean‐square roughness and <3 nm peak‐to‐valley roughness), remarkable bending stability under continuous operation bias, and increased work function favoring the band alignment with typical charge transport layers for efficient devices. These characteristics are attributed to one‐step multifunctional chemical treatment on the composite of Ag nanowires and an example polymer of poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The strategic one‐step process simultaneously offers selective welding at nanowires cross junctions to form an Ag nanonetwork, and removing polyvinylpyrrolidone surfactant from Ag nanowires and PSS from PEDOT:PSS. The flexible electrode also favors the residue‐free cPI transfer for applications. Flexible organic solar cells (OSCs) made from the electrode achieve an averaged power conversion efficiency of 14.46% (best, 15.12%), which is the best flexible OSCs reported so far.     

Alkaline Water Electrolysis at 25 A cm−2 with a Microfibrous Flow‐through Electrode

The generation of renewable electricity is variable, leading to periodic oversupply. Excess power can be converted to H₂ via water electrolysis, but the conversion cost is currently too high. One way to decrease the cost of electrolysis is to increase the maximum productivity of electrolyzers. This study investigates how nano‐ and microstructured porous electrodes can improve the productivity of H₂ generation in a zero‐gap, flow‐through alkaline water electrolyzer. Three nickel electrodes—foam, microfiber felt, and nanowire felt—are studied to examine the tradeoff between surface area and pore structure on the performance of alkaline electrolyzers. Although the nanowire felt with the highest surface area initially provides the highest performance, this performance quickly decreases as gas bubbles are trapped within the electrode. The open structure of the foam facilitates bubble removal, but its small surface area limits its maximum performance. The microfiber felt exhibits the best performance because it balances high surface area with the ability to remove bubbles. The microfiber felt maintains a maximum current density of 25 000 mA cm^?2 over 100 h without degradation, which corresponds to a hydrogen production rate 12.5‐ and 50‐times greater than conventional proton‐exchange membrane and alkaline electrolyzers, respectively.