3D polarization correlometry of object fields of networks of biological crystals

The results of the study of the relationships between 3D divisions of the optical anisotropy parameters of polycrystalline networks of films of biological fluids of various biochemical composition and layer-by-layer phase cross sections of volume distributions of the magnitude and phase parameters of the "two-point" Stokes vector of a microscopic image are presented. In the framework of the statistical approach using scale-selective wavelet analysis, the values and ranges of statistical 1st-4th order changes are defined, which characterize: • distribution of the values of the modulus and phase of the parameters of the Stokes vector in various phase sections of the object field; • a set of values of the amplitudes of the wavelet coefficients for various scales of the geometric dimensions of the module maps and the phase of the degree of correlation of the parameters of the Stokes vector (DCS)

Technical and economic feasibility of centralized facilities for solar hydrogen production via photocatalysis and photoelectrochemistry

Photoelectrochemical water splitting is a promising route for the renewable production of hydrogen fuel. This work presents the results of a technical and economic feasibility analysis conducted for four hypothetical, centralized, large-scale hydrogen production plants based on this technology. The four reactor types considered were a single bed particle suspension system, a dual bed particle suspension system, a fixed panel array, and a tracking concentrator array. The current performance of semiconductor absorbers and electrocatalysts were considered to compute reasonable solar-to-hydrogen conversion efficiencies for each of the four systems. The U.S. Department of Energy H2A model was employed to calculate the levelized cost of hydrogen output at the plant gate at 300 psi for a 10 tonne per day production scale. All capital expenditures and operating costs for the reactors and auxiliaries (compressors, control systems, etc.) were considered. The final cost varied from $1.60–$10.40 per kg H2 with the particle bed systems having lower costs than the panel-based systems. However, safety concerns due to the cogeneration of O_2 and H_2 in a single bed system and long molecular transport lengths in the dual bed system lead to greater uncertainty in their operation. A sensitivity analysis revealed that improvement in the solar-to-hydrogen efficiency of the panel-based systems could substantially drive down their costs. A key finding is that the production costs are consistent with the Department of Energy's targeted threshold cost of $2.00–$4.00 per kg H_2 for dispensed hydrogen, demonstrating that photoelectrochemical water splitting could be a viable route for hydrogen production in the future if material performance targets can be met

Review—Practical Challenges Hindering the Development of Solid State Li Ion Batteries

Solid state electrolyte systems boasting Li+conductivity of >10 mS cm−1at room temperature have opened the potential for developing a solid state battery with power and energy densities that are competitive with conventional liquid electrolyte systems. The primary focus of this review is twofold. First, differences in Li penetration resistance in solid state systems are discussed, and kinetic limitations of the solid state interface are highlighted. Second, technological challenges associated with processing such systems in relevant form factors are elucidated, and architectures needed for cell level devices in the context of product development are reviewed. Specific research vectors that provide high value to advancing solid state batteries are outlined and discussed. Keywords: dendrite; Li ion battery; Li ion conductor; Li metal anode; solid electrolyte; solid state batteryUnited States. Department of Energy (Award DE-EE0007810

Meso-Structured Platinum Thin Films: Active and Stable Electrocatalysts for the Oxygen Reduction Reaction

Improving both the activity and the stability of the cathode catalyst in platinum-based polymer electrolyte fuel cells is a key technical challenge. Here, we synthesize a high surface area meso-structured Pt thin film that exhibits higher specific activity for the oxygen reduction reaction (ORR) than commercial carbon-supported Pt nanoparticles (Pt/C). An accelerated stability test demonstrates that the meso-structured Pt thin film also displays significantly enhanced stability as compared to the commercial Pt/C catalyst. Our study reveals the origin of the high turnover frequency (TOF), and excellent durability is attributed to the meso-structure, which yields a morphology with fewer undercoordinated Pt sites than Pt/C nanoparticles, a key difference with substantial impact to the surface chemistry. The improved catalyst activity and stability could enable the development of a high-performance gas diffusion electrode that is resistant to corrosion even under the harsh conditions of start-up, shut-down, and/or hydrogen starvation

High Surface Area Transparent Conducting Oxide Electrodes with a Customizable Device Architecture

Herein, we report the development of optically transparent high surface area electrodes (HSEs) made of indium tin oxide (ITO) using a facile, template-free, scalable wet chemical synthetic approach. The transparent HSEs are electronically conductive and physically robust, with tunable electrochemically accessible roughness factors from 1 through ∼100. These transparent HSEs can serve as a broadly functionalizable scaffold ideally suited to bridge the gap between the need to minimize ionic and electronic transport lengths within a device and the need to achieve high loadings of active material per surface area (e.g. for high capacity as needed for batteries or high optical density as required for electrochromics or photovoltaics). This gap currently stands as a major hurdle for the utilization of many nanomaterials in electronic and optoelectronic devices. The synthetic approach described here for ITO is transferable to other transparent conducting oxide (TCO) materials. This is the first report of a large-pore, tunable, high surface area TCO electrode with excellent optical and conductive properties

Amorphous Molybdenum Sulfide Catalysts for Electrochemical Hydrogen Production: Insights into the Origin of their Catalytic Activity

We present a scalable wet chemical synthesis for a catalytically active nanostructured amorphous molybdenum sulfide material. The catalyst film is one of the most active nonprecious metal materials for electrochemical hydrogen evolution, drawing 10 mA/cm² at ∼200 mV overpotential. To identify the active phase of the material, we perform X-ray photoelectron spectroscopy after testing under a variety of conditions. As deposited, the catalyst resembles amorphous MoS₃, but domains resembling MoS₂ in composition and chemical state are created under reaction conditions and may contribute to this material’s high electrochemical activity. The activity scales with electrochemically active surface area, suggesting that the rough, nanostructured catalyst morphology also contributes substantially to the film’s high activity. Electrochemical stability tests indicate that the catalyst remains highly active throughout prolonged operation. The overpotential required to attain a current density of 10 mA/cm² increases by only 57 mV after 10 000 reductive potential cycles. Our enhanced understanding of this highly active amorphous molybdenum sulfide hydrogen evolution catalyst may facilitate the development of economical electrochemical hydrogen production systems