(Left) Silicon wires with match heads and (right) light absorption profile of a single match-head wire at 587 nm absorption. Credit: Image courtesy of the Center for Integrated Nanotechnologies
Crystal growth on a nano/microscale level produces “match-head”-like, 3D structures that enhance light absorption and photovoltaic efficiency. This is the first large structure grown on a nanowire tip and it creates a completely new architecture for harnessing energy. Match-head semiconductor nanowires focus incident light for greater overall efficiency. The match heads are naturally formed during the wire-growth process, which can be applied to various materials and structures for photonic and optoelectronic devices.
Enhanced light absorption and efficient, photogenerated carrier collection are...
Researchers have built a locust-inspired robot that is just 5 inches long, 23 grams, but can jump 11 feet high and cover a horizontal distance of 4.5 ft. This jump height is more than twice the height of similar-sized jumping robots, and is 25X higher than its own length. The robot could have applications in search-and-rescue missions, reconnaissance, and environmental monitoring in rough terrain.
The team of researchers, Valentin Zaitsev, et al is from Tel Aviv University and Ort Braude College, Israel, which inspired the name of the robot: TAUB (Tel Aviv University and Braude College). “We demonstrate a design that is closer to nature,” Zaitsev...
Visualized model of a superlubricity (low-friction) system: gold = nanodiamond particles; red = graphene nanoscroll; green = underlying graphene on silica; black = diamond-like carbon surface. Credit: Image courtesy of Argonne National Laboratory
Friction hampers the movement of all mechanical parts, including engines for transportation. At the Center for Nanoscale Materials, scientists built a system with virtually no friction. The system wraps graphene flakes around nanodiamonds that then roll between a diamond-like carbon-surface and graphene on silica. Such hard ball bearings wrapped in slippery Teflon(R) tissue paper rolling between 2 surfaces reduces the friction to almost zero.
Creating a low-friction situation has the potential for substantial cost savings because friction accounts...
Schematic of a “solar flow battery” with the three-electrode configuration: lithium anode electrode, counter electrode (CE), and photo-electrode (PE). Current passes through a liquid in the battery called an electrolyte. The portion of the electrolyte near the cathode electrode is called a “catholyte.” The CE and PE electrodes are in contact with the “catholyte.” Credit: Image courtesy of Yiying Wu, The Ohio State University
More efficient, eco-friendly electricity generation with a “solar flow battery” combines a redox flow battery and a dye-sensitized solar cell, using compatible, water-based (aqueous) solvents. Solar energy is harvested and stored as chemical energy during the charging process. When it is time to recharge the battery, the amount of energy needed to is lower than conventional lithium-iodine batteries because dye molecules, exposed to the sun, donate electrons to the recharging process.
Energy generation from a solar flow battery is more cost-effective, eco-friendly, and can achieve energy savings up to 20% compared to conventional lithium-iodine batteries. Solar flow batteries make renewable solar energy more practical for keeping the lights on and appliances running with stand-alone electricity generation and storage.
Last year, researchers at The Ohio State University demonstrated photo-assisted charging of a lithium-oxygen (Li-O2) battery; however, they used organic (carbon-based) solvents that limited its compatibility with aqueous redox flow batteries. Now, these researchers have built a solar flow battery that uses an eco-friendly, compatible solvent and requires a lower applied voltage to recharge the battery. In solar flow batteries, the proposed charging process links harvesting solar energy and storing it as chemical energy via the electrolyte.
The aqueous electrolyte is in contact with the counter electrode of the battery and the dye-sensitized photo-electrode of the solar cell. To recharge the battery, it is exposed to sunlight. The sunlight causes the dye molecules in the electrolyte to donate electrons to the photo-electrode, reducing the amount of energy needed to recharge the battery. The applied voltage to recharge the solar flow battery is reduced to 2.9 Volts compared to > 3.6 Volts for conventional lithium-iodine batteries, resulting in an energy savings of up to 20%.
The aqueous solar flow battery performs better and is more cost-effective and eco-friendly than those based on organic solvents. The aqueous solar flow battery could solve the intermittency shortcomings of renewable energy and keep the lights on and appliances running. http://science.energy.gov/bes/highlights/2015/bes-2015-10-f/
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