Category Chemistry/Nanotechnology

Structure of tandem devices and photoelectrochemical characterization.

Scientists at the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) recaptured the record for highest efficiency in solar hydrogen production via a photoelectrochemical (PEC) water-splitting process. The new solar-to-hydrogen (STH) efficiency record is 16.2%, topping a reported 14% efficiency in 2015 by an international team from Helmholtz-Zentrum Berlin, TU Ilmenau, Fraunhofer ISE and the California Institute of Technology. The record-setting PEC cell represents a significant change from the concept device Turner developed at NREL in the 1990s.

Both the old and new PEC processes employ stacks of light-absorbing tandem semiconductors that are immersed in an acid/water solution (electrolyte) w...

Illustrations of the design principles of using methyl viologen to form a stable coating to allow the stable cycling of lithium metal. Credit: UC Riverside

High performing lithium-ion batteries are a key component of laptops, smart phones, and electric vehicles. Currently, the anodes side of lithium ion batteries, are generally made with graphite or other carbon-based materials. But, the performance of carbon based materials is limited because of the weight and energy density, which is the amount of energy that can be stored in a given space. As a result, a lot of research is focused on lithium-metal anodes.

The success of lithium metal anodes will enable many battery technologies, including lithium metal and lithium air, which can potentially increase the capacity of today’s best lithium-...

The Structure and Rechargeability of a Room-Temperature Li-N2 Battery
(A) Structure of a Li-N2 battery with a Li-foil anode, ether-based electrolyte, and CC cathode.
(B) N2 fixation (blue) and N2 evolution (red) curves of a Li-N2 battery with a CC cathode at a current density of 0.05 mA cm−2.
(C) CV curves of a Li-N2 battery at a scan rate of 0.05 mV s−1 in N2-saturated (black) and Ar-saturated (red) atmospheres.
(D) Cyclic performance of a Li-N2 battery at a current density of 0.05 mA cm−2.

As the most abundant gas in Earth’s atmosphere, nitrogen has been an attractive option as a source of renewable energy...

This is the water harvester built at MIT with MOFs from UC Berkeley. Using only sunlight, the harvester can pull liters of water from low-humidity air over a 12-hour period. Credit: MIT photo from laboratory of Evelyn Wang

Metal-organic framework sucks up water from air with humidity as low as 20%. Imagine a future in which every home has a solar appliance that pulls all the water the household needs out of the air, even in desert climates. That future may be around the corner, with the demonstration this week of a water harvester that uses only ambient sunlight to pull liters of water out of the air each day with very low humidity. The solar-powered harvester was constructed at MIT using a special material – a metal-organic framework, or MOF – produced at UC, Berkeley.

Omar Yaghi, scienti...