Subscribe to our free daily newsletters
  Solar Energy News  

Subscribe to our free daily newsletters

Ionic 'solar cell' could provide on-demand water desalination
by Staff Writers
Washington DC (SPX) Nov 17, 2017

This is an artist's rendition of bipolar-membrane design for ionic electricity generation.

Modern solar cells, which use energy from light to generate electrons and holes that are then transported out of semiconducting materials and into external circuits for human use, have existed in one form or another for over 60 years.

Little attention has been paid, however, to the promise of using light to drive another electricity-generating process - the transport of oppositely charged protons and hydroxides obtained by dissociating water molecules. Researchers in America report such a design, which has promising application in producing electricity to turn brackish water drinkable, on November 15 in the journal Joule.

The researchers, led by senior author Shane Ardo, an Assistant Professor of Chemistry, Chemical Engineering, and Materials Science at the University of California, Irvine, write that they have crafted an "ionic analog to the electronic pn-junction solar cell," harnessing light to exploit the semiconductor-like behavior of water and generate ionic electricity. They hope to use such a mechanism to manufacture a device that would directly desalinate saltwater upon exposure to sunlight.

"There had been other experiments dating back to the 1980s that photoexcited materials so as to pass an ionic current through them, and theoretical studies said that those currents should be able to reach the same levels as their electronic analogs, but none of them worked all that well," says first author William White, a graduate student in Ardo's research group.

In this case, the researchers attained more success by allowing water to permeate through two ion-exchange membranes, one that mostly transported positively charged ions (cations) like protons and one that mostly transported negatively charged ions (anions) like hydroxides, functioning as a pair of chemical gates to attain charge separation.

Shining a laser on the system prompted light-sensitive organic dye molecules bound to the membrane to liberate protons, which then transported to the more acidic side of the membrane and produced a measurable ionic current and voltages of over 100 mV in some instances (60 mV on average).

Despite crossing the 100 mV photovoltage threshold at times, the level of electric current that the double-membrane system can achieve remains its chief limitation. The photovoltage would need to be magnified by more than another factor of two to reach the ~200 mV mark necessary to desalinate seawater, a target that the researchers are optimistic about hitting.

"It all comes down to the fundamental physics of how long the charge-carriers persist before recombining to form water," Ardo says. "Knowing the properties of water, we are able to more intelligently design one of these bipolar-membrane interfaces so that we can maximize the voltage and the current."

In the long run, desalination is just one possible application of the synthetic light-driven proton pump developed by the researchers. It could also have potential for interfacing with electronic devices, or even for powering signaling in brain-machine interfaces and other "cyborg cells" that combine living tissue and artificial circuity, a role that cannot be filled by traditional solar cells, which are unstable in biological systems.

"We have had a lot of ideas about what this technology could be used for; it's just a question of learning enough to cross between fields and make the device work for those intended applications," says Ardo. "I think this is just another example of what you can do when you have scientists who are trained across many disciplines and think outside the box."

Research Report: Joule, White et al.: "Conversion of visible light into ionic power using photoacid-dye-sensitized bipolar ion-exchange membranes"

Butterfly wing inspires photovoltaics that could triple light absorption
Karlsruher, Germany (SPX) Nov 15, 2017
Sunlight reflected by solar cells is lost as unused energy. The wings of the butterfly Pachliopta aristolochiae are drilled by nanostructures (nanoholes) that help absorbing light over a wide spectrum far better than smooth surfaces. Researchers of Karlsruhe Institute of Technology (KIT) have now succeeded in transferring these nanostructures to solar cells and, thus, enhancing their light absor ... read more

Related Links
Cell Press
All About Solar Energy at

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

To find new biofuel enzymes, it can take a microbial village

Sandia speeds transformation of biofuel waste into wealth

Study identifies additional hurdle to widespread planting of bioenergy crops

Penn researchers mimic giant clams to enhance the production of biofuel

Computer system finds 'recipes' for producing materials

Study shows need for adaptive powered knee prosthesis to assist amputees

Researchers unveil tool to debug 'black box' deep learning algorithms

Physics boosts artificial intelligence methods

End tax credits for wind energy, Tennessee Republican says

New York sets high bar for wind energy

Construction to begin on $160 million Industry Leading Hybrid Renewable Energy Project

A kite that might fly

Lyft takes Uber challenge north to Canada

Vehicle emissions per driver on the rise, study finds

EV corridor will stretch from Norway to Italy

Auto workers at Chinese-owned US plant reject bid to unionize

Study helps make microgrids a more reliable power source

A novel layered superconductor based on tin and arsenic

'Perfectly frustrated' metal provides possible path to superconductivity

Scientists design smart paper capable of detecting water, conducting electricity

A fast reactor system to shorten the lifetime of long-lived fission products

France backtracks on nuclear power reduction target

AREVA NP introduces FORERUNNER robot to optimize steam generator inspections

Nuclear energy programs may not increase likelihood of proliferation

Improving sensor accuracy to prevent electrical grid overload

Japan faces challenges in cutting CO2, Moody's finds

IEA: An electrified world would cost $31B per year to achieve

'Fuel-secure' steps in Washington counterintuitive, green group says

US imposes anti-dumping duties on Chinese hardwood plywood

Peace brings hope for Colombia's biodiversity: Santos

Police detain protesters in primeval forest dispute

UN's number two accused in Chinese scam to import Nigerian rosewood

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement