This ‘two-faced’ membrane can create electricity—from nothing but salty water
27th October 2018
When ionic salts, made of bundles positively and negatively charged particles, dissolve in water, the bundles break apart, leaving positively and negatively charged particles free to participate in osmosis. By placing charged, thin membranes in between salty water and freshwater, scientists can create an expressway for the flowing particles, generating electric current. But these membranes are often expensive to manufacture and they tend to get leaky over time. That lets particles pass back through in the wrong direction, cutting into how much electricity they can produce.
Now, researchers have developed a new kind of gatekeeper—a “two-faced” membrane that has different properties on either side, from the size of the pores to the charge of the membrane itself. This encourages a steady flow of charged particles from one side to the other while preventing them from drifting back in the wrong direction. These so-called Janus membranes, named after the ancient Roman god of gates and passages, can also be manufactured to have different-size pores and hold different charges, allowing them to accept different kinds of particles.