Artist’s illustration of light hitting a cadmium–selenide nanocrystal (centre of image) and an electron (small yellow dot) being transferred to the nickel catalyst (molecule with large blue sphere). This is subsequently used to produce hydrogen (grey diatomic molecules).
(Courtesy: Ted Pawlicki, University of Rochester)

Nanocrystals produce hydrogen using sunlight

Nov 9, 2012

Researchers in the US have made hydrogen fuel using just sunlight, nanocrystals and a cheap nickel catalyst. The new artificial photosynthesis process is the first of its kind to continually produce fuel for several weeks without slowing down. As a result it could be important for green-energy applications and also for certain industrial processes such as those for producing ammonia.

During photosynthesis, plants harness solar radiation and convert it into energy. Most artificial photosynthesis systems try to mimic this natural process by exploiting light-absorbing dye molecules called chromophores to split water into hydrogen and oxygen. The hydrogen is produced in the reductive side of the reaction and the oxygen in the oxidative side. These so-called half-reactions are part of the process that converts light into energy, but the problem is that such technologies are inefficient and short-lived because the Sun’s rays damage and destroy the light-absorbing dyes in just a few hours.

Now, a team of researchers led by Todd Krauss, Patrick Holland and Richard Eisenberg at the University of Rochester has developed a new photochemical hydrogen-generating system made of cadmium–selenide (CdSe) quantum dots, nickel salt catalysts and ascorbic acid (vitamin C). The system lasts for several weeks rather than just hours and, in water, has an efficiency of 36% for converting solar power into energy. If the surrounding solution is a mix of water and ethanol, this efficiency increases to 66%. Such high values have never yet been observed for such all-solution-based systems. The only snag is that the vitamin C (which acts as an electron donor) gets used up and regularly needs to be replenished during each hydrogen production cycle.

Read more: Nanocrystals produce hydrogen using sunlight – Physics World.

Home           Top of page