A team of University of Rochester professors may have found a way to improve the process of using light to produce hydrogen. The secret: a common metal and miniscule chunks of a semiconductor material.
Chemistry professors Richard Eisenberg, Patrick Holland, and Todd Krauss aren't the first researchers to generate hydrogen using light; that's been happening for several decades. But the other processes have largely used precious metals like platinum, which are expensive and rarer than other metals, Krauss says.
"Literally, the rarest elements on earth have been used for this," he says.
In cases where rare metals weren't used, the processes were often less efficient or didn't generate hydrogen for long, Krauss says.
The professors instead used nickel and nanocrystals of cadmium selenide: about 10,000 times smaller than the width of a hair. They dissolved the substances in water and mixed in ascorbic acid, commonly known as vitamin C, to complete the reaction.
The result: instead of generating hydrogen for several hours, the system went two weeks without hydrogen production trailing off. Krauss says the researchers only had to stop because they either ran out of ascorbic acid or space to store the hydrogen.
For decades, hydrogen has held promise as a clean fuel, one whose only byproduct is water. And that's regardless of whether it's burned in a combustion engine or used in a fuel cell to generate electricity.
But making large quantities of hydrogen is tricky. It can be made using electricity to split water molecules, but the typical industrial process involves using steam to break apart methane. The latter relies on fossil fuels and ultimately results in greenhouse gas emissions, which in some ways defeats the purpose of using hydrogen as a clean fuel.
Clean, efficient hydrogen production isn't just about powering vehicles. The gas has many applications, including the production of ammonia, which is a key component of agricultural fertilizer.