A team of chemists from UConn have created a material that holds the potential of making hydrogen capture something that is much more commercially feasible. The new material is a very important element in building a brand new generation of more affordable and light-weight hydrogen fuel cells. The new catalyst does not contain any metal and uses carbon graphene nanotubes infused with sulfur.
Hydrogen is the most plentiful element in the universe and has long held promise of becoming a source for clean energy. However, producing high-grade hydrogen is an expensive processes that requires large amounts of energy. In most cases, the amount of energy used to extract hydrogen is worth far more than the hydrogen gas it creates. In a world where we are constantly looking for more energy efficient and sustainable resources, finding a cheaper and more efficient way to capture hydrogen would help to greatly reduce the need for fossil fuels.
One of the leaders of the study, Professor Steven Suib says the team has made a material that looks pretty great. He says the results show that this particular material is very competitive with materials discussed in literature and beyond exceptional for the reactions researchers are looking for.
Currently, hydrogen production uses massive amounts of heat in order to separate hydrogen from hydrocarbons that are found in crude oil. Unfortunately, the hydrogen that comes from this production isn’t very pure. The excess amounts of byproducts left over have to be removed.
Capturing hydrogen in water is a cleaner and more sustainable solution but it has far too many limitations. Electrocatalysts involved in the process are usually made of rare earth metals, such as platinum or iridium and are very expensive. This makes the commercialization of pure hydrogen fuels a difficult dream to turn into reality.
What’s so great about the non-metal catalyst is that it offers all of the electrochemical properties that rare earth metals provide without the hefty price tag. This option also offers a stability that scientists have sought after for years.
Leaders of the study, Suib and James Rusling were aware that sulfur-infused carbon graphene nanotubes were a potential solution to create an oxygen reduction reaction. This type of reaction occurs when oxygen and hydrogen molecules are indoctrinated to water. Hydrogen gas used to power the cells passes through a catalyst, causing an oxygen reduction electrochemical reaction that not only produces energy but water as well.
Completing the reverse of that process is far more difficult on an electrochemical level. Suib says the key to success was manipulating sulfur and carbon atoms to build stable bonds and structures inside the nanotubes. They had to also be able to preserve the electrochemical potential of the tubes to directly mirror those present within rare metals.
The process that was created in the pair’s lab uses a dual doping procedure that involves sulfur and benzyl disulfide that is exposed to high levels of heat. Researches added low levels of heteroatoms of sulfur in order to maintain balance. Not enough sulfur would cause the process to fail, too much leads to instability.
Suib compares isolating hydrogen within water to separating flour and sand after they have been stirred together as one. He says the sulfur-doped nanotubes use a lot less energy during the chemical reaction process than any other process being tested today. He says materials that offer the dual properties of separating hydrogen from water and limiting the amount of oxygen inside the water is very hard to come by. He was shocked the processes ended up working out so well and is excited to see how they help future research.
The study was published in the Advanced Energy Materials journal.