Nav: Home

Finding the right balance for catalysts in the hydrogen evolution reaction

June 27, 2018

Tsukuba, Japan--Hydrogen produced from water by the hydrogen evolution reaction is an attractive clean fuel source. Production of hydrogen on a large scale at low cost is necessary to realize its viability as an alternative energy source to fossil fuels. To achieve this goal, durable, inexpensive catalysts are required. Most present catalysts based on non-precious metals suffer from instability in the acidic solutions formed during hydrogen evolution. However, simply protecting the catalyst from the acidic solution tends to lower its activity.

A collaboration led by the University of Tsukuba has recently optimized an approach to increase the stability of catalysts used in the hydrogen evolution reaction without markedly sacrificing activity. The team found that coating catalyst nanoparticles with an optimal number of layers of graphene--a sheet of carbon atoms organized into a honeycomb lattice with high conductivity and mechanical strength--raised nanoparticle durability while allowing the nanoparticles to retain their catalytic activity. The study was reported in ACS Energy Letters.

"We optimized the balance between the number of graphene layers coating the nanoparticles and their catalytic activity," study first author Kailong Hu says. "To do this, we had to precisely control the number of graphene layers coating the nanoparticles, which we achieved by carefully regulating the deposition time of graphene on the nanoparticles."

A series of nanoparticle samples coated with different numbers of graphene layers was fabricated, characterized, and then their catalytic activity in the hydrogen evolution reaction was determined. The catalyst nanoparticles coated with the optimal number of graphene layers, which was just three to five layers, displayed similar activity in the hydrogen evolution reaction to that of an expensive platinum-based catalyst. Importantly, these nanoparticles also exhibited high stability; the graphene coating prevented the metal nanoparticles from dissolving in the acidic reaction solution.

The researchers conducted theoretical calculations to support their experimental findings. The results corroborated the relationships between graphene layer number, chemical stability, and catalytic activity of the nanoparticles indicated by the experimental data. That is, the nanoparticles coated with less than three graphene layers showed higher catalytic activity than those coated with three to five layers but this came at the expense of durability; the former showed poorer chemical stability than the latter.

"Our results pave the way for rational design of stable, cheap catalysts for large-scale hydrogen production at hydrogen stations by on-site polymer electrolyte membrane electrolysis under acidic conditions," co-author Yoshikazu Ito explains.

The team's findings bring us a step closer to the realization of a clean sustainable future using hydrogen as a fuel source.
-end-


University of Tsukuba

Related Graphene Articles:

Graphene: The more you bend it, the softer it gets
New research by engineers at the University of Illinois combines atomic-scale experimentation with computer modeling to determine how much energy it takes to bend multilayer graphene -- a question that has eluded scientists since graphene was first isolated.
How do you know it's perfect graphene?
Scientists at the US Department of Energy's Ames Laboratory have discovered an indicator that reliably demonstrates a sample's high quality, and it was one that was hiding in plain sight for decades.
Graphene is 3D as well as 2D
Graphene is actually a 3D material as well as a 2D material, according to a new study from Queen Mary University of London.
Conductivity at the edges of graphene bilayers
For nanoribbons of bilayer graphene, whose edge atoms are arranged in zigzag patterns, the bands of electron energies which are allowed and forbidden are significantly different to those found in monolayer graphene.
How to purify water with graphene
Scientists from the National University of Science and Technology 'MISIS' together with their colleagues from Derzhavin Tambov State University and Saratov Chernyshevsky State University have figured out that graphene is capable of purifying water, making it drinkable, without further chlorination.
Decoupled graphene thanks to potassium bromide
The use of potassium bromide in the production of graphene on a copper surface can lead to better results.
1 + 1 does not equal 2 for graphene-like 2D materials
Physicists from the University of Sheffield have discovered that when two atomically thin graphene-like materials are placed on top of each other their properties change, and a material with novel hybrid properties emerges, paving the way for design of new materials and nano-devices.
Graphene's magic is in the defects
A team of researchers at the New York University Tandon School of Engineering and NYU Center for Neural Science has solved a longstanding puzzle of how to build ultra-sensitive, ultra-small electrochemical sensors with homogenous and predictable properties by discovering how to engineer graphene structure on an atomic level.
Graphene on the way to superconductivity
Scientists at HZB have found evidence that double layers of graphene have a property that may let them conduct current completely without resistance.
A human enzyme can biodegrade graphene
Graphene Flagship partners discovered that a natural human enzyme can biodegrade graphene.
More Graphene News and Graphene Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab