Nav: Home

Breaking water molecules apart to generate clean fuel: Investigating a promising material

October 17, 2019

In line with the increasing global concerns about the state of our planet, perfecting the technology for alternative energy generation has become a hot topic among researchers worldwide. Among the many techniques being investigated to generate clean energy, water splitting is a very promising one. In particular, water (H2O) can be split to obtain dihydrogen (H2) by using solar energy; this is known as photoelectrochemical water splitting. Dihydrogen can be used as clean fuel for other machines or to generate electricity, which means that improving our water-splitting techniques is a guaranteed way to reduce our carbon emissions and alleviate global warming.

How does photoelectrochemical water splitting work? In short, as shown in Fig. 1, one way to do it is to use a certain type of semiconductor material, which is called the photoanode, and connect it to a small voltage source and a metal wire, which acts as the cathode. When exposed to sunlight, water is divided into its constituting atoms on these two ends; the constituent atoms recombine to form the useful H2 and O2 as a byproduct. The crucial step here is finding stable, high-performance materials for the photoanode because the oxidation sub-step, which involves the formation of O2, is the most difficult one.

Unfortunately, most research has focused on a class of photoanodes called oxynitrides, which suffer from instability and degrade relatively quickly because they are prone to oxidize when illuminated by light. To address this issue, a team of researchers from Tokyo Tech led by Prof. Kazuhiko Maeda focused instead on another type of photoanode material, an oxyfluoride with the chemical formula Pb2Ti2O5.4F1.2. This compound does not suffer from self-oxidation due to its electronic properties.

While this oxyfluoride has been reported to be promising for many other applications, there were no studies on its photoelectrochemical performance as a photoanode for water splitting. The research team studied this compound under various lighting and applied-voltage conditions, and found that, to use it as a photoanode, it is necessary to modify its surface with other compounds. First, a layer of titanium oxide (TiO2) has to be deposited on the surface of the oxyfluoride to increase the photocurrent generated by the water-splitting reaction. Then, the performance of the photoanode can be greatly enhanced by further coating it with cobalt oxides (CoOx), which penetrate through the cracks in the TiO2 layer and promote the desired reaction. "Post-modification of the photoanode with a water-oxidation promoter has proven to be indispensable to attaining stable performance in most cases," remarks Prof. Maeda.

The researchers performed several experiments to characterize their photoanode and its performance for water splitting under a variety of conditions, such as under different types of light and different voltage and pH values (which is a measure of the acidity of water). Their results are promising (Fig. 2) and very useful to point other researchers toward the right direction. "So far, oxynitrides and similar compounds have been viewed as promising but difficult-to-handle materials for photoanodes because of their inherent instability to self-oxidation. Pb2Ti2O5.4F1.2 represents a long-awaited breakthrough in this regard," concludes Prof. Maeda. Water splitting technology may be crucial for meeting our energy needs without further harming the environment, and studies like this one are essential stepping stones to reach our goals for a greener future.

Tokyo Institute of Technology

Related Technology Articles:

Post-lithium technology
Next-generation batteries will probably see the replacement of lithium ions by more abundant and environmentally benign alkali metal or multivalent ions.
Rethinking the role of technology in the classroom
Introducing tablets and laptops to the classroom has certain educational virtues, according to Annahita Ball, an assistant professor in the University at Buffalo School of Social Work, but her research suggests that tech has its limitations as well.
The science and technology of FAST
The Five hundred-meter Aperture Spherical radio Telescope (FAST), located in a radio quiet zone, with the targets (e.g., radio pulsars and neutron stars, galactic and extragalactic 21-cm HI emission).
AI technology could help protect water supplies
Progress on new artificial intelligence (AI) technology could make monitoring at water treatment plants cheaper and easier and help safeguard public health.
Transformative technology
UC Davis neuroscientists have developed fluorescence sensors that are opening a new era for the optical recording of dopamine activity in the living brain.
Do the elderly want technology to help them take their medication?
Over 65s say they would find technology to help them take their medications helpful, but need the technology to be familiar, accessible and easy to use, according to research by Queen Mary University of London and University of Cambridge.
Technology detecting RNase activity
A KAIST research team of Professor Hyun Gyu Park at Department of Chemical and Biomolecular Engineering developed a new technology to detect the activity of RNase H, a RNA degrading enzyme.
Taking technology to the next level
Physicists from the ARC Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) developed a new hybrid integrated platform, promising to be a more advanced alternative to conventional integrated circuits.
How technology use affects at-risk adolescents
More use of technology led to increases in attention, behavior and self-regulation problems over time for adolescents already at risk for mental health issues, a new study from Duke University finds.
Hold-up in ventures for technology transfer
The transfer of technology brings ideas closer to commercialization. The transformation happens in several steps, such as invention, innovation, building prototypes, production, market introduction, market expansion, after sales services.
More Technology News and Technology Current Events

Top Science Podcasts

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

Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at