A novel molybdenum-coated catalyst that can efficiently split water in acidic electrolytes is developed by researchers at KAUST and could help with efficient production of hydrogen.
When burned, hydrogen is converted into water and heat to make an entirely clean power source. Thus, in the quest for greener power, there is an urgent need for a sustainable and efficient means of producing it. One way is to split water using a process known as photocatalytic hydrogen evolution: water molecules are split into hydrogen and oxygen using only sunlight to provide the necessary energy. In this sense, hydrogen acts as a means of storing solar energy.
A high-resolution electron microscope image (right) of the platinum electrocatalytic layer coated with molybdenum. The platinum catalyzes the hydrogen-evolution reaction (left) in acidic medium from protons in the electrolyte while the molybdenum layer inhibits water-forming reactions.
Credit: © 2017 KAUST
Scientists are searching for ways of improving this water-splitting reaction by developing an optimal catalyst. While many different materials have been tried, they are usually adversely affected by the oxygen that is also created alongside the hydrogen during the process. The two gaseous products can easily recombine back to water due to reverse water-forming reactions, hindering the production of hydrogen.
Angel Garcia-Esparza and Tatsuya Shinagawa--two former KAUST Ph.D. students as leading researchers supervised by Associate Professor of Chemical Science Kazuhiro Takanabe--collaborated with other colleagues from the Catalysis Center and other specialists in the University to create a hydrogen-evolution reaction catalyst that is both acid-tolerant and selectively prevents the water-reforming reaction1.
"The development of acid-tolerant catalysts is an important challenge because most materials are not stable and quickly degrade in the acidic conditions that are favorable for hydrogen generation," says Garcia-Esparza.
Because the acidity of the solution was crucial for the stability of the material, the team took the time to establish the optimal pH level between 1.1 and 4.9. They then electro-coated molybdenum onto a standard platinum electrode catalyst in a mildly acidic solution.
Comparing the performance of the photocatalyst with and without the molybdenum coating, the team showed that without molybdenum the rate of hydrogen production eventually plateaued after 10 hours of operation under illumination by ultraviolet light. However, the introduction of molybdenum prevented this fall in performance. The researchers believe that this is because the molybdenum acts as a gas membrane, preventing oxygen from reaching the platinum and disrupting its catalytic performance.
"The main challenge for most catalysts is the long-term stability of the materials" explained Garcia-Esparza. "So it is an important step to have an acid-tolerant material capable of preventing the water-forming back reaction that slows down water splitting."
"Nevertheless, we are still far from a commercial device and more work needs to be done," said Garcia-Esparza.
Michelle D'Antoni | EurekAlert!
Electrical fields drive nano-machines a 100,000 times faster than previous methods
19.01.2018 | Technische Universität München
ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records
16.01.2018 | Institut für Solarenergieforschung GmbH
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy