New screening system may point the way to clean, renewable hydrogen
power

Date:
February 28, 2022
Source:
Penn State
Summary:
A new, highly sensitive system for detecting the production of
hydrogen gas may play an important role in the quest to develop
hydrogen as an environmentally friendly and economical alternative
to fossil fuels.



FULL STORY ==========================================================================
A new, highly sensitive system for detecting the production of hydrogen
gas may play an important role in the quest to develop hydrogen as an environmentally friendly and economical alternative to fossil fuels,
according to Penn State scientists.


==========================================================================
"We have built a new system for detecting hydrogen evolution that is
the most sensitive in the world," said Venkatraman Gopalan, professor
of materials science and engineering and physics at Penn State. "This
tackles a problem that had not been addressed but that is important
going forward for materials discovery." The tool can be used to
screen promising photocatalysts, materials that when placed in water
and exposed to sunlight facilitate reactions that split water molecules
into hydrogen and oxygen gases, the scientists said. The process, called
water splitting, offers a clean and renewable source of hydrogen, but
it is inefficient and finding the right photocatalysts to boost hydrogen production has been challenging.

In a study, the team found they could test smaller amounts of
photocatalyst material than previously possible and detect very small
amounts of hydrogen gas produced, or hydrogen evolution, in the range
of tens of nanomoles per hour per tens of milligrams of material. They
recently published their findings in the Review of Scientific Instruments.

"If you ranked low in both the categories of hydrogen evolution rate
and the mass of the photocatalyst needed, it means it's a really
sensitive system for discovering new photocatalytic materials," said
Huaiyu "Hugo" Wang, a graduate student in the Department of Materials
Science and Engineering who led the study and built the system. "And
it turns out that our work ranked the best in both categories."
Developing photocatalysts is an area of intense research. At Penn State, scientists led by Ismaila Dabo, associate professor of materials science
and engineering, recently used a supercomputer to narrow a list of more
than 70,000 different compounds down to six promising candidates. Another
team led by Raymond Schaak, DuPont Professor of Materials Chemistry, synthesized the materials in their laboratory, but creating even small
amounts is expensive and time consuming.



========================================================================== "Typical photocatalysts use rare and precious metals such as platinum,
which are immensely expensive," said Julian Fanghanel, a graduate
student in materials science and engineering who is co-advised by
Dabo and Schaak. "For this project, we are making dozens of samples
of materials, so making them in large quantities is impractical,
time- consuming and costly." Gopalan said the new system will allow
scientists to test smaller amounts of these materials and focus efforts
on the most promising candidates. But when it came time to test samples,
the researchers found commercial equipment was not sensitive enough,
so Gopalan and Wang built their own.

"They developed from the ground up a uniquely sensitive gas chromatography setup for the reproducible detection of hydrogen, which was instrumental
to the validation of our computational predictions," Dabo said. "This
newly developed capability was a key enabler to confirm the discovery of
new photocatalysts for the solar production of hydrogen." Unlike the commercial units, the new design can test photocatalysts in their bare
state, the scientists said. To be effective, photocatalysts require co- catalysts and other techniques that further improve their efficiency. The
gold standard, for example, is titanium dioxide with platinum particles
added as a co-catalyst. Photocatalysts without these add-ons are
considered bare.

"When we are looking at new materials, we don't know what the correct
co- catalysts will be," Wang said. "The simple answer is -- detecting
the bare form is the quickest way to help guide the direction of this
materials discovery process." Two of the photocatalyst materials tested
as part of the study performed better than titanium dioxide did in its
bare state, the scientists said. The findings suggest that further study
of those materials could yield promising photocatalysts.



==========================================================================
"If you have a bare compound that behaved much better than titanium
dioxide then we know this is a potential material to optimize," Wang
said. "If we find the right co-catalysts for those materials, we can
improve them by orders or magnitude and these materials could eventually
be useful in water splitting." The scientists said the system is
affordable and easy to build from commercially available components. It features a low leakage rate and a small reaction chamber volume size,
which allows three orders of magnitude higher detection sensitivity for hydrogen evolution than a conventional gas chromatography system.

"It's not a brand new technology, it's just superior engineering," Gopalan said. "The value of this is that it's a simple, cost-effective system
that anyone can build. And if they do, their research for discovering new photocatalysts is going to go much faster." Also contributing from Penn
State was Rebecca Katz, graduate student in the Eberly College of Science.

The National Science Foundation supported this research.

========================================================================== Story Source: Materials provided by Penn_State. Original written by
Matthew Carroll. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Huaiyu(Hugo) Wang, Rebecca Katz, Julian Fanghanel, Raymond
E. Schaak,
Venkatraman Gopalan. Ultrasensitive electrode-free and
co-catalyst-free detection of nanomoles per hour hydrogen evolution
for the discovery of new photocatalysts. Review of Scientific
Instruments, 2022; 93 (2): 025002 DOI: 10.1063/5.0077650 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220228172040.htm

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