Scientists say new nanomaterial can harness sunlight to produce hydrogen for green energy

Inspired by photosynthetic bacteria, international team develops material that uses light to convert water into hydrogen for fuel cells
It can be used in fresh and salt water under ambient conditions, potentially increasing efficiency and decreasing costs of process, they say

Science

Holly Chik

Published: 9:00am, 19 Jun 2023

Why you can trust SCMP

An international team of scientists developed a new nanomaterial to extract hydrogen from water in a solar-powered process that could open the door to green and efficient clean energy production.

The researchers said the material could be used in both fresh water and salt water under ambient conditions without the need for specific temperatures or pressure levels.

Hydrogen is regarded as the ultimate non-polluting fuel and the energy-storage medium of the future. A conventional way to produce hydrogen is to split water into oxygen and hydrogen using electricity in a process called electrolysis.

To eliminate the need for electricity in the process, scientists in Britain, Canada, Hong Kong, mainland China and the United States took inspiration from nature.

Plants perform photosynthesis, the process of using sunlight, water and carbon dioxide to create oxygen and energy in the form of sugar. Similarly, there are photosynthetic bacteria that can efficiently transfer energy from sunlight.

In a study published in Nature Catalysis on May 18, the scientists mimicked the bacteria’s unique structure, which acts as a light sensor, to create the nanomaterial.

The nanomaterial serves as the building blocks of an artificial system that can harness light for photocatalysis, a chemical reaction activated by light energy that produces hydrogen and other substances.

The team’s process uses light to convert water into hydrogen for use in fuel cells and industrial products such as methanol and aldehyde.

The team has published other findings from their years-long project in peer-reviewed journals including Energy and Environmental Science and Nature Communications.

08:42

The surprising hurdle slowing China’s switch to green energy

Lead scientist David Lee Phillips, professor and chair of physical chemistry at the University of Hong Kong, said the team’s next step would be to build photocatalysis tool kits that could change carbon dioxide into useful and beneficial substances.

He said being able to deploy the nanomaterial in ambient conditions was a breakthrough in solar energy conversion research.

“The nanomaterial is stable enough in ambient water. That’s a big breakthrough because a lot of things for photocatalysis reactions are not necessarily stable in water. Here we’re using water as the reactant – kind of like what nature does,” he said.

He added that if catalysis could be performed at ambient temperatures, it could be done more efficiently and cheaply because it did not require a lot of energy or complex equipment to control temperature or pressure.

Guo Zhengxiao, a joint-faculty professor of chemistry and mechanical engineering at HKU who leads the solar-hydrogen research in collaboration with Phillips, said another advantage of the nanomaterial system was that it could turn out high-purity products.

“In industry, we want things which are pure. We want pure hydrogen, but not other stuff like ammonia or hydrocarbon because impurities degrade devices like fuel cells,” he said, adding that a membrane could be used to further filter out unwanted molecules.

“Together, this technology can make a real green and cost-effective selective process to produce particular products,” he said.

Earlier this month, a team of Chinese scientists successfully converted seawater into hydrogen and oxygen without the need for desalination on a floating hydrogen farm. The offshore platform in southeastern China harnessed both wind and solar power.

Phillips said the Chinese team’s project was a test pilot for the green generation of hydrogen.

“What we try to do is offer ways of doing it very efficiently with the new system and hopefully it can be tested and integrated into practical applications,” he said.

He added that the new material could boost the efficiency of hydrogen production while making it more robust so the solar panels and other devices involved could last longer.