Splitting the water molecule: Sino-Japanese scientists mimic plants to solve energy problems

PUBLISHED : Wednesday, 17 June, 2015, 8:01am
UPDATED : Thursday, 08 March, 2018, 6:04pm

Taking inspiration from the way in which plants produce hydrogen using energy from the sun, scientists in China and Japan claim to have discovered a new formula for making a do-it-yourself “gas field” at home that could provide electricity and fuel for the house and car. 

Theoretically, users could throw a handful of the new compound into their backyard swimming pool and use the fuel produced to fill up their tanks, without requiring a trip to the petrol station.

Scientists see this as a potential breakthrough for energy production, in an age when people are becoming increasingly conscious of the earth’s limited resources while slowly migrating over to cleaner energy sources.

“The beauty of this technology is that it can be used by anybody at any place using water and sunlight, without the need for massive infrastructure or financial investment,” said professor Zhang Fuxiang, a lead scientist of the study.

“If you don’t have a swimming pool, that’s fine. Just lift a few buckets of water on the roof and the power created will generate enough hydrogen to meet your daily energy needs. It’s as simple and cheap as this,” added Zhang, who works for the Chinese Academy of Sciences’ Dalian Institute of Chemical Physics. 

The breakthrough was reported in the latest issue of Angewandte Chemie, a leading peer-reviewed journal on applied chemistry in Germany.

Researchers from Dalian, capital of China’s northern Liaoning province, and Tokyo stumbled upon a new type of photo-catalyst that can separate the oxygen and hydrogen found in water molecules as efficiently as plants do when exposed to sunlight. 

“This is the most powerful water-splitting powder ever made,” Zhang said.

“It is difficult to predict when this could go into mass production, but if the research progresses at its current pace and momentum, you can expect the first product to hit shelves within a decade,” he added. 

The sun produces photons that contain kinetic energy. The energy created is powerful enough to cut the bond between the two elements found in water molecules. 

In order for the two elements to be separated, a photon must hit the water molecule at exactly the right time and place, thus causing the electrons to flow in the correct direction. The chances of this happening randomly are extremely remote. 

For decades, scientists have marveled at the way in which plants were able to split water, as part of the process of photosynthesis during which they convert sunlight into chemical energy. Many have tried to mimic this process, but it has been an ongoing journey of discovery.

Scientists are interested in producing hydrogen from water because it can be burned as an absolutely clean form of fuel, or converted directly to electricity using fuel cell technology. 

During the photosynthetic process, plants harvest hydrogen from water and use it to bind with carbon dioxide to produce glucose, a simple sugar that is an important energy source in living organisms and is a component of many carbohydrates.

“The working mechanism of our powder is almost the same as that of a plant,” Zhang said. “The major challenge is being able to catch the rapidly moving electrons [a preliminary step to splitting the elements in water], which plants do very well.” 

To make the process sustainable, researchers developed a catalyst in the form of powder using a range of materials with different physical and chemical functions. The materials included tantalum, magnesium, nitrogen and oxygen. 

The powder proved as good at splitting water as a plant. In technical terms, it achieved an apparent quantum efficiency of 6.8 per cent under visible light.

This unprecedented level of efficiency suggested a promising solution to mankind’s energy problems, Zhang said. 

In the past few years, the efficiency of water-splitting technology has jumped nearly 20 times. But even the latest development is not far enough ahead to generate enough hydrogen to meet practical needs. 

The rate of efficiency would have to increase at least another 10-fold for it to be a realistic alternative to fossil fuels, the team said. 

Improvements in nano technology facilitated the breakthrough by allowing the scientists to design and put together functional materials with greater ease.

However, they struggled due to an “unstable” stream of government funding, Zhang said, adding that this was affected by falling oil prices and an increase in the supply of fossil fuels like natural gas.