Engineering Services

Researchers Find New Way to Produce Clean Hydrogen Fuel from Water with the Sun

04 October 2017

Hydrogen is one of the most abundant elements and is considered by many people to be a potential clean fuel of the future. Water and fossil fuels contain a lot of hydrogen, but unlocking molecular dihydrogen fuel from these sources takes a lot of energy, which is making some people doubtful of any future hydrogen economy. Turning water into hydrogen with solar could lead the way to cheap and clean hydrogen fuel. This process currently relies on photocatalysts that contain expensive precious metals that limit its capacity.

Transmittance electron microscopic image of the composite photocatalyst with two components, black phosphorous (BP) and graphitic carbon nitride (g-C3N4). Source: Osaka UniversityTransmittance electron microscopic image of the composite photocatalyst with two components, black phosphorous (BP) and graphitic carbon nitride (g-C3N4). Source: Osaka University

Researchers at Osaka University have developed a new kind of photocatalyst for producing hydrogen from water. This method is free of expensive metals and absorbs a wider range of sunlight than before.

"We were pleased to find a good amount of hydrogen produced from water using our new composite photocatalyst with graphitic carbon nitride and black phosphorous," lead author Tetsuro Majima said. "But what we didn't expect to find was that even when using low-energy light, in the near infrared, the photocatalyst continued to produce hydrogen."

Just like graphite, graphitic carbon nitride forms in large sheets, but carbon nitride sheets have holds that can interact with hydrogen molecules. In the past, photocatalysts based on carbon nitride have needed help from precious metals to produce hydrogen from water. The researchers found the metal could be replaced by a kind of phosphorous that is widely abundant and inexpensive.

Their photocatalyst was effective for producing hydrogen from water with energy from different kinds of light. Most unusually, even near-infrared light with low energy could drive the hydrogen production.

Studies of the working photocatalyst in the picosecond time scale revealed that strong interactions between the carbon nitride and black phosphorous in the composite promoted hydrogen production. When the two materials were tested separately, the energy from the sunlight was rapidly dissipated and little or no hydrogen produced.

Majima says, "The hydrogen economy faces a great many challenges, but our work demonstrates the potential for efficiently and cheaply producing hydrogen from water with a photocatalyst based on widely abundant elements. This is an important step toward making other hydrogen-based technologies economically and environmentally viable."

A paper on this research was published in the Journal of the American Chemical Society.

To contact the author of this article, email Siobhan.Treacy@ieeeglobalspec.com


Powered by CR4, the Engineering Community

Discussion – 3 comments

By posting a comment you confirm that you have read and accept our Posting Rules and Terms of Use.
Re: Researchers Find New Way to Produce Clean Hydrogen Fuel from Water with the Sun
#1
2017-Oct-04 2:28 PM

Interesting. Compare with slightly oxidized graphite material (coal). GPO structures have proven to be a "proton conduit". I even saw indirect evidence of wet graphite acting as superconductor in one report - although it was not well quantitated.

I would have thought a redox couple necessary...is sunlight doing something to the black phosphorus? What is the work function (eV) of black phosphorus for photo-electron? Is there anomalous behavior here, or "the usual chemistry"?

Why not use the readily recyclable magnesium metal?

Re: Researchers Find New Way to Produce Clean Hydrogen Fuel from Water with the Sun
#2
In reply to #1
2017-Oct-05 12:44 PM

Hmm... P is less electronegative than C (2.19 and 2.55, resp.; H and O are 2.20 and 3.44, resp.; Mg, 1.31)... I think one key factor is that black P has a similar lattice structure to C-- for nano-sheet manufacture. The P must somehow suppress energy transfer to heat, which is a major loss for electrolysis in general (this is similar to electrolysis).

As far as recycling goes, I don't know, but that consideration might not be in the scope of their research...

Re: Researchers Find New Way to Produce Clean Hydrogen Fuel from Water with the Sun
#3
In reply to #2
2017-Oct-05 1:33 PM

I saw a couple years back about I think it was Tokyo Technical Institute doing research on a magnesium economy for Japan, where magnesium reacts with vigor with warm water, to create hydrogen and steam, and the burning of hydrogen leads to more steam, or goes to fuel cell. The magnesium oxide being converted back through the usual methods of winning the alkaline earth metal.

This research is still an infant (current topic with black P).

Perhaps we will know more about actual production figures before long, and also how long the materials in solution contact will last.

Engineering Newsletter Signup
Get the Engineering360
Stay up to date on:
Our flagship newsletter covers all the technologies engineers need for new product development across disciplines and industries.
Advertisement
Advertisement

Upcoming Events

Advertisement