Japan develops solar conversion to hydrogen

 Spectrum:

Converting sunlight into hydrogen is a seemingly ideal way to address the world’s energy challenges. The process doesn’t directly involve fossil fuels or create any greenhouse gas emissions. The resulting hydrogen can power fuel-cell systems in vehicles, ships, and trains; it can feed into the electrical grid or be used to make chemicals and steel. For now, though, that clean energy vision mainly exists in the lab.

Recently, Japanese researchers said they’ve made an important step toward making vast amounts of hydrogen using solar energy. The team from Shinshu University in Nagano studies light-absorbing materials to split the hydrogen and oxygen molecules in water. Now they’ve developed a two-step method that is dramatically more efficient at generating hydrogen from a photocatalytic reaction.

The researchers began with barium tantalum oxynitride (BaTaO2N), a semiconductor material that can absorb light at up to 650 nanometers (a visible wavelength at the orange end of red). The powdery substance serves as the photocatalyst, harnessing solar energy needed to drive the reaction. They also used an aqueous methanol solution instead of water, which allowed them to focus only on the hydrogen component and reduce the complexity of the reaction.

By itself, BaTaO2N can hardly “evolve” hydrogen gas from the solution. So, using their new method, the Shinshu team “loaded” the powder granules with a platinum-based co-catalyst to improve the chemical activity.

As a result, the materials evolved hydrogen much more efficiently—about 100 times more efficiently—than BaTaO2N that’s been loaded with platinum using conventional methods, according to their paper in the journal Nature Communications.
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Solar energy experts have called efforts to make hydrogen more easily or efficiently a “Holy Grail quest.” When used in fuel-cell-powered vehicles or buildings, the odorless gas doesn’t produce emissions or air pollution—just a little heat and water. However, nearly all hydrogen today is made using an industrial process that involves natural gas, which ultimately pumps more emissions into the atmosphere. A handful of facilities can make “green” hydrogen using renewable electricity to split water molecules, but the process itself is energy-intensive. If scientists can directly make hydrogen from the sun’s energy, they could bypass this expensive step.
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While this is an interesting development it is apparently not one that is ready for commercial development.  The article does not indicate what the cost of the catalyst used would be or the cost of the resulting hydrogen.  Platinum is not a cheap material.