Laser-induced graphene electrode splits water into hydrogen and oxygen


Laser induced graphene

Chemists have produced a catalyst based on laser-induced graphene that splits water into hydrogen and oxygen. They said the inexpensive material may be a practical component in generating the hydrogen for use in future fuel cells.

The fabricated material developed by the Rice lab of chemist James Tour offers a robust and efficient way to store chemical energy. Tests showed the thin catalyst producing large bubbles of oxygen and hydrogen on either side simultaneously.

Hydrogen currently made by converting natural gas to a mixture of carbon dioxide and hydrogen gas, Tour said. For every two hydrogen molecules, a molecule of carbon dioxide is formed, making this traditional process a greenhouse-gas emitter.

The catalyst used for versatile laser-induced graphene (LIG), which introduced in 2014. LIG is produced by treating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms. LIG, a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

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electrochemical deposition

The Rice material uses only a quarter of the platinum found in commercial catalysts. The other side, for oxygen evolution, first turned into LIG and then enhanced with nickel and iron through electrochemical deposition. Both sides showed low onset potentials and strong performances over 1,000 cycles.

Also, making the polyimide into an LIG catalyst with cobalt and phosphorus that could replace either the platinum or nickel-iron sides to produce hydrogen or oxygen. While, the low-cost material benefits of eliminating expensive noble metals, it sacrifices some efficiency in hydrogen generation.

When configured with cobalt-phosphorus for hydrogen evolution and nickel-iron for oxygen, the catalyst delivered a density of 10 milliamps per square centimeter at 1.66 volts. It increases 400 milliamps per square centimeter at 1.9 volts without degrading the material. The current density governs the rate of the chemical reaction.

The enhanced LIG offers water-splitting performance that’s comparable and often better than many current systems. The material also serves as the basis for efficient electro catalysis platforms for carbon dioxide or oxygen reduction.

More information: [ACS Applied Materials and Interfaces]