Copper bismuth oxide tests represent progress towards green hydrogen

The efficient production of clean hydrogen, an important solar fuel, could be a step closer following promising tests conducted on copper bismuth oxide (CBO).

CBO is a photocathode material potentially useful in the photochemical reduction of water, also known as photocatalysis, which is a necessary aspect in the creation of solar fuels.

Rather than the sun providing us with electricity through solar photovoltaic cells, and storing the electricity in batteries, which use finite lithium and cobalt, solar fuels could directly replace the fossil fuels used in cars and steel production.

Researchers at the ARC Centre of Excellence in Exciton Science, together with collaborators in China, systematically altered the ratio of copper to bismuth in their experimental compound materials to determine if this improved or diminished performance.

Tweaking the ratio produced dramatic changes in optical band gap and crystal structure, ultimately delivering the largest photocurrent density and highest value to date for photocatalysis in CBO without an externally applied bias.

The results have been published in the Journal of Physics D: Applied Physics.

The researchers will now work to improve stability by using ultra-thin protective layers of stable oxides to prevent photocorrosion.

They will also investigate how applying co-catalyst nanoparticles to the surface may increase performance.