Gallium nitride is a semiconductor commonly used in blue LEDs, but also has potential applications in the photocatalytic breakdown of toxic materials. Though GaN is known to photocatalytically decompose water into hydrogen and oxygen, there is a lack of knowledge on its power to break down harmful compounds and chemical wastes. Naoki Shimosako and Hiroshi Sakama present promising results for utilizing GaN as a photocatalyst in aiding the decay of certain hazardous solutions.

When placed in a petri dish along with GaN and radiated with ultraviolet light, methylene blue (MB) – a drug which is used to treat certain blood diseases but can be dangerous at high doses – broke down, indicating photocatalytic activity. As UV light excites the electron-hole pairs in a photocatalyst, toxic matter present on its surface is oxidized, leading to decay.

The breakdown occurred with a similar quantum efficiency as other known photocatalytic materials, and with a higher absorption coefficient.

The authors chose MB as they saw it as a good test case for this process. According to them, generally, if a photocatalyst can decompose MB, it can also decompose other organic, toxic materials. In this case, GaN was effective in helping to breakdown the compound despite the non-ideal circumstances, as the samples were not developed under the best conditions, and their quality may be improved in the future.

Based on these results, “GaN photocatalyst is expected to degrade toxic, organic compounds in water, soil and air,” especially after optimization, said Shimosako.

Source: “Quantum efficiency of photocatalytic activity by GaN film,” by N. Shimosako and H. Sakama, AIP Advances (2021). The article can be accessed at https://doi.org/10.1063/5.0035628.