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Photocatalytic nanomaterials are widely used for removing pollutants from the air, wastewater and the walls of buildings. When exposed to ultraviolet (UV) light, these materials catalyse the decomposition of water to give hydroxyl radicals. These strongly oxidizing molecules can subsequently react with many different pollutants, which is usually the first step in their removal from the environment.
Photocatalysts should ideally be stable, inexpensive, and non-toxic. Alternatives to metal oxides are often required to achieve these desired goals. Silicon carbide (SiC) nanostructures are promising candidates because they are wide bandgap semiconductors with large surface areas and they absorb solar energy very efficiently. However, the photocatalytic properties of SiC nanostructures are not well understood.
Now, Weimin Zhou and colleagues1 of the Shanghai Jiao Tong University, China, have synthesized 8–20-nm diameter, cubic silicon carbide (
-SiC) nanowires encapsulated in silicon oxide. The SiC nanowires were shown to accelerate the decomposition of acetaldehyde — a small organic compound — under UV irradiation. The nanowires coated with an oxide layer showed higher photocatalytic activity than those without because of enhanced adsorption of gaseous acetaldehyde by the oxidized wires. Semiconducting SiC nanowires offer an alternative to titanium and other metal oxides for use in smart nano-electronics for environmental control and monitoring. 