Carbon-based sensors to spot toxins

Nanoporous crystals, made using carbon nitrides with high nitrogen content, can be used as catalysts to generate hydrogen from water and to make sensors for detecting toxic acids¹.

Carbon nitrides are hailed for their thermal conductivity, semiconducting nature and biocompatibility, but their potential remains largely untapped due to their low nitrogen content.

“This is the first report on the synthesis of high nitrogen-containing nanoporous carbon nitride that can split water into hydrogen and oxygen by harnessing the energy of visible light,” says lead scientist Ajayan Vinu from the University of South Australia, Adelaide. The research team includes scientists from SABIC Corporate Research and Development Center at KAUST, Thuwal, Saudi Arabia, and the National Institute for Materials Science, Ibaraki, Japan. 

The nitride catalyst’s main perk is its relatively higher hydrogen production from water, a process that increases with prolonged exposure to light.

Its hydrogen production is tied to high nitrogen content that modifies its chemical structure, resulting in a low-energy band gap — a feature that helps generate light-induced electric currents.  

Detailed analysis shows that the catalyst can absorb visible light just like a semiconductor. Photons captured from light scatter through its pores, exciting the catalyst’s atoms, and causing them to release electrons which are then transported to the surface. The current generated splits water molecules into hydrogen and oxygen. 

The catalyst also shows higher sensitivity towards harmful acids such as formic acid and acetic acid, suggesting its potential for use as a sensor. 

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