doi:10.1038/nindia.2017.66 Published online 12 June 2017
Researchers have synthesized carbon-nitride-based nanoporous crystals that can be used as a catalyst to split water into hydrogen and oxygen, and to make sensors for detecting toxic chemicals1.
Carbon nitrides are well known for their thermal conductivity, semiconducting ability and biocompatibility, but due to low nitrogen content their potential remains largely unexplored.
Scientists from the Bhabha Atomic Research Centre in Mumbai along with colleagues from Australia and Saudi Arabia prepared carbon nitrides with a high nitrogen content. They then investigated he catalytic and sensing properties of carbon nitrides’ in splitting water and sniffing out toxic chemicals.
The nitride catalyst’s hydrogen production is attributed to its high nitrogen content that modifies its chemical structure, resulting in a low-energy band gap — a feature that helps generate light-induced electric currents. This, in turn, enhanced its efficiency in splitting water into hydrogen and oxygen by absorbing visible light, a process that increased with prolonged exposure.
The catalyst showed an ability to 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.
When exposed to a mix of toxic chemicals including organic acids, the catalyst showed higher sensitivity towards harmful acids such as formic acid and acetic acid, suggesting its potential for use as a sensor.
1. Mane, G. P. et al. Highly ordered nitrogen-rich mesoporous carbon nitrides and their superior performance for sensing and photocatalytic hydrogen generation. Angew. Chem. Int. Ed. (2017) doi: 10.1002/anie.201702386