Edge of discovery

New research into graphitic carbon nitride has brought a solution to water scarcity a step closer

Forward: features are independent pieces written for Mewburn Ellis discussing and celebrating the best of innovation and exploration from the scientific and entrepreneurial worlds.

In just a matter of minutes, a metal-free catalytic material created by a team of researchers from Yangzhou University, the Chinese Academy of Sciences and the University of Technology Sydney showed that it was able to disinfect water packed with pathogens, making it safe to drink. Even better, the material is a photocatalyst, which means its only power requirement to achieve this result is sunlight.

It's a discovery that has raised eyebrows and interest, and with good reason. According to the World Health Organization, 785 million people lack access to safe water, with water shortages expected to affect half of the world's population by 2025. So it's clear that getting the most out of every available drop will soon become a critical concern.

That's where edge-functionalised graphitic carbon nitride (g-C3Is14) nanosheets come in. Using these as photocatalytic disinfectants, pathogen-rich water was purified in just 30 minutes with a disinfection efficiency of more than 99.9999%.

The team has been investigating polymeric carbon nitride since 2014 and has two goals for the new material, according to Professor Guoxiu Wang, director of the Centre for Clean Energy Technology at the University of Technology Sydney: 'One is to prepare a totally metal-free photocatalyst for efficient water disinfection. The other is to fabricate photocatalytic devices, which can be applied in less-developed regions for acquiring safe drinking water.'

Why is a metal-free solution important? Metal-based materials can cause secondary pollution because they leave behind metal ions as a by-product of the process.

As part of its work, the team created water disinfection bags onto which the material was affixed. Such bags have the potential to offer a portable disinfection tool that could provide enough drinking water for four adults over the course of a day (10 U.

'However,' Wang cautions, 'there are several issues that need to be solved in order to reach the final goal. First, the absorption edge of edge-functionalised g-C3 NI, is less than 450nm, leading to low-photon usage. Improving the photon absorption of this material is crucial for further improving the photocatalytic disinfection efficiency of the material. Second, it will be critical to develop anti-bacterial fibres by incorporating this novel photocatalyst. Finally, it is essential to reduce the cost of the photocatalysts for future commercialisation.'

See a full report on the material at: bit.ly/MEF3_Material