In a time when clean drinking water remains a privilege rather than a guarantee for billions, a promising scientific breakthrough offers a glimpse of hope — drawn quite literally from thin air.
An international team of researchers has unveiled a novel nanomaterial designed to extract potable water directly from water vapour in the atmosphere.
Thie new material, remarkably, can absorb more than three times its own weight in water and does so significantly faster than current commercial technologies. Such performance could pave the way for practical, scalable solutions to transform humidity into drinkable water, even in arid regions.
This pioneering effort is spearheaded by the Australian Research Council Centre of Excellence for Carbon Science and Innovation (ARC COE-CSI), under the leadership of Associate Professor Rakesh Joshi of UNSW Sydney and Nobel Laureate Professor Sir Kostya Novoselov from the National University of Singapore.
While the technology itself is impressive, its context underscores its urgency. According to the United Nations, 2.2 billion people still lack access to safely managed drinking water — a sobering statistic in an age of remarkable technological progress.
Yet, hidden in plain sight above us is an untapped reservoir: Earth’s atmosphere holds about 13 million gigalitres of water vapour. To put that in perspective, Sydney Harbour, an iconic body of water, contains just 500 gigalitres.
If the promise of the nanomaterial can be translated into cost-effective, deployable devices, communities around the world could someday draw clean water from the air, alleviating the daily hardship faced by millions and fortifying resilience against drought and climate uncertainty.
“Our technology will have application in any region where we have sufficient humidity but limited access to or availability of clean potable water,” Dr Joshi says.
Prof Novoselov says, “This is an excellent example of how interdisciplinary, global collaboration can lead to practical solutions to one of the world’s most pressing problems—access to clean water.”
The novel nanomaterial is based on the well-studied form of the graphene oxide, which is a single atom thick carbon lattice functionalised with oxygen containing groups. Graphene oxide has good water adsorption properties, which are properties that enable water to bond to the surface of a material.
Calcium also has good water adsorption properties. The research team decided to see what happened if you intercalate calcium ions (Ca2+) into the graphene oxide.
An important characteristic of materials that effectively adsorb water is strong hydrogen bonds between the water and the material it adsorbs onto, something that graphene oxide and calcium each have. The stronger the hydrogen bond, the more a material can adsorb water.
But some magic happens when you intercalate calcium to the oxygen in the graphene oxide. In calcium-intercalated graphene oxide, it is the synergy between calcium and oxygen that facilitates the extraordinary adsorption of water.
What the research team discovered is that the way the calcium coordinates with the oxygen in the graphene changes the strength of the hydrogen bonds between the water and the calcium to make those bonds even stronger.
“We measured the amount of water adsorbed onto graphene oxide by itself and we measured X. We measured the amount of water adsorbed onto calcium itself and we got Y,” said Xiaojun (Carlos) Ren, UNSW School of Materials Science and Engineering and first author on the paper.
“When we measured the amount of water adsorbed onto the calcium-intercalated graphene oxide we got much more than X+Y. Or it is like 1+1 equals a number larger than 2,”
“This stronger than expected hydrogen bonding is one of the reasons for the material’s extreme ability to adsorb water,” Ren said.
It’s also light as a feather
There was one more design tweak the team did to enhance the material’s water adsorbing ability – they made the calcium-intercalated graphene oxide in the form of an aerogel, one of the lightest solid materials known.
Aerogels are riddled with micro- to nanometre-sized pores giving them a massive surface area, which helps this aerogel form adsorb water far quicker than the standard graphene oxide.
The aerogel also gives the material sponge-like properties that make the desorption process, or release of the water from the membrane, easier.
“The only energy this system requires is the small amount needed to heat the system to about 50 degrees to release the water from the aerogel,” says Prof Daria Andreeva, the co-author of the paper.
Harnessing Supercomputer Power
The research is based on experimental and theoretical work that relied on the Australian National Computational Infrastructure (NCI) supercomputer in Canberra.
Professor Amir Karton from the University of New England led the computational work to provide the crucial understanding of the underlying mechanism.
“The modelled simulations done on the supercomputer explained the complex synergistic interactions at the molecular level, and these insights now help to design even better systems for atmospheric water generation,” said Prof Karton.
When Science Knows No Borders
This is still a fundamental research discovery that needs further development. Industry have collaborated on this project to help scale up this technology and develop a prototype for testing.
“What we have done is uncover the fundamental science behind the moisture adsorption process and the role of hydrogen bonding,” said COE-CSI Director and one of the coauthors on the paper, Prof Liming Dai.
“This knowledge will help provide clean drinking water to a large proportion of those 2.2 billion people that lack access to it, demonstrating the societal impact by collaborative research from our Centre,” he said.
The research represents a truly global collaboration, bringing together leading scientific minds and research groups from Australia, China, Japan, Singapore, and India
