Study looks to ice for fabricating useful porous materials

May 3, 2017 by Craig Chandler
Xiao Cheng Zeng (left) and Chonqin Zhou. Credit: University of Nebraska-Lincoln

Discovering a way to harness ice recrystallization could enable fabrication of highly efficient materials for a range of products, including porous electrodes for batteries and transparent conducting films used to manufacture touch screens and wearable electronics.

A team of researchers from the University of Nebraska-Lincoln and the Chinese Academy of Sciences published findings on the dynamics and manipulation of ice recrystallization in the May 2 issue of Nature Communications.

Ice recrystallization is a ubiquitous process in nature. It involves growing large ice crystals at the expense of small ones, leading to an increase in the average crystal and a decrease in the total number of crystals.

An experimental research group at the Chinese institution has collaborated closely with Xiao Cheng Zeng, Chancellor's University Professor of Chemistry, and Nebraska materials researchers who investigate the properties of water and ice from a computational perspective.

The Chinese group is now using recrystallized ice as a template for synthesizing two- and three-dimensional materials with different pore sizes. Together with their Nebraska colleagues, the team has learned that ions, which are electrically charged molecules, can be used to fabricate new two- and three-dimensional structures on a wide range of other host materials. These technologically important host materials are suitable for organic electronics, catalysis and bioengineering.

"The pore size of two-dimensional and three-dimensional porous produced with our method can be easily adjusted, which is critical for practical applications," said project leader Jianjun Wang, a professor in the Institute of Chemistry at the Chinese Academy of Sciences.

"The experimental-theoretical team allows us to work out the problem beautifully because whenever we predict something, they can test it," Zeng said. "Then they can feed back some of the new experimental data, allowing us to reconsider our modeling approach."

Wang's ion-specific recrystallization research stems from his group's cell cryopreservation project. A key reason for cell death during cryopreservation is because large ice crystals grow at the expense of small ones during recrystallization.

During an experiment, one of Wang's students uncovered a striking effect by chance. Adding sodium chloride or phosphate buffer saline produced a profound but previously unexplored effect on the size of recrystallized ice.

In further experiments, Wang's team rapidly froze pure water and three saline solutions, then allowed them to cool at higher temperatures. They found that ions of sodium fluorine produced the smallest ice crystals. Sodium bromine produced larger crystals. Those with sodium iodine produced the largest crystals, which outsized even those produced from pure water.

The Nebraska team conducted molecular dynamics simulations at the Holland Computing Center and the Nebraska Cluster for Computational Chemistry to better understand how fluorine, iodine and bromine ions affect ice recrystallization.

"What we find is that fluorine doesn't get trapped inside the ice, whereas iodine allows that to happen, and to some extent bromine also allows that to happen," Zeng said. "You can use ions to control the ice."

The researchers found that they could tune ice-grain size from approximately 27 microns – roughly half the size of a human hair – to 277 microns.

Explore further: Discovery creates a new paradigm for creating materials from crystals

More information: Shuwang Wu et al. Ion-specific ice recrystallization provides a facile approach for the fabrication of porous materials, Nature Communications (2017). DOI: 10.1038/ncomms15154

Related Stories

Study finds support for new forms of liquid water

April 4, 2017

Putting water in a (really) tight spot and cranking up the pressure could reveal new sides of its already mercurial personality, says a new international study co-authored by chemists at the University of Nebraska-Lincoln.

High storage batteries from sodium ion batteries

October 26, 2016

The mechanism of sodium ion storage in an important two-dimensional material could be a simpler and less toxic route to cheaper batteries, a team of KAUST researchers discovered.

Recommended for you

Artificial photosynthesis gets big boost from new catalyst

November 20, 2017

A new catalyst created by U of T Engineering researchers brings them one step closer to artificial photosynthesis—a system that, just like plants, would use renewable energy to convert carbon dioxide (CO2) into stored chemical ...

Scientific advances can make it easier to recycle plastics

November 17, 2017

Most of the 150 million tons of plastics produced around the world every year end up in landfills, the oceans and elsewhere. Less than 9 percent of plastics are recycled in the United States, rising to about 30 percent in ...

The spliceosome—now available in high definition

November 17, 2017

UCLA researchers have solved the high-resolution structure of a massive cellular machine, the spliceosome, filling the last major gap in our understanding of the RNA splicing process that was previously unclear.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.