By Kathleen Berger, Executive Producer of Science & Technology in coordination with Washington University in St. Louis
Rich clay deposits once made St. Louis the nation’s brick capital. Distinctive red bricks are part of the city’s appealing architecture. Few cities have as many brick buildings as you find in St. Louis.
Assistant chemistry professor Julio D’Arcy, PhD, at Washington University in St. Louis became immersed in red bricks when he moved to St. Louis. In fact, he became inspired! D’Arcy moved into a brick home in Richmond Heights. All the brick in his neighborhood and the brick buildings on his drive to the Washington University campus, as well as the brick buildings on campus, became his inspiration.
“You go into one of these old houses, you find interior areas that have these red brick, and they can potentially be used for storing energy,” said D’Arcy. “It would be completely autonomous, off the grid in theory. This definitely was St. Louis trying to inspire us!”
Imagine plugging in to your brick house. Red bricks — some of the world’s cheapest and most familiar building materials — can be converted into energy storage units that can be charged to hold electricity, like a battery, according to D’Arcy’s research.
D’Arcy’s new application for bricks is part of green chemistry, also called sustainable chemistry.
“We look for inspiration in nature and we try to find materials that are commonly regarded as waste or not useful chemical by-products,” said D’Arcy. “We look at materials like the red pigment in bricks, which is known as rust, or iron corrosion, as a possible source of feed stock for doing chemical synthesis. So the idea of using minerals for materials is the essence of chemistry. And we were successful.”
Brick has been used in walls and buildings for thousands of years, but rarely has been found fit for any other use. Now, D’Arcy and his team of chemists in Arts & Sciences have developed a method to make or modify “smart bricks” that can store energy until required for powering devices. His proof-of-concept was published Aug. 11 in Nature Communications shows a brick directly powering a green LED light.
“Our method works with regular brick or recycled bricks, and we can make our own bricks as well,” said D’Arcy. “As a matter of fact, the work that we have published in Nature Communications stems from bricks that we bought at Home Depot right here in Brentwood (Missouri); each brick was 65 cents.”
D’Arcy and colleagues, including Washington University graduate student Hongmin Wang, first author of the new study, showed how to convert red bricks into a type of energy storage device called a supercapacitor.
“In this work, we have developed a (plastic) coating of the conducting polymer PEDOT, which is comprised of nanofibers that penetrate the inner porous network of a brick; a polymer coating remains trapped in a brick and serves as an ion sponge that stores and conducts electricity,” D’Arcy said.
The red pigment in bricks — iron oxide, or rust — is essential for triggering the polymerisation reaction. The authors’ calculations suggest that walls made of these energy-storing bricks could store a substantial amount of energy.
“We were able to change the red pigment in a brick, which is rust, into this plastic that we make in a lab. We make a very thin film of a plastic. It is nanofibrillar. A nanofibrillar coating on a brick increases the surface area. So when you build a house and you put your red bricks in a house, if they have our coating, which is blue, they have a much larger surface area.”
D’Arcy said the PEDOT (plastic) coated bricks are ideal building blocks that can provide power to emergency lighting for 50 minutes. The wall can be recharged in minutes to maximum capacity to continue to power the light for hours.
“We envision that this could be a reality when you connect our bricks with solar cells — this could take 50 bricks in close proximity to the load. These 50 bricks would enable powering emergency lighting for five hours.”
A brick wall could serve as a supercapacitor that can be recharged hundreds of thousands of times within an hour.
“Let’s say you have a thousand brick. You can power a laptop (computer),” he said.
D’Arcy explained how the supercapacitor is ideal for powering environmental microelectronics sensors.
“The coatings that we have produced, allow us to also make devices on bricks that can sense the temperature in a house, carbon dioxide in the house, gasses in the house.”
D’Arcy said the development is a universal strategy that can work on any kind of brick for retrofitting an old home or building a new home.
“Other oxides of iron that you find in minerals are not just red. They can be yellow, green, black or brown and you can mix them so you can have bricks of different colors.”
The lifetime of this proof-of-concept application is 30 years. D’Arcy said the brick would be recoated 30 years down the road to maintain the brick as a renewable source of energy.