UA researchers improve method to create artificial photosynthesis devices

Researchers at the University of Arkansas have developed a patent-pending method that could lead to reliable, economical and sustainable way to create and store energy from sunlight, according to a news release.

A team of chemistry and chemical engineering researchers have a cost-effective method to create materials for artificial photosynthesis. A device known as an artificial leaf can mimic the process of photosynthesis, a process plants use to convert sunlight into chemical energy, the release shows. An artificial leaf stores energy from sunlight as chemical bonds that can be used to generate power at any time. This matches an advantage that coal and natural gas have over photovoltaics, or solar cells that convert sunlight into solar energy.

Materials for artificial photosynthesis devices are expensive to produce because they integrate all the components to handle light absorption, chemical catalysis and other processes, and these components must be assembled on the nanoscale, which is measured in nanometers or microns. A human strand of DNA is 2.5 nanometers, a human red blood cell is about 5 microns across, and there are 1,000 nanometers in one micron.

“Typical nanostructured materials for these applications use the same expensive and energy-consuming fabrication methods that are used to build microprocessors,” said Robert Coridan, assistant professor of chemistry and biochemistry. Coridan worked with Mya Norman, an instructor in chemistry and biochemistry; Walker Perez, who graduated with a bachelor’s degree in chemical engineering; and Chandler Kline, an undergraduate chemical engineering student.

The method the research team used is called atomic layer deposition and builds nanostructures one atomic layer at a time. They deposited layers of zinc oxide onto a mixture of glass and polymer nanospheres. When the structure is completed, the researchers could dissolve the polymer and leave a network of zinc oxide-coated glass spheres and hollow pores. This contains all the elements needed to act as a photonode, which is the part of an artificial leaf that uses light to convert water into oxygen and energy.

Coridan said a similar process could be used to create a photocathode, which is the part of an artificial leaf that recombines the protons and electrons created by the photonode and forms them into hydrogen, which can be stored and used as fuel. The researchers tested their patent-pending material by using a device called a potentiostat to measure the amount of energy it produced in the form of current. They published the results in journal Advanced Functional Materials.