One of the challenges in curbing the worsening effects of climate change is in reducing our continuous carbon dioxide (CO2) emissions - and a new technology promises a green and sustainable solution in doing so.
The drastic increase in CO2 levels, mostly from anthropogenic activities, has been identified as the main cause of global warming, which in turn causes abnormal weather patterns around the world. It has led a significant body of research to focus on finding ways to reduce our CO2 emissions or to find a way to reduce its levels in the atmosphere. One concept that is being explored nowadays is to break down or "decompose" CO2 in the air through photocatalysts - compounds that absorb light and use the energy to "catalyze" or speed up chemical reactions. These chemical reactions then chemically break down CO2 in the surroundings.
Utilizing Photocatalyst Technology for CO2 Reduction
A new attempt at the promising technology has been made by researchers from the Nagoya Institute of Technology in Japan. They present their strategy in the paper "One-step synthesis of visible light CO2 reduction photocatalyst from carbon nanotubes encapsulating iodine molecules," appearing in the latest Scientific Reports journal.
Led by Shinji Kawasaki and Yosuke Ishii, the latest effort aims to provide an efficient CO2 reduction technology assisted by solar energy. Their work begins with working around the limited usability of silver iodate (AgIO3), a photocatalyst material that has been previously considered for its ability to aid in the CO2 reduction reaction. While it is a promising photocatalyst, its feasibility has been hindered by the need for higher energy levels compared to what visible light can provide. This, in turn, makes it inefficient and impractical for real-world applications. Visible light also composes a large part of solar radiation, making compatibility an important requirement for feasible photocatalyst solutions.
Multiple studies have focused on the efficiency and stability of silver iodate, including a 2014 study published in the Nanoscale journal and a one-pot precipitation preparation of silver iodate and silver bromide and its performance as a photocatalyst in a December 2020 study in the Materials Science in Semiconductor Processing journal.
A New Improvement on Silver Iodate
Previous efforts have tried to work around the efficiency problem by combining silver iodate (AgIO3) with silver iodide (AgI), which is more efficient in absorbing and utilizing visible light. However, the silver composites are only possible using complicated synthesizing processes, which poses a problem with scalability, making large-scale manufacturing a challenge. Additionally, even when combined, silver composites still don't provide efficient transmission of photoexcited electrons - a key parameter to the material being a photocatalyst.
"We have now developed a new photocatalyst that incorporates single-walled carbon nanotubes (SWCNTs) with AgIO3 and AgI to form a three-component composite catalyst," Dr. Kawasaki said in a Nagoya Institute of Technology research news article. The researcher added that the role of these carbon nanotubes includes solving the synthesis and the pathway problems with silver iodate - silver iodide.
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