Carbon dioxide is a greenhouse gas and a major cause of global warming. Capturing CO₂ from flue gas after fossil fuel combustion is one approach to prevent its atmospheric concentration from rising. However, solid CO₂ sorbents for such applications need to perform well at a wide range of temperatures, which makes their design challenging.

Jian Ru Gong, Chinese Academy of Sciences (CAS) Center for Excellence in Nanoscience and University of the Chinese Academy of Sciences, Beijing, Mahendra Sunkara, University of Louisville, KY, USA, and colleagues have synthesized lithium hexaoxotungstate (Li₆WO₆) nanowires as CO₂ sorbents. The team used a solid-state reaction between lithium hydroxide and tungsten oxide to prepare the nanowires. They coated a quartz slide with the reaction mixture and subjected the sample to thermal oxidation at 700 °C for 3 h.

The resulting nanowires adsorb CO₂ fast and efficiently at both low and high temperatures. At under dry conditions at 710 °C, the nanowires capture CO₂  with a capacity of 12 % of their own weight in only 60 s. At 30−40 °C and in the presence of water vapor, the nanowires take up 7.6 % of their own weight in CO₂ in the same time. According to the researchers, the synthesized material can chemisorb CO₂ in the absence of water at high temperatures, but water vapor is needed to trap CO₂ at lower temperatures. This can be attributed to a hydroxylation of the nanowire surface, which makes the CO₂ capture thermodynamically more favorable. The nanowire material can be recycled by CO₂ desorption and reused.

• Low-Temperature and Fast Kinetics for CO₂ Sorption Using Li₆WO₆ Nanowires,
  Muhammad Zain Akram, Veerendra Atla, Apolo Nambo, Babajide Patrick Ajayi, Jacek B. Jasinski, Juan He, Jian Ru Gong, Mahendra Sunkara,
  Nano Lett. 2018.
  https://doi.org/10.1021/acs.nanolett.8b01529