Carbon mitigation may be about to get a killer app courtesy of nanoparticles

In findings published this July in Nature Communications, researchers from McGill University say they may have found a climate-economic win-win via a helpful photocatalyst. This technique could transform two greenhouse gasses, carbon dioxide and methane, into plastics and fuel suitable for vehicles.

Lead author Professor Chao-Jun Li said, “By tapping into the abundant energy of the sun, we can essentially recycle two greenhouse gases into useful products. The process works at room temperature and doesn’t require the high heat or harsh chemicals used in other chemical reactions.” Li is a Canada Research Chair in Green/Organic Chemistry.

The research team built on previous experiments in which GaN facilitated light-fueled conversions of CH4 to other molecules. Earlier teams have experimented with lead, copper, platinum, and other agents. Li’s team used about a dozen different treatments, including ZnO, TiO₂, and gold-palladium compounds in various ratios combined with the GaN-cr catalyst, identifying AuPd as the most effective.

Nanoparticles made of gold and palladium operate on a GaN framework. This facilitates the oxidation (loss of electrons) of methane (CH₄) and reduction (gain of electrons) of carbon dioxide (CO₂), producing methanol (CH₃OH). Unlike previous methods, this nanoparticle-based technique does not require separate oxidants or reductants, which can produce undesired side products.

The system converts carbon dioxide into carbon monoxide—dangerous but useful—and methane into methanol. Both products are poisonous to humans if inhaled or ingested, respectively, but they are here meant for external use only, such as in in fuel cells and combustion engines.

As with most scientific discoveries, there are many more steps that must be taken before the system sees practical use. Would methane and carbon dioxide be removed from the atmosphere and fed into a scaled-up apparatus or would cars and factories install systems to collect the gases for later transport to a photoconversion facility?

It might be interesting to see an economic analysis of its feasibility.

Su, H., Han, JT., Miao, B. et al. Photosynthesis of CH₃OH via oxygen-atom-grafting from CO₂ to CH₄ enabled by AuPd/GaN. Nat Commun 15, 6435 (2024). https://doi.org/10.1038/s41467-024-50801-3