Carbon dioxide is a greenhouse gas. Capturing and using it as a chemical feedstock would, thus, be environmentally friendly. One reaction that can be used for this is CO₂ hydrogenation, which gives methane and water. The methane obtained from this reaction can, e.g., be used to store renewable energy. However, existing catalysts for this reaction require high temperatures (300–500 °C).

Patricia Concepción, Avelino Corma, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas (UPV-CSIC), Valencia, Spain, and colleagues have developed core-shell nanoparticles that can catalyze CO₂ hydrogenation at comparatively low temperatures of 160–200 °C. The nanoparticles have a metallic ruthenium core and a ruthenium carbide shell and were prepared via a hydrothermal synthesis.

The catalyst activates both CO₂ and H₂. It provides 100 % selectivity for methane and does not produce carbon monoxide. The team attributes the high activity to active sites associated with the surface ruthenium-carbide species on the nanoparticles. These are not present in previously reported ruthenium catalysts for this reaction.

• Hydrothermal Synthesis of Ruthenium Nanoparticles with a Metallic Core and a Ruthenium Carbide Shell for Low-Temperature Activation of CO₂ to Methane,
  Jorge Cored, Andrea García-Ortiz, Sara Iborra, María J. Climent, Lichen Liu, Cheng-Hao Chuang, Ting-Shan Chan, Carlos Escudero, Patricia Concepción, Avelino Corma,
  J. Am. Chem. Soc. 2019.
  https://doi.org/10.1021/jacs.9b07088