Low-oxidation-state Ru sites stabilized in carbon-doped RuO2 with low-temperature CO2 activation to yield methane

• Published in: Nature materials Vol. 22; no. 6; pp. 762 - 768
• Main Authors: Tébar-Soler, Carmen, Martin-Diaconescu, Vlad, Simonelli, Laura, Missyul, Alexander, Perez-Dieste, Virginia, Villar-García, Ignacio J, Brubach, Jean-Blaise, Roy, Pascale, Haro, Miguel Lopez, Calvino, Jose Juan, Concepción, Patricia, Corma, Avelino
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.06.2023
• Subjects: Carbon; Carbon dioxide; Carbon sources; Catalysts; Catalytic activity; Cations; Chemical synthesis; Decarbonization; Electric power generation; Fossil fuels; High temperature; Low temperature; Methane; Methane fuels; Oxidation; Renewable energy; Ruthenium; Ruthenium compounds; Ruthenium oxide; Valence
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-023-01540-1

The generation of methane fuel using surplus renewable energy with CO2 as the carbon source enables both the decarbonization and substitution of fossil fuel feedstocks. However, high temperatures are usually required for the efficient activation of CO2. Here we present a solid catalyst synthesized using a mild, green hydrothermal synthesis that involves interstitial carbon doped into ruthenium oxide, which enables the stabilization of Ru cations in a low oxidation state and a ruthenium oxycarbonate phase to form. The catalyst shows an activity and selectivity for the conversion of CO2 into methane at lower temperatures than those of conventional catalysts, with an excellent long-term stability. Furthermore, this catalyst is able to operate under intermittent power supply conditions, which couples very well with electricity production systems based on renewable energies. The structure of the catalyst and the nature of the ruthenium species were acutely characterized by combining advanced imaging and spectroscopic tools at the macro and atomic scales, which highlighted the low-oxidation-state Ru sites (Run+, 0 < n < 4) as responsible for the high catalytic activity. This catalyst suggests alternative perspectives for materials design using interstitial dopants.Activating CO2 to form methane is a potential strategy for energy decarbonization, but to activate CO2 typically requires high temperatures. Here a ruthenium oxycarbonate is presented that forms by carbon interstitial doping of RuO2, and this catalyst enables CO2 activation at 50 °C.