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.

使用以CO ₂为碳源的剩余可再生能源生产甲烷燃料可以实现化石燃料原料的脱碳和替代。_{然而，CO 2}的有效活化通常需要高温。在这里，我们提出了一种使用温和的绿色水热合成法合成的固体催化剂，该方法涉及将间隙碳掺杂到氧化钌中，从而使 Ru 阳离子稳定在低氧化态并形成碳酸氧钌相。_{该催化剂显示出对CO 2}转化的活性和选择性比传统催化剂在更低的温度下转化为甲烷，具有出色的长期稳定性。此外，这种催化剂能够在间歇供电条件下运行，这与基于可再生能源的电力生产系统结合得很好。通过在宏观和原子尺度上结合先进的成像和光谱工具，催化剂的结构和钌物种的性质得到了敏锐的表征，突出显示了低氧化态的 Ru 位点（Ru n + , 0 ^{< n} <  4  ）作为负责高催化活性。这种催化剂提出了使用填隙掺杂剂进行材料设计的替代观点。