Dry Reforming of Methane to Syngas Mediated by Rhodium–Cobalt Oxide Cluster Anions Rh₂CoO^–

Dry reforming of methane (DRM) to syngas is an important route to co-convert CH₄ and CO₂. However, the highly endothermic nature of DRM induces the thermocatalysis to commonly operate at high temperatures that inevitably causes coke deposition through pyrolysis of methane. Herein, benefiting from the mass spectrometric experiments complemented with quantum chemical calculations, we have discovered that the bimetallic oxide cluster Rh₂CoO^- can mediate the co-conversion of CH₄ and CO₂ at room temperature giving rise to two free H₂ molecules and two adsorbed CO molecules (CO_ads). The only elementary step requiring the input of external energy (e.g., high temperature) is desorption of CO_ads from the reaction intermediate Rh₂CoOC₂O₂^-. The doping effect of Co has also been clarified that the Co could tune the charge distribution and orbital energy of the active metal Rh, enabling the enhancement of cluster reactivity toward C-H activation, which is essential to facilitating the DRM to syngas. This work not only underlines the importance of temperature control over elementary steps in practical thermocatalysis but also identifies a promising active species containing the late 3d transition metal to drive DRM to syngas. The findings could provide novel insights into design of bimetallic catalysts for co-conversion of CH₄ and CO₂ at low temperatures.