Activity and stability of alloyed NiCo catalyst for the dry reforming of methane: A combined DFT and microkinetic modeling study

Dry reforming of methane (DRM) takes the greenhouse gas methane and carbon dioxide as reactants to produce syngas, showing positive effect on the ecological environment and energy conversion. Although pristine Ni and Co catalysts show high activity during this process, they are easily deactivated. Ni catalysts tend to deposit carbon, while Co catalysts would be oxidized. Compared with Ni, the formation of a one to one ratio NiCo alloy generally shows higher catalyst reactivity. However, there are still contradictions regarding the stability of this alloy catalyst. In this work, we used a combination of density functional theory calculations and microkinetic simulations to understand how the surface structure of the alloy affects the activity and stability of the catalyst. Possible terminations of NiCo alloys were considered and compared regarding the reaction rates, coverage of surface species and rate controlling transition states. Based on these results and those reported in our previous work, understandings on experimental observations can be obtained.