How bulk and surface properties of Ti4SiC3, V4SiC3, Nb4SiC3 and Zr4SiC3 tune reactivity: A computational study

We present several in silico insights into the MAX-phase of early transition metal silicon carbides and explore how these affect carbon dioxide hydrogenation. Periodic desity functional methodology is applied to models of Ti4SiC3, V4SiC3, Nb4SiC3 and Zr4SiC3. We find that silcion and carbon terminations are unstable, with sintering occuring in vacuum and significant reconstruction taking place under an oxidising enviroment. In contrast, the metal terminated surfaces are highly stable and very active towards CO2 reduction. However, we prodict that under reaction conditions these surfaces are likely to be oxidised. These results are compared to studies on comparable materials and we predict optimal values for hydrogen evolution and CO2 reduction.