Small, two dimensional, Au and Cu nanoparticles in close contact with TiC(001) undergo a charge polarization which makes them very active for H2 dissociation and CO2 activation. Theoretical studies suggest that these systems are suitable candidates for the catalytic synthesis of methanol; which is confirmed by experiments under controlled conditions. These experiments show that the major product over these model catalysts is CO which is produced by the reverse water-gas shift reaction (RWGS, CO2 + H2 ? CO + H2O) whereas the secondary product is methanol (CO2 + 3H2 ? CH)OH + H2O). These experimental finding are rationalized by means of density functional theory (DFT) based calculations on large supercells. The DFT calculations show that for both Au/TiC and Cu/TiC, the combination of the small size of the particle and of the polarization induced by the underlying carbide facilitates the dissociation of the hydrogen molecule with respect to the case of the extended surfaces. Moreover, DFT calculations show that these systems strongly activate CO2 and point to HOCO as a key intermediate for the generation of CO through the RWGS, with the production of methanol probably involving the hydrogenation of a HCOO intermediate or the CO generated by the RWGS. The interesting and appealing features described here for Cu and Au deposition on TiC may not be unique since it has been proven that  other metal carbides (ZrC, VC, MoC, TaC) are also able to induce charge polarization in admetals.

Theoretical studies of Au/TiC and Cu/TiC based catalysts for CO<sub>2</sub> activation and hydrogenation

247th National Meeting (2014)

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Theoretical studies of Au/TiC and Cu/TiC based catalysts for CO2 activation and hydrogenation

Theoretical studies of Au/TiC and Cu/TiC based catalysts for CO₂ activation and hydrogenation