Tunning the Activity of Transition Metal Carbides by Surface Metal Alloying: CO2 Capture as a Case Study

2018 edition

Mart├ş L├│pez Berbel

CO2 is one of the main actors in the greenhouse effect and its removal from the atmosphere is becoming an urgent need. A possible way to decrease the concentration of atmospheric CO2 is by adsorption on an appropriate material. Recently, It has been theoretically predicted that transition metal carbides (TMC) are able to capture, store, and activate CO2 [1]. To further improve the capacity of adsorption of these materials atomic knowledge of the CO2 adsorption is essential. In the present work, we explore the effect of doping the TiC surface by Cr, Hf, Mo, Nb, Ta, V, W, Zr .To this end TiC doped surfaces are modeled through the repeated slab approach with 2├Ś2 and 3├Ś3┬á supercells and state of the art density functional theory based calculations. For the corresponding surface, CO2 adsorption has been investigated by considering the two main configurations (TopC and MMC, see Fig.(1)) that correspond to the undoped surfaces. Calculations predict increased/decreased adsorption energies depending on whether the dopant contributes with less/more electrons than Ti in TiC. These trends are likely to be present in any combination of bimetallic carbides and show that it is well possible to tune the activity of TMCs towards CO2 adsorption for improved greenhouse abatement.

References:

[1] Christian Kunkel, Francesc Vi├▒es, Francesc Illas, Energy Environ. Sci. 9., 141 (2016)