Unveiling the role of dopant electronegativity for improved catalytic performance of MXenes catalysts in propane dehydrogenation by microkinetic simulations

Abstract

MXenes hold the potential to enable more efficient and sustainable catalytic processes, and their unique surface chemistry give them an edge over traditional catalysts for on-purpose optimization. Given this potential, current study delves into the role of dopant to enhance the catalytic properties of V3C2O2 during propane dehydrogenation (PDH). The DFT calculations and microkinetic simulations revealed that a lower dopant electronegativity with d-band center close to the Fermi level increases the charge at active sites, facilitating C-H bond activation. A strong linear relationship is observed between dopant electronegativity and the first C-H bond activation barrier, in which Cr dopant with low electronegativity shows the best performance with 2.5 times lower barrier than the pristine surface. Four different pathways are examined at same footing which reveal the most favorable mechanism initiated by secondary hydrogen abstraction and surface bound n-propyl. Also, the turnover frequency (TOF) of propane conversion for Cr-V3C2O2 nearly five times higher than the pristine V3C2O2 MXene and is comparable to conventional PDH catalysts, validating the effectiveness of doping strategy. The calculated TOF is well regulated by the adsorption energies of propane and n-propyl species, providing a valuable tool for catalyst design. This work uncovers the impact of dopant electronegativity on the catalytic performance, and presents a practical strategy for future catalyst advancements.