Unveiling the role of dopant electronegativity in improving the catalytic performance of MXene catalysts in propane dehydrogenation using microkinetic simulations

Abstract

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