Tuning the Activity of Molybdenum Carbide MXenes for CO<sub>2</sub> Electroreduction by Embedding the Single Transition-Metal Atom
Yue Zhang, Zexing Cao
Abstract
Mo2C electrocatalysts may reduce CO2 to CH4 with the low overpotentials, but also accelerate the hydrogen evolution reaction (HER). Here a series of the transition-metal-embedded Mo2C (M@Mo2C) MXenes are screened by first-principles calculations, and Cr@Mo2C, Mn@Mo2C, Fe@Mo2C, and Co@Mo2C are predicted to have higher activity and selectivity toward CO2ER than HER, compared to the pristine Mo2C. In particular, Fe@Mo2C and Co@Mo2C are quite promising for CO2ER to CH4 or CH3OH at low limiting potentials. In addition, the scaling relationship between the limiting potential and the binding strength of *OH as well as the correlationship among the binding energies of the key intermediates have been investigated, and the binding energy of *OH can serve as the activity descriptor for CO2ER to CH4. Furthermore, Fe@Mo2C may reduce CO2 to C2H4 and CH3CH2OH, which can serve as a potential 2D electrocatalytic material for CO2ER to C1 and C2 products.