Single Zn atom catalyst on Ti2CN2 MXenes for efficient CO oxidation.

Carbon monoxide (CO) oxidation is an efficient way to purify CO. Herein, the geometrical properties, electronic structure and CO oxidation catalytic activity of Zn single atom catalyst (SAC) on pristine Ti 2 CT 2 (T = N/O/F) MXenes and defective ones (T v /Ti 2 CT 2) with a functional-group vacancy (T v) were calculated by using density functional theory (DFT) calculations. The results revealed that Ti 2 CN 2 may serve as an excellent substrate to stabilize single Zn atom catalyst, compared to Ti 2 CT 2 (T = O/F) and T v /Ti 2 CN 2 (T = N/O/F). The catalytic oxidation mechanism of CO on the surface of Zn–Ti 2 CN 2 has been systematically studied. The Eley–Rideal (ER) mechanism was identified as the most preferential pathway with the smallest rate-determining energy barrier of 0.06 eV, since the Zn atom can considerably promote the activation of O 2 molecule and weaken the O–O bond. Electronic structure analysis confirmed the synergistic effects of adsorbed single Zn atom and substrate in regulating electron transfer, activating the adsorbed small molecule reactants and enhancing CO oxidation activity. Overall, this work reveals that Zn–Ti 2 CN 2 could be a promising low-temperature CO oxidation candidate and probably provides a new theoretical guidance and inspiration for the experimental and theoretical research to design more effective single atom catalysts with nonprecious metals. [Display omitted] • The pristine Ti 2 CN 2 MXene serves as an excellent support of the transition metal Zn atoms. • The Zn-SACs supported on pristine Ti 2 CN 2 show high catalytic activity for CO oxidation. • The Zn–Ti 2 CN 2 can capture, activate O 2 molecule and weaken the O–O bond. • This study highlights the potential applications of Zn-SACs as catalysts. [ABSTRACT FROM AUTHOR]