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MXene (Ti₃C₂) Vacancy-Confined Single-Atom Catalyst for Efficient Functionalization of CO₂

Zhao, Di, Chen, Zheng, Yang, Wenjuan, Liu, Shoujie, Zhang, Xun, Yu, Yi, Cheong, Weng-Chon, Zheng, Lirong, Ren, Fuqiang, Ying, Guobing, Cao, Xing, Wang, Dingsheng, Peng, Qing, Wang, Guoxiu, Chen, Chen
Journal of the American Chemical Society 2019 v.141 no.9 pp. 4086-4093
activation energy, adsorption, ambient temperature, aniline, carbon dioxide, catalysts, catalytic activity, energy, greenhouse gases, nanoparticles, nanosheets, silane
A central topic in single-atom catalysis is building strong interactions between single atoms and the support for stabilization. Herein we report the preparation of stabilized single-atom catalysts via a simultaneous self-reduction stabilization process at room temperature using ultrathin two-dimensional Ti₃–ₓC₂TyMXene nanosheets characterized by abundant Ti-deficit vacancy defects and a high reducing capability. The single atoms therein form strong metal–carbon bonds with the Ti₃–ₓC₂Ty support and are therefore stabilized onto the sites previously occupied by Ti. Pt-based single-atom catalyst (SAC) Pt₁/Ti₃–ₓC₂Ty offers a green route to utilizing greenhouse gas CO₂, via the formylation of amines, as a C₁ source in organic synthesis. DFT calculations reveal that, compared to Pt nanoparticles, the single Pt atoms on Ti₃–ₓC₂Ty support feature partial positive charges and atomic dispersion, which helps to significantly decrease the adsorption energy and activation energy of silane, CO₂, and aniline, thereby boosting catalytic performance. We believe that these results would open up new opportunities for the fabrication of SACs and the applications of MXenes in organic synthesis.