MXene\n(Ti₃C₂) Vacancy-Confined\nSingle-Atom Catalyst for Efficient Functionalization of CO₂

Abstract

A central topic in single-atom catalysis\nis building strong interactions\nbetween single atoms and the support for stabilization. Herein we\nreport the preparation of stabilized single-atom catalysts via a simultaneous\nself-reduction stabilization process at room temperature using ultrathin\ntwo-dimensional Ti_3–<i>x</i>C₂T_<i>y</i>MXene nanosheets characterized by abundant\nTi-deficit vacancy defects and a high reducing capability. The single\natoms therein form strong metal–carbon bonds with the Ti_3–<i>x</i>C₂T_<i>y</i> support and are therefore stabilized onto the sites previously\noccupied by Ti. Pt-based single-atom catalyst (SAC) Pt₁/Ti_3–<i>x</i>C₂T_<i>y</i> offers a green route to utilizing greenhouse gas\nCO₂, via the formylation of amines, as a C₁ source\nin organic synthesis. DFT calculations reveal that, compared to Pt\nnanoparticles, the single Pt atoms on Ti_3–<i>x</i>C₂T_<i>y</i> support feature\npartial positive charges and atomic dispersion, which helps to significantly\ndecrease the adsorption energy and activation energy of silane, CO₂, and aniline, thereby boosting catalytic performance. We\nbelieve that these results would open up new opportunities for the\nfabrication of SACs and the applications of MXenes in organic synthesis.