Selective Reduction of CO 2 on Ti 2 C(OH) 2 MXene through Spontaneous Crossing of Transition States.

Direct reduction of gas-phase CO 2 to renewable fuels and chemical feedstock without any external energy source or rare-metal catalyst is one of the foremost challenges. Here, using density functional theory and ab initio molecular dynamics (AIMD) simulations, we predict Ti 2 C(OH) 2 MXene as an efficient electron-coupled proton donor exhibiting simultaneously high reactivity and selectivity for CO 2 reduction reaction (CRR) by yielding valuable chemicals, formate, and formic acid. This is caused by CO 2 spontaneously crossing the activation barrier involved in the formation of multiple intermediates. Metallic Ti 2 C(OH) 2 contains easily donatable protons on the surface and high-energy electrons near the Fermi level that leads to its high reactivity. High selectivity arises from low activation barrier for CRR as predicted by proposed mechanistic interpretations. Furthermore, H vacancies generated during the product formation can be replenished by exposure to moisture, ensuring the uninterrupted formation of the products. Our study provides a single-step solution for CRR to valuable chemicals without necessitating the expensive electrochemical or low-efficiency photochemical cells and hence is of immense interest for recycling the carbon.