Rising levels of CO₂ emissions and the search for cleaner energy sources have led to the development of new catalytic systems that can convert CO₂ into useful products. One such chemical is methanol, a liquid fuel with a high energy density that plays an important role in the sustainable carbon cycle.

This work presents a theoretical study of subnanometer metal clusters (of up to five atoms) confined within MOF cavities as catalyst models for CO₂ hydrogenation. The investigation includes not only methanol formation but also the potential formation of other C1 products, such as carbon monoxide and formic acid.

For this purpose, cluster@MOF systems are first designed, and their most stable geometries are identified to serve as starting points for reaction modeling. The DFT molecular dynamics (DFT-MD) method is used to study both the binding of the clusters within the MOF and the CO₂ adsorption. This is followed by investigation of all of the reaction steps, their characterization, and the construction of an energy profile. Transition state validation is performed using the intrinsic reaction coordinate (IRC) method. Detailed study of the structure–function relationships in the proposed catalytic systems will enable an understanding of the reaction mechanisms and optimization of the active site within the cluster@MOF system.