Nature performs catalytic conversion of carbon dioxide for the synthesis of energy vectors and organic compounds by exploiting nano-sized or single-atom photosystem and ezymatic catalytic centers, where metals (Mn, Cu, Ni, Fe ...) are supported by C, S, or N linkers. A thorough insight down to the single-atom level is necessary in order to mimic Nature in model, synthetic systems. In the specific, the behavior of self-assembled 2D arrays of zero-dimensional, supported catalytic centers will be presented. The results of in situ spectroscopy approaches at near-ambient pressure will be discussed, corroborated by microscopy and ab initio theoretical methods. Starting from the example of graphene-supported metal nanoparticles, a comparison with metalorganic frameworks will be driven by discussing the properties of specific systems like graphene- and alumina-supported iron phthalocyanine layers, focusing on structural, electronic, and chemical characters. Controlled tuning of these systems can be accomplished in principle by tailoring the electronic density of states of the support and by alloying of the zero-dimensional metal reactive centers.