In contrast, hydrophobicity is advantageous for catalysts applied in gas diffusion electrodes, which feed CO2 to the catalyst directly from the gas phase and the reaction largely occurs at a gas-liquid-solid interphase. In this context, rationally incorporated hydrophobic elements have greatly boosted the performance of heterogeneous catalysts in GDE-based reactors. However, these efforts to date have only been limited to heterogeneous catalysts. Molecular CO2R catalysts have indeed been integrated with gas-fed flow cells and initial results have demonstrated that phthalocyanines/porphyrins, Co quaterpyridine and Ni cyclam 19 catalysts can also function in this geometry. However, most of these molecular systems have been metal complexes that possess an extended π-conjugated system that facilitates their ease of adsorption onto the carbon surfaces in a GDE. This presents a design constraint, though this can also be circumvented by using hydrophobic self-assembly to immobilize the catalysts on the GDE surface as an alternative route.