At high over-potentials, copper electrodes can reduce CO2 to ethylene in moderate yields. More recently, metallic copper nanomaterials have also been shown to effect this transformation, often with lower over-potentials, better stability and higher selectivity than their polycrystalline counterparts. However, several mechanistic questions concerning this transformation remain unanswered, especially in regards to the critical C-C bond forming step. The synthesis of mono-disperse, atomically precise Cu nanomaterials could help to elucidate these questions, but thus far, these materials have remained elusive. In this presentation I will describe our efforts to generate well-defined Cu nanocrystals, and discuss their reactivity with CO2 and other small molecules.