In this study, we have considered a Cu nanocube (Cu-NC) based catalyst exposed with (100) facets for CO2 hydrogenation reactions. All the feasible mechanistic pathways for the formations of C1 (HCOOH, CH3OH and CH4) and C2 (C2H4 and C2H5OH) based products have been explored using the density functional theoretical calculations and the most plausible pathways have been identified. The calculated results are compared with the previous reports on the periodic Cu(100) and Cu(111) surfaces, and also on the surface of Cu85 nanocluster and Cu(111) monolayer. The in-depth mechanistic investigation shows that Cu-NC can be very selective towards the C2 based products with a lower limiting potential (calculated) compared to the periodic surfaces. The underlying reasons for such findings have been explained and compared that with the periodic surfaces. We therefore, propose that the Cu-NC based catalysts can be more promising for C2 based products.