Electrochemical Reduction of CO₂ to C2 Hydrocarbons Using Cu 3D Nanostructures

Although Cu 3D structures are widely used in electrocatalytic practice, this electrode has not been studied enough in relation to the electrochemical transformation of CO₂ to C2 products. Cu foam samples were deposited from acidic solutions with varying concentrations of primary components (H₂SO₄, CuSO₄, and Cl^- ions) with the aim of determining the relationship between catalyst structure and activity/selectivity in producing C2 gaseous compounds during CO₂ electrochemical reduction. The deposited samples were characterized using SEM and electrochemical techniques, including Pb underpotential deposition (UPD), to determine the contribution of crystal facets. The most efficient electrodes were found to be those deposited in a solution without Cl^- additives. Their effectiveness was related to the shape and size of the crystallites forming the branches. These crystallites create a spatial structure that supports C-C coupling and C2 gaseous compound formation. The higher catalytic activity and selectivity of this electrode may also be related to its lower Cu(111) facet input to the overall facet distribution and its higher number of structural defects. Despite the higher electrochemically active surface area of samples deposited in the presence of Cl^- ions, their lower activity is related to structural characteristics that cause possible mass transfer limitations.