Recycling Copper Wire Waste into Active Cu-based Catalysts for Value-Added Chemicals Production via CO2 Electrochemical Reduction

The CO₂ electroreduction reaction (CO₂RR) is a method for producing value-added compounds from CO₂. This study aimed to use copper from wiring waste to create Cu-based catalysts on Vulcan XC-72R carbon for converting CO₂ into valuable chemicals. Copper nanopowder with an average crystallite size of 27 nm derived from the wiring waste solution was utilized as the starting material for mono and bimetallic catalysts preparation. During the bimetallic PdCu/C catalyst synthesis, a galvanic displacement reaction between Pd and Cu occurred, resulting in the formation of PdCu alloy and a reduction in the copper crystallite size. The inclusion of Pd on Cu/C in CO₂RR decreased the onset potentials for C1 and C2 chemical production. The yields of methanol, formic acid, and formaldehyde products were generally increased as the Pd:Cu ratio increased. The 1:2-PdCu/C exhibited the smallest crystallite size and an onset potential of less than -1.0 V, resulting in the highest Faradaic efficiency of the products. This catalyst converted CO₂ into formic acid (FE = 71.5%) at a potential of -0.8 V and methanol (FE = 65.4%) at -0.5 V. The catalyst’s stability was demonstrated for more than 6000 seconds at current densities of approximately 2 mA mg^-1_catalyst.