Low-temperature fabrication of morphology-controllable Cu2O for electrochemical CO2 reduction

Abstract Cu 2 O has been successfully synthesized in different morphologies/sizes (nanoparticles and octahedrons) via a low-temperature chemical reduction method. Trapping metal ions in an ice cube and letting them slowly melt in a reducing agent solution is the simplest way to control the nanostructure. Enhancement of charge transfer and transportation of ions by Cu 2 O nanoparticles was shown by cyclic voltammetry and electrochemical impedance spectroscopy measurements. In addition, nanoparticles exhibited higher current densities, the lowest onset potential, and the Tafel slope than others. The Cu 2 O electrocatalyst (nanoparticles) demonstrated the Faraday efficiencies (FEs) of CO, CH 4 , and C 2 H 6 up to 11.90, 76.61, and 1.87%, respectively, at −0.30 V versus reference hydrogen electrode, which was relatively higher FEs than other morphologies/sizes. It is mainly attributed to nano-sized, more active sites and oxygen vacancy. In addition, it demonstrated stability over 11 h without any decay of current density. The mechanism related to morphology tuning and electrochemical CO 2 reduction reaction was explained. This work provides a possible way to fabricate the different morphologies/sizes of Cu 2 O at low-temperature chemical reduction methods for obtaining the CO, CH 4, and C 2 H 6 products from CO 2