Cu2O/TiO2 heterostructures for CO2 reduction through a direct Z-scheme: Protecting Cu2O from photocorrosion

Aguirre, Matías E.; Zhou, Ruixin; Eugene, Alexis J.; Guzman, Marcelo I.; Grela, María A.

doi:10.1016/j.apcatb.2017.05.058

Abstract Cu₂O 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 Cu₂O 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 Cu₂O electrocatalyst (nanoparticles) demonstrated the Faraday efficiencies (FEs) of CO, CH₄, and C₂H₆up 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 CO₂reduction reaction was explained. This work provides a possible way to fabricate the different morphologies/sizes of Cu₂O at low-temperature chemical reduction methods for obtaining the CO, CH_4,and C₂H₆products from CO₂

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