Development of TiO2/CuxO Electrodes as Dark Cathode for Photoelectrochemical CO2 Reduction Reaction Nurafni Setiawati, Iman Abdullah, Jarnuzi Gunlazuardi*
Department of Chemistry, University of Indonesia
*Jarnuzi[at]ui.ac.id
Abstract
Carbon dioxide reduction reaction (CO2RR) is a promising approach for converting CO2 into valuable gases and liquids while supporting the development of sustainable energy systems. One of the widely explored strategies for CO2RR is the photoelectrochemical (PEC) system, in which the reduction reaction occurs at the dark cathode coupled with photoanode, which can be driven by light energy. In this study, a PEC system was designed using a Reduced-TiO2/BiVO4 photoanode and a TiO2/CuxO cathode, with particular focus on the development of the cathodic material. This research aims to develop TiO2-based electrodes modified with CuxO and to investigate the effect of surface modification on their physicochemical properties and electrochemical performance toward CO2RR. TiO2 was synthesized via anodization method to obtain nanotubes structures, followed by Cu2O deposition onto the TiO2 nanotubes using the electrodeposition technique. Subsequent calcination was performed to convert Cu2O into CuO on the TiO2 surface. Optical property analysis revealed a significant reduction in band gap energy from 3.34 eV for TiO2 to 2.0 eV for TiO2/Cu2O and 1.45 eV for TiO2/CuO, indicating altered electronic properties. The electrochemical activities of TiO2, TiO2/Cu2O, and TiO2/CuO electrodes were evaluated in 0.5 M KHCO3 electrolyte using a three-electrode system. The result is that the TiO2/Cu2O electrode exhibits a more positive potential onset for CO2 reduction compared to the other electrodes, suggesting enhanced catalytic activity. These findings highlight the crucial role of CuxO surface modification in tuning the electronic properties of TiO2-based materials and their potential application in efficient and environmentally friendly CO2 conversion systems. This result also supports the integration of the material into a PEC system based on a Reduced-TiO2/BiVO4 photoanode and a TiO2/CuxO cathode.
