Effect of Ethanol as a Solvent Mixture during SILAR Deposition on the Properties of Cu2O/TiO2 for Photo-electrocatalytic CO2 Reduction
Graciella Stephanie Dwiningtyas (a), Iman Abdullah (a), and Jarnuzi Gunlazuardi (a*)

a) Departement of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia
*jarnuzi[at]ui.ac.id

Abstract

Carbon dioxide (CO2) is a major contributor to greenhouse gases, playing a significant role in global warming and climate change. Various strategies have been developed to reduce atmospheric CO2 levels, one of which is its utilization through conversion into value-added chemicals. Photo-electrocatalysis is a promising approach for CO2 conversion, as it utilizes both solar and electrical energy to drive the CO2 reduction reaction (CO2RR) more efficiently. In the present photo-electrocatalytic CO2RR systems, TiO2 semiconductors are being used as photocathodes due to their high chemical stability, good corrosion resistance, and relatively efficient charge transfer properties. However, TiO2 has a wide band gap (~3.2 eV), making it active in the ultraviolet region and limiting its ability to utilize the solar spectrum effectively. Therefore, modification of TiO2 is necessary to enhance its responsiveness to visible light. One approach involves the deposition of Cu2O onto the TiO2 surface to form a heterojunction material, which can improve visible light absorption and enhance the separation efficiency of electron-hole pairs. Cu2O was deposited onto TiO2 nanotubes using the SILAR (Successive Ionic Layer Adsorption and Reaction) method with water as the solvent. However, the use of water can result in suboptimal deposition due to the relatively hydrophobic nature of the TiO2 surface, which hinders interaction between ionic precursors and the substrate. Therefore, this study investigates the effect of adding an organic solvent, ethanol, at varying concentrations during the Cu2O deposition process on the characteristics and physicochemical properties of Cu2O/TiO2 for CO2RR. TiO2 nanotubes were synthesized via anodization, followed by Cu2O deposition using the SILAR method and subsequent chemical reduction. The materials were characterized using FTIR, UV-DRS, and electrochemical analysis. The results indicate successful Cu2O deposition on TiO2 across all solvent ratios, with electrochemical analysis showing a more positive onset potential for Cu2O/TiO2 compared to bare TiO2.

Keywords: CO2RR, TiO2, Cu2O/TiO2, SILAR

Topic: Inorganics Chemistry