Photoelectrocatalytic performance of nanostructured p-n junction NtTiO₂/NsCuO electrode in the selective conversion of CO₂ to methanol at low bias potentials

Author(s)

de Brito, Juliana Ferreira ; Hudari, Felipe Fantinato ; Boldrin Zanoni, Maria Valnice

• Document type: Journal article
• Source: JOURNAL OF CO2 UTILIZATION; v. 24, p. 8-pg., 2018-03-01.

Abstract

Aiming a selective reduction of CO2 to methanol, a p-n junction semiconductor was constructed based on CuO nanospheres (NsCuO) deposited at TiO2 nanotubes (NtTiO(2)). The NtTiO(2)/NsCuO material demonstrated smaller charge transfer resistance, smaller flat band potential and wider optical absorption when compared with NtTiO(2) and/or Ti/TiO2 nanoparticles coated by higher size particles of CuO (Ti/TiO2/CuO). The selective reduction of dissolved CO2 to methanol was promoted at lower potential of +0.2 V and UV-vis irradiation in 0.1 mol L-1 K2SO4 electrolyte pH 8 with 57% of faradaic efficiency. Even though the performance of the nanostructured material NtTiO(2)/NsCuO was similar to the non-completely nanostructured material Ti/TiO2/CuO (0.1 mmol methanol), the conversion to methanol has been significantly increased when hydroxyls (0.62 mmol L-1) and holes scavengers (0.71 mmol L-1), such as p-nitrosodimethylaniline (RNO) or glucose, respectively, were added in the supporting electrolyte. It indicates that photogenerated electron/hole pairs are spatially separated on p-n junction electrodes, which produces effective electrons and long-life holes, influencing the products formed in the reaction. A schematic representation of the heterojunction effect on the photoelectrocatalytic CO2 reduction is proposed under the semiconductor and each supporting electrolyte, which improves the knowledge about the subject. (AU)

• FAPESP's process: 08/10449-7 - Assessment of occurrence, toxicity/genotoxicity and degradation processes of dyes in effluents and surface water
• Grantee: Maria Valnice Boldrin
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/25343-8 - Simultaneous Oxidation of Organic Compounds in Wastewater Petroleum and Reduction of Dissolved CO2 by Photoelectrocatalysis
• Grantee: Juliana Ferreira de Brito
• Support Opportunities: Scholarships in Brazil - Doctorate