Optimized CO2 photoreduction using cuprous oxide (Cu2O) nanoparticles synthesized using Psidium guajava extract

Abstract

This work aims to propose earth-abundant materials for CO<inf>2</inf> photoreduction to generate renewable solar fuels to provide practical solutions to global warming. The selected material in this case is cuprous oxide (Cu<inf>2</inf>O), one of the most promising photocatalysts for CO<inf>2</inf> photoreduction due to its high affinity to solar radiation and electronic properties. Cu<inf>2</inf>O nanoparticles (NPs) were synthesized using Psidium guajava residue for the photocatalytic CO<inf>2</inf> reduction. The aqueous residue of the Psidium guajava fruit proved to be suitable for stabilizing and acting as a reducing agent for the synthesis of Cu<inf>2</inf>O NPs. The XRD analysis confirmed the formation of the cubic structure of Cu<inf>2</inf>O. The nanoparticles absorb light from 430 nm with a direct bandgap value of around 1.8 eV. Cu<inf>2</inf>O NPs exhibited activity for CO<inf>2</inf> photoreduction, whose efficiency was optimized by an orthogonal Taguchi L<inf>9</inf> design. The factors studied were catalyst loading, air flow, and temperature. During the use of Cu<inf>2</inf>O NPs in the CO<inf>2</inf> photoreduction HCOOH was identified as the main product, with an optimized production of 103.4 µmol h− 1 under visible light. Also, it was demonstrated the photocatalytic activity of the Cu<inf>2</inf>O NPs for H<inf>2</inf> evolution by water splitting.; Cu<inf>2</inf>O NPs were synthesized using aqueous extract of Psidium guajava. Cu<inf>2</inf>O NPs were used as photocatalyst for CO<inf>2</inf> photoreduction. The products obtained from the photoreduction process were formic acid, methanol and formaldehyde.