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

Abstract

This work aims to propose earth-abundant materials for CO 2 photoreduction to generate renewable solar fuels to provide practical solutions to global warming. The selected material in this case is cuprous oxide (Cu 2 O), one of the most promising photocatalysts for CO 2 photoreduction due to its high affinity to solar radiation and electronic properties. Cu 2 O nanoparticles (NPs) were synthesized using Psidium guajava residue for the photocatalytic CO 2 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 2 O NPs. The XRD analysis confirmed the formation of the cubic structure of Cu 2 O. The nanoparticles absorb light from 430 nm with a direct bandgap value of around 1.8 eV. Cu 2 O NPs exhibited activity for CO 2 photoreduction, whose efficiency was optimized by an orthogonal Taguchi L 9 design. The factors studied were catalyst loading, air flow, and temperature. During the use of Cu 2 O NPs in the CO 2 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 2 O NPs for H 2 evolution by water splitting. Graphical Abstract

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