Preparation of Ag-Loaded Ga₂O₃ Particles by the Ultrasonic Reduction Method and their Photocatalytic Activities for CO₂ Reduction

Abstract

Photocatalytic reduction of CO₂ is attracting attention as one of the CCUS (Carbon dioxide Capture, Utilization and Storage) technologies which are necessary for preventing global warming. Silver (Ag)-loaded Ga₂O₃ photocatalyst is a promising material used for the reduction of CO₂ to CO. In this research, the ultrasonic reduction method was investigated as a method of loading Ag nanoparticles on Ga₂O₃. With this method, Ag nanoparticles were synthesized only by ultrasonic irradiation of silver oxide (Ag₂O) in ethanol solvent. Silver nanoparticles with the particle sizes of 20 ± 2 nm were homogeneously loaded on Ga₂O₃ particles when the loading amount of Ag was in the range of 0.4 wt% to 3.8 wt%. The particle sizes of the loaded Ag particles were ca. 250 nm when using the conventional impregnation and photoreduction methods. Regarding photocatalytic activities for CO₂ reduction, the selectivity toward CO evolution of Ag-loaded Ga₂O₃ prepared by the ultrasonic reduction method was higher than that by the conventional methods. It was shown that Ag loading by the ultrasonic reduction method was not only advantageous for industrial production, but also superior in the photocatalytic performance.