Role of SiO2 in TiO2/SiO2 photocatalyst for hydrogen peroxide gas generation from air humidity via photocatalysis

Abstract

This work aims to study the production of hydrogen peroxide gas (H₂O₂) through photocatalysis. It consists of two main parts. In the first part, we explore the optimal conditions for synthesizing H₂O₂ gas from humidity using a gas system photoreactor. Through experimentation, we discovered that the fabricated photoreactor, equipped with three series of coated photocatalyst-supporting plates, can synthesize H₂O₂ gas up to 3 ppmv. The photoreactor incorporates key components, including a photocatalyst material, UV light source, ventilation fan, and air filter. The identified optimal conditions included a relative humidity of 60‒65% RH and an air flow rate of 12.0 m/s. The TiO₂/1%SiO₂ photocatalyst, composed of SiO₂ particles smaller than 63 μm, yielded the most favorable results. The second part focused on studying the role of SiO₂ in TiO₂/SiO₂. We observed that modifying the TiO₂ morphology with SiO₂ created a pore structure on the surface. This structural modification leads to the formation of Ti‒O‒Si bonds, which facilitate electron and hole trapping on the photocatalyst surface. Furthermore, the presence of hydroxyl groups on the surface enhanced the attraction of reactant molecules. XRD results reveal a mixed-phase structure of TiO₂ (anatase‒rutile)/SiO₂ amorphous, contributing to improved electron and hole pathways within the photocatalyst.

Graphical abstract