Room-Temperature Catalytic and Photocatalytic Oxidation of CO over Pt/TiO2 Catalysts in an LED-Based Flow Reactor: Effects of Pt Loading and Oxidation State

The build-up of carbon monoxide (CO) in confined spaces can pose serious risks to human health. One method of mitigating CO in air is catalytic oxidation. Low-temperature catalytic oxidation of CO is desirable to enhance energy efficiency and sustainability. Noble metal catalysts have been shown to be active catalysts for CO oxidation at low temperatures. In addition, photocatalysis has been demonstrated as a method to degrade harmful gas-phase compounds into less toxic ones at room temperature. In this study, the effects of platinum (Pt) loading and oxidation state on a TiO2 (P25) support were investigated in a light-emitting diode (LED)-based flow reactor for the room-temperature catalytic and photocatalytic oxidation of CO in air. It was found that the catalytic activity increased with Pt loading up to 5 wt%, and catalytic activity was significantly higher when the Pt was reduced (Pt0) on the catalyst compared to oxidized platinum (Pt2+, Pt4+). Visible light absorption increased with increasing platinum loading on TiO2, and the catalyst activity for room-temperature CO oxidation increased with exposure to both ultraviolet (UVA) and visible light. Platinum is responsible for the adsorption of CO and the activation of adsorbed oxygen and CO, and it interacts with the photogenerated electrons upon exposure to light to enhance the photocatalytic activity of Pt/TiO2 catalysts for the room-temperature oxidation of CO.