Activation of Pt nanoclusters on TiO2 via tuning the metallic sites to promote low-temperature CO oxidation

Abstract

Metallic Pt sites are imperative in the CO oxidation reaction. Herein, we demonstrate the tuning of Pt sites by treating a Pt catalyst in various reductive atmospheres, influencing the catalyst activities in low-temperature CO oxidation. The H2 pretreatment of Pt clusters at 200◦ C decreases the T50 from 208◦ C to 183◦ C in the 0.1 wt % Pt/TiO2 catalyst. The T50 shows a remarkable improvement using a CO pretreatment, which decreases the T50 further to 135◦ C. A comprehensive characterization study reveals the integrated reasons behind this phenomenon: (i) the extent of PtO transition to metallic Pt sites, (ii) the ample surface active oxygen triggered by metallic Pt, (iii) the CO selectively adsorbs on metallic Pt sites which participate in low-temperature CO oxidation, and (iv) the formation of the unstable intermediate such as bicarbonate, contributes together to the enhanced activity of CO pretreated Pt/TiO2.