Ultra-Fine Pt Entities on High-Index CeO <sub>2</sub> (112) Facet Significantly Boosting Low Temperature Water–Gas Shift Reaction
Qiangqiang Xu, Ze Wang, Jing Shi, Yiming Su, Xinzhen Feng, Weijie Ji, Chak‐Tong Au
Abstract
In this study, two tactics were employed to develop a very efficient and durable Pt-based catalyst for low-temperature water gas shift (WGS) reaction. First, through facet engineering of CeO 2, the dominantly exposed (112)/(110) facets of the oxygen-deficient CeO 2 hexagonal prism (CeO 2 –HP) were established. Second, the Pt single atoms (SAs) and Pt fine clusters (FCs) were anchored to CeO 2 –HP(112)/(110) with the Pt δ+ –O v –Ce 3+ and Pt 2+ –O 2– –Ce 4+ interfacial sites, verified by AC-HAADF-STEM and XAFS measurements. The as-obtained 0.10Pt/CeO 2 –HP achieved a CO conversion rate of 12.63 mmol CO g Pt –1 s –1 and a TOF as high as 2.46 s –1 at 250 °C, 2.6-fold that of benchmark Pt/Fe-0.01 SAC at 300 °C (0.93 s –1 ). The exposed CeO 2 {112} facets constitute abundant oxygen vacancies and an enhanced Pt dispersion. In-situ FTIR study demonstrated the synergetic effect between the Pt δ+ –O v –Ce 3+ and Pt 2+ –O 2– –Ce 4+ interfacial sites which modulates the competitive adsorption of CO and H 2 O. The DFT simulations revealed that the high density of oxygen vacancy over CeO 2 –HP(112) boosts H 2 O dissociation, causing a substantial enhancement in catalytic performance and a variation in the reaction route. This work provides in-depth insights into how the well-controllably assembled interfacial structure functions electronically and is structurally efficient for the target reaction.