Angew | Super Xin In Situ System Helps Zhejiang University's Wang Yong Research Group Reveal the Oscillatory Behavior of Metal Carrier Strong Interaction in Pd/TiO ₂ under Redox Conditions

First author: Chen Yuhui

Corresponding authors: Jiang Ying, Wang Yong

Communication unit: Electron Microscopy Center of Zhejiang University&School of Materials Science and Engineering of Zhejiang University

Super New ChipTransmission electron microscopy dual tilt heating in-situ system

InIn situ analysis, this paper utilizesUltra New Core Transmission Double Tilt Heating In Situ System and CHIPNOVA In Situ Heating Chip，Prepare itPd/TiO ₂ catalyst was dispersed on the sample chip and loaded into ETEM for observation using a double tilted heating sample rod.

1、 Full text overview

Wang Yong's research group at Zhejiang University utilizes environmental transmissionElectron Microscopy Technology (ETEM) Discovered Pd Under Specific Redox Conditions/The SMSI coating layer on the surface of TiO ₂ catalyst exhibits oscillatory behavior, which enables the SMSI coating layer to act as a dynamic temporary reservoir of Ti, capturing reduced Ti from the carrier and driving the epitaxial growth of TiO ₂ carrier. This discovery expands our understanding of the dynamic behavior and carrier material transport of SMSI under reaction conditions, and provides a new mechanism for solid-state growth of nanostructures. The above research results were published in Angew!In this groundbreaking experiment, the CHIPNOVA (Ultra New Core) transmission electron microscopy dual tilt heating in-situ system provided key technical support for the research.

2、 Background introduction

Metal nanoparticles, due to their high efficiency, multifunctionality, and controllability,It holds an indispensable position in the field of modern catalytic science. The interaction mechanism between metal nanoparticles and oxide carriers has always been a core research topic, among which metal carrier strong interaction (SMSI) has attracted much attention due to its special interface characteristics. However, the experimental construction and configuration control of SMSI coverage layers are highly dependent on the chemical environment, and the dynamic behavior of SMSI under redox conditions is still unclear. At the same time, there is still a significant lack of understanding of its atomic scale evolution mechanism. In response to the above issues, Wang Yong's research group utilized the latest ETEM andCHIPNOVA in-situ systemWe conducted in-depth research and observed the mass transfer process and carrier dynamic response related to SMSI changes at the atomic scale.CHIPNOVA transmission electron microscopy dual tilt heating in-situ systemTo provide key technical support for the experiment, itThe special dual tilt function and high-precision temperature control (≤ 0.01 ℃ stability) enable atomic scale dynamic observation of materials at precise temperatures.

3、 Research Highlights

1. In situ observation and mechanism revelation: ThroughETEM real-time tracking found that the oscillation originated from the competition of oxidation-reduction conditions, causing the TiO ₓ coating layer to switch between single and double layers, and Pd nanoparticles to rotate under stress.

2. Atomic scale analysis: Accurately identify the double-layer structure features of 3.0 Å/3.4 Å.

4 Graphic and textual explanation

Figure 1: Quasi in situ observation of Pd/TiO ₂ under different atmospheres: SMSI coating was formed in pure O ₂, H ₂, and 5:1 O ₂/H ₂ mixed atmospheres, but under redox conditions, the coating was partially destroyed and carrier protrusions appeared at the interface.

Figure 2: In situ ETEM tracking of structural evolution under mixed atmosphere: SMSI bilayer coating oscillates at the interface, accompanied by the addition of atomic layers on the carrier protrusions, supporting the growth of protrusions towards nanowires.

Figure 3: In situ characterization under pure O ₂ conditions: SMSI coverage layer extends to push Pd particles away from the carrier, and the carrier protrusions grow into nanowires. EELS confirms that the coverage layer contains Ti ³ ⁺.

Figure 4: Observing the oscillation behavior along the TiO ₂ [001] axis: The number of SMSI coating layers is positively correlated with the number of carrier protrusion atoms, and the rotation of Pd particles is related to the interface topology.

5、 Summary and Expectations

1. research findings

*Revealing the SMSI oscillation phenomenon of Pd/TiO ₂ under redox conditions, the cover layer serves as a dynamic storage reservoir for Ti, driving the sharp growth of carrier protrusions.

The oscillation mechanism does not rely on the epitaxial relationship between Pd and TiO ₂, but is dominated by Ti migration regulated by redox equilibrium.

2. scientific significance

This achievement expands our understanding of the dynamic behavior of SMSI under reaction conditions and provides a new perspective for understanding the correlation between catalytic performance and SMSI.

The study proposed an SMSI mediated nanowire growth mechanism, providing new ideas for the synthesis of one-dimensional nanomaterials.

3. Future Direction

Explore the specific effects of SMSI oscillation on the performance of catalytic reactions such as CO ₂ hydrogenation and oxidation reactions.

Study the SMSI dynamic behavior of other metal carrier systems (such as Pt/CeO ₂, Ni/TiO ₂) under redox conditions.