Continuous Hydrothermal Flow Synthesis and Characterization of ZrO2 Nanoparticles Doped with CeO2 in Supercritical Water.

Qingyun Li,Zihua Wang,Xuezhong Wang,Lingyu Liu

doi:10.3390/nano12040668

Abstract

A confined jet mixing reactor operated in continuous hydrothermal flow synthesis was investigated for the synthesis of CeO2-ZrO2 (CZ) nanoparticles. The obtained ultrafine powders were characterized using scanning electron microscopy–energy dispersive spectrometry (SEM-EDS), inductively coupled plasma–atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED), a BET (Brunauer-Emmett-Teller)-specific surface area test and pore analysis, oxygen storage capacity (OSC) test, and a H2 temperature programmed reduction (H2-TPR) test. The XRD results show that all samples were composed of high-purity cubic CZ nanoparticles. High resolution transmission electron microscope (HR-TEM) analysis showed that CZ nanoparticles with uniform size and shape distributions were obtained in this investigation. The d-spacing values, determined based on the TEM-selected area electron diffraction (SAED) patterns, were in good agreements with the reference data. BET results showed that the prepared CZ samples had large specific surface areas. Pore volume and size distribution were obtained by pore analysis. Oxygen pulse adsorption technology was used to test the oxygen storage capacity of the sample. The redox capacity of the CZ material was determined by a H2 temperature-programmed reduction test.

Highlights

CeO2 -ZrO2 (CZ) with a cubic structure has been extensively investigated for catalysis [1], oxygen storage/release capacity (OSC) [2], gas sensors [3,4,5], solid oxide fuel cells (SOFCs) [6,7], and thermal insulation [8] due to its excellent physical and chemical properties, such as high surface area [9,10], good thermal stability [2,6,11], and excellent electrochemical performance [12,13]
CZ samples were prepared with high purity
The Fourier transform infrared spectroscopy (FTIR) spectra, Raman spectra and X-ray diffraction analysis (XRD) results indicate that the obtained CeO2 ZrO2 samples were mixtures of tetragonal and cubic phases

Summary

Introduction

CeO2 -ZrO2 (CZ) with a cubic structure has been extensively investigated for catalysis [1], oxygen storage/release capacity (OSC) [2], gas sensors [3,4,5], solid oxide fuel cells (SOFCs) [6,7], and thermal insulation [8] due to its excellent physical and chemical properties, such as high surface area [9,10], good thermal stability [2,6,11], and excellent electrochemical performance [12,13]. The traditional methods developed for producing CZ, such as hydrolysis [14], precipitation [15], citrate complex [16], etc., are all time consuming and involve complex post-processing, organic solvent use and high energy consumption. Continuous hydrothermal flow synthesis (CHFS) technology, as a simple, efficient and environmentally friendly nanomaterial synthesis process, has attracted considerable attention in recent years [17,18,19,20]

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Conclusion