Structural Characterization of Ceria-Supported Pt Nanoparticles by Flame-Assisted Spray Pyrolysis Using a Burner Diffusion Flame
Structural Characterization of Ceria-Supported Pt Nanoparticles by Flame-Assisted Spray Pyrolysis Using a Burner Diffusion Flame
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DOI：
10.1021/acs.energyfuels.1c01296
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发表时间：
2021-08
期刊：
影响因子：
5.3
通讯作者：
Tsuyoshi Nagasawa;K. Matsumoto;Naoya Minegishi;H. Kosaka
中科院分区：
文献类型：
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作者：
Tsuyoshi Nagasawa;K. Matsumoto;Naoya Minegishi;H. Kosaka
火焰合成纳米颗粒由于具有规模化生产能力和通过调节合成参数控制纳米颗粒结构的潜力而受到广泛关注。在本研究中，采用火焰辅助喷雾热解（FASP）方法，在CH4-N2/ o2 - n2燃烧器扩散火焰中提供雾化的前驱体液滴，合成了Pt/ ceo2纳米颗粒，并将其用作具有高热稳定性的负载型金属催化剂。通过XRD、FE-SEM、TEM和TEM层析成像研究了前驱体浓度和火焰温度对颗粒结构的影响。在最高火焰温度retmax≈1800 K下，合成的颗粒主要由100 nm尺度的ceo2和10 nm尺度的Pt组成，以及小于10 nm的小ceo2和高度分散的Pt聚集而成。在较低的火焰温度（Tmax≈1550 K）下，大颗粒的生成占主导地位，而在较高的火焰温度（Tmax≈2000 K）下，大多数颗粒都是小颗粒，这表明大颗粒和小颗粒分别是由液滴和气体到颗粒的路径形成的。大体积Pt/ ceo_2的TEM层析发现，Pt颗粒在ceo_2内部或部分嵌入ceo_2表面，并且在较低火焰温度下ceo_2具有多晶结构。当火焰温度从1800 K降低到1550 K时，大ceo_2中Pt的平均尺寸从10.4 nm减小到5.5 nm，而ceo_2的尺寸变化不明显。另一方面，当前驱体浓度降低1/10时，CeO2size从134 nm减小到81.5 nm，对Pt尺寸没有显著影响。最后，从ceo2和Pt纳米颗粒的晶粒生长和烧结的角度讨论了颗粒的形成机制。
Flame synthesis of nanoparticles has received much attention due to its scalable production ability and potential for controlling nanoparticle structure by adjusting synthesis parameters. In this study, Pt/CeO2nanoparticles are synthesized by flame-assisted spray pyrolysis (FASP) using a CH4-N2/O2-N2burner diffusion flame supplied with atomized precursor droplets toward application as a supported metal catalyst with high thermal stability. The effect of precursor concentration and flame temperature on particle structure is investigated through XRD, FE-SEM, TEM, and TEM tomography. The synthesized particles mainly consist of 100 nm-scale CeO2with 10 nm-scale Pt and aggregation of small CeO2less than 10 nm with highly dispersed Pt at a maximum flame temperatureTmax≈ 1800 K. At lower flame temperature (Tmax≈ 1550 K), generation of large particles are dominant while most are small at higher flame temperature (Tmax≈ 2000 K), which indicates that large and small particles are made from droplet- and gas-to-particle routes, respectively. TEM tomography of large Pt/CeO2has disclosed that Pt particles are inside of CeO2or partially embedded on the CeO2surface and also that CeO2at lower flame temperature has a polycrystalline structure. Average Pt size in large CeO2reduces from 10.4 to 5.5 nm with decreasing flame temperature from 1800 to 1550 K while CeO2size does not change significantly. On the other hand, 1/10 lower precursor concentration results in reduction of CeO2size from 134 to 81.5 nm and has no significant effect on Pt size. Finally, particle formation mechanisms are discussed from a view point of grain growth and sintering of CeO2and Pt nanoparticles.