Microfluidically synthesized Au, Pd and AuPd nanoparticles supported on SnO2 for gas sensing applications

SENSORS AND ACTUATORS B-CHEMICAL

卷:292

Article

Tofighi, Ghazal¹  Degler, David^2,3,6  Junker, Benjamin^2,3  Mueller, Sabrina¹  Lichtenberg, Henning^1,4  Wang, Wu⁵  Weimar, Udo^2,3  Barsan, Nicolae^2,3  Grunwaldt, Jan-Dierk^1,4 

[1] Karlsruhe Inst Technol, Inst Chem Technol & Polymer Chem ITCP, Engesserstr 20, D-76131 Karlsruhe, Germany

[2] Univ Tubingen, Inst Phys & Theoret Chem, D-72076 Tubingen, Germany

[3] Univ Tubingen, Ctr Light Matter Interact Sensors & Analyt LISA, D-72076 Tubingen, Germany

[4] Karlsruhe Inst Technol, Inst Catalysis Res & Technol IKFT, D-76344 Eggenstein Leopoldshafen, Germany

[5] Karlsruhe Inst Technol, Inst Nanotechnol INT, D-76344 Eggenstein Leopoldshafen, Germany

[6] European Synchrotron Radiat Facil, F-38043 Grenoble, France

关键词: Microfluidic synthesis;    AuPd nanoalloy;    Gold;    Palladium;    SnO2;    Gas sensor;   

DOI  :  10.1016/j.snb.2019.02.107

来源: Elsevier

【 摘 要 】

Monometallic Au and Pd nanoparticles (NPs) and homogeneous AuPd nanoalloy particles were synthesized in a continuous flow of reactants (HAuCl4, K2PdCl4, NaBH4 and polyvinylpyrrolidone (PVP)) using a microfluidic reactor with efficient micromixers. The obtained ultrasmall NPs were subsequently deposited onto SnO2 supports with different surface area (32.7 and 3.6 m(2)g(-1)). Samples with 1.0 and 0.1 wt% metal loading were prepared. After calcination at 380 degrees C for 1 h the supported NPs aggregated to some extent. SnO2 supported AuPd nanoalloys with low (0.1 wt. %) metal loadings showed the smallest NP diameters ((similar to)5-7 nm) and the narrowest size distribution among the samples. The gas sensing performance of the materials was investigated at 300 degrees C in four different gas atmospheres containing either CO, CH4, ethanol or toluene using dry and humid conditions. They exhibited a distinct variation in the response patterns and selectivity toward the test gases depending on composition and metal loading: Au increased the sensor signals compared to pristine SnO2 in all cases and decreased the interference of water vapor; the supported Pd NPs showed a weak response to toluene, strong sensitivity in CO sensing and slightly better response in ethanol sensing in humid air compared to dry air. However, they showed a high selectivity toward CH4 when used in dry air; AuPd alloy particles provided lower sensor signals compared to pristine SnO2 and no remarkable CH4 selectivity, in contrast to the Pd system. Operando diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS) and DC-resistance measurements indicate a strong band bending in the case of Pd and AuPd NPs, whereas in the case of Au no band bending occured, indicating a strong electronic interaction between the support and Pd-containing NPs (Fermi-level control mechanism), and a weak electronic interaction between SnO2 and Au NPs (spill-over mechanism).

【 授权许可】

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