Synergistic Effects of PdOx-CuOx Loadings on Methylmercaptan Sensing of Porous WO3 Microspheres Prepared by Ultrasonic Spray Pyrolysis.

In this work, the PdOx-CuOx co-loaded porous WO3 microspheres were synthesized with varying loading levels by ultrasonic-spray pyrolysis (USP) using polymethylmethacrylate (PMMA) microspheres as a vehicle template. The as-prepared sensing materials and their fabricated sensor properties were characterized by X-ray analysis, nitrogen adsorption, and electron microscopy. The gas-sensing properties were studied towards methylmercaptan (CH3SH), hydrogen sulfide (H2S), dimethyl sulfide (CH3SCH3), nitric oxide (NO), nitrogen dioxide (NO2), methane (CH4,), ethanol (C2H5OH) and acetone (C3H6O) at 0.5 ppm under atmospheric conditions with different operating temperatures ranging from 100‒400°C. The results showed that the CH3SH response of USP-made WO3 microspheres were collaboratively enhanced by the creation of pores in the microsphere and co-loading of CuOx and PdOx at low operating temperatures (≤ 200°C). More importantly, the CH3SH selectivity against H2S was significantly improved and high selectivity against CH3SCH3, NO, NO2, CH4, C2H5OH and CH3COCH3 were upheld by the incorporation of PdOx to CuOx-loaded WO3 sensors. Therefore, the co-loading of PdOx-CuOx on porous WO3 structures could be promising strategies to achieve highly selective and sensitive CH3SH sensors, which would be practically useful for specific applications including biomedical and periodontal diagnoses.

[1]  Han‐Ki Kim,et al.  Deposition Rate Effect on Optical and Electrical Properties of Thermally Evaporated WO3−x/Ag/WO3−x Multilayer Electrode for Transparent and Flexible Thin Film Heaters , 2020, Scientific Reports.

[2]  Jianzhi Gao,et al.  Nanoscale Pd catalysts decorated WO3–SnO2 heterojunction nanotubes for highly sensitive and selective acetone sensing , 2020 .

[3]  Xiaobing Hu,et al.  Highly sensitive and selective H2S gas sensors based on flower-like WO3/CuO composites operating at low/room temperature , 2019, Journal of Alloys and Compounds.

[4]  Y. Shimizu,et al.  Improvement in NO2 Sensing Properties of Semiconductor-Type Gas Sensors by Loading of Au Into Porous In2O3 Powders , 2019, Front. Mater..

[5]  D. E. Motaung,et al.  Reduction-oxidation of V2O5-WO3 nanostructured by ball milling and annealing: Their improved H2S gas sensing performance , 2019, Applied Surface Science.

[6]  R. Wu,et al.  Preparation of palladium-doped mesoporous WO3 for hydrogen gas sensors , 2019, Journal of Alloys and Compounds.

[7]  Y. Shimizu,et al.  H2S Sensing Properties and Mechanism of Macroporous Semiconductor Sensors , 2008, ECS Transactions.

[8]  Y. Shimizu,et al.  Enhancement of methylmercaptan sensing response of WO3 semiconductor gas sensors by gas reactivity and gas diffusivity , 2018, Sensors and Actuators B: Chemical.

[9]  E. Fortunato,et al.  Visualization of nanocrystalline CuO in the grain boundaries of Cu2O thin films and effect on band bending and film resistivity , 2018, APL Materials.

[10]  Zhiguang Guo,et al.  Characteristics of binary WO3@CuO and ternary WO3@PDA@CuO based on impressive sensing acetone odor. , 2018, Journal of colloid and interface science.

[11]  A. Kaur,et al.  Temperature dependent selective detection of hydrogen and acetone using Pd doped WO3/reduced graphene oxide nanocomposite , 2018, Chemical Physics Letters.

[12]  Xiaobing Hu,et al.  Highly sensitive H2S gas sensors based on Pd-doped CuO nanoflowers with low operating temperature , 2017 .

[13]  Palaniswamy Suresh Kumar,et al.  Electrodeposition of WO3 nanostructured thin films for electrochromic and H2S gas sensor applications , 2017 .

[14]  Y. Shimizu,et al.  Microstructural control of porous In2O3 powders prepared by ultrasonic-spray pyrolysis employing self-synthesized polymethylmethacrylate microspheres as a template and their NO2-sensing properties , 2017 .

[15]  G. Picasso,et al.  Sensors based on Ag-loaded hematite (α-Fe2O3) nanoparticles for methyl mercaptan detection at room temperature , 2017 .

[16]  A. Maldonado,et al.  CO Gas Sensing Properties of Pure and Cu-Incorporated SnO2 Nanoparticles: A Study of Cu-Induced Modifications , 2016, Sensors.

[17]  S. Phanichphant,et al.  Ultra-responsive hydrogen gas sensors based on PdO nanoparticle-decorated WO3 nanorods synthesized by precipitation and impregnation methods , 2016 .

[18]  Soo-Hyun Kim,et al.  Acetone sensing of Au and Pd-decorated WO3 nanorod sensors , 2015 .

[19]  R. Gordon,et al.  Band offsets of n-type electron-selective contacts on cuprous oxide (Cu2O) for photovoltaics , 2014 .

[20]  Seon-Jin Choi,et al.  The stability, sensitivity and response transients of ZnO, SnO2 and WO3 sensors under acetone, toluene and H2S environments , 2014 .

[21]  B. Liu,et al.  Improved room-temperature hydrogen sensing performance of directly formed Pd/WO3 nanocomposite , 2014 .

[22]  Andrey Shchukarev,et al.  Room temperature hydrogen sensors based on metal decorated WO3 nanowires , 2013 .

[23]  E. López-Cuéllar,et al.  Synthesis of WO3 nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties , 2013 .

[24]  K. Hadidi,et al.  XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referenc , 2011 .

[25]  Y. Shimizu,et al.  Preparation of macroporous semiconductor gas sensors and their odur sensing properties (特集 VOCガスのセンシング) , 2008 .

[26]  L. Feenstra,et al.  A review of the current literature on aetiology and measurement methods of halitosis. , 2007, Journal of dentistry.

[27]  Fredrik Svedberg,et al.  Photoelectron Spectroscopy of Nickel, Palladium, and Platinum Oxide Anions , 2002 .