A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods
Abstract
:1. Introduction
2. Materials and Methods
2.1. Preparation of Former Pure SnO2 Powders Using Urea and Ammonia
2.2. Preparation of Chemical Doped SnO2 Powders
2.3. Preparation of Impregnated SnO2 Powders
2.4. Characterization
3. Results
3.1. X-ray Diffraction Analysis
3.2. Raman Analysis
3.3. SEM Analysis
3.4. HRTEM Analysis
3.5. CO Sensing Properties
4. Discussion
Gas-Sensing Mechanism
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Name of the Sample | Doping Method | Precipitation Agent | Dopant |
---|---|---|---|
Cu:SnO2_U_Chem | Chemical doping | Urea | Cu |
Cu:SnO2_A_Chem | Chemical doping | Ammonia | |
Cu:SnO2_U_Impe | Impregnation | Urea | |
Cu:SnO2_A_Impe | Impregnation | Ammonia | |
Pt:SnO2_U_Chem | Chemical doping | Urea | Pt |
Pt:SnO2_A_Chem | Chemical doping | Ammonia | |
Pt:SnO2_U_Impe | Impregnation | Urea | |
Pt:SnO2_A_Impe | Impregnation | Ammonia | |
Pd:SnO2_U_Chem | Chemical doping | Urea | Pd |
Pd:SnO2_A_Chem | Chemical doping | Ammonia | |
Pd:SnO2_U_Impe | Impregnation | Urea | |
Pd:SnO2_A_Impe | Impregnation | Ammonia |
Sample Name | D (nm) | V (10−24 cm3) | P (%) |
---|---|---|---|
SnO2_U | 26.3 | 71.4 | 32.3 |
SnO2_A | 30.0 | 71.6 | 32.4 |
Cu:SnO2_U_Chem | 21.2 | 71.7 | 58.4 |
Cu:SnO2_A_Chem | 21.0 | 71.7 | 58.5 |
Cu:SnO2_U_Impe | 22.2 | 71.7 | 58.5 |
Cu:SnO2_A_Impe | 22.0 | 71.8 | 58.7 |
Pt:SnO2_U_Chem | 35.0 | 71.8 | 64.6 |
Pt:SnO2_A_Chem | 35.0 | 71.8 | 64.7 |
Pt:SnO2_U_Impe | 33.0 | 71.8 | 64.8 |
Pt:SnO2_A_Impe | 33.0 | 71.9 | 64.8 |
Pd:SnO2_U_Chem | 42.0 | 72.0 | 73.0 |
Pd:SnO2_A_Chem | 42.0 | 72.0 | 73.0 |
Pd:SnO2_U_Impe | 40.0 | 72.0 | 73.0 |
Pd:SnO2_A_Impe | 40.0 | 72.2 | 73.2 |
Modes | Notation | Direction of Vibration with Respect to c-Axis | Raman Shift (cm−1) |
---|---|---|---|
Raman active | A1g | Perpendicular | 638 |
B1g | Perpendicular | 100 | |
B2g | Perpendicular | 782 | |
Eg | Parallel | 476 | |
IR active | A2u | Parallel | 705 |
Eu | Perpendicular | 244 | |
Silent | A2g | Perpendicular | 398 |
B1u | Parallel | 140 |
Dopant | SnO2–d (110) in Å | |||||
---|---|---|---|---|---|---|
Urea | Ammonia | Chemically Doped | Impregnated Powders | |||
Urea | Ammonia | Urea | Ammonia | |||
Undoped | 3.35853 | 3.35492 | - | - | - | - |
Cu | - | - | 3.3732 | 3.36927 | 3.3682 | 3.3927 |
Pt | - | - | 3.39422 | 3.38839 | 3.3801 | 3.35427 |
Pd | - | - | 3.41855 | 3.40501 | 3.40697 | 3.35706 |
Undoped | Cu | Pt | Pd | |
---|---|---|---|---|
U_Chem | 12 | - | - | - |
A_Chem | 10 | - | - | - |
U_Chem | 1782.609 | 1200 | 502.5 | |
A_Chem | 1625 | 721.519 | 287.6405 | |
U_Impe | 1666.667 | 428.7234 | 245.4546 | |
A_Impe | 975.7412 | 387.3333 | 224.1485 |
SnO2 Synthesis Method | SnO2 Precursor | Crystallite Size (nm) | Sensing Response (Ra/Rg at Specified Operating Temperature and Mole Fraction of Target Gas) | Reference |
---|---|---|---|---|
Vapor−liquid−solid | Sn Powder | ~75–90 | ~ 80 at 300 °C and at 10 ppm of CO | [61] |
Hydrothermal process | SnCl2·2H2O | ~10 | ~ 78 at 220 °C and at 100 ppm of acetone | [62] |
Hydrolysis and Precipitation | SnCl4·5H2O | ~15 | ~80 at 350 °C and at 600 ppm of CO | [63] |
Chemical spray pyrolysis | SnCl4·5H2O | ~10 | ~132 at 225 °C and at 400 ppm of NO2 | [64] |
Precipitation | SnCl4·5H2O | ~14 | ~100 at 350 °C and at 600 ppm of CO | [65] |
One-step Solvothermal route | SnCl4·5H2O | ~10 | ~22.69 at 260 °C and at 50 ppm of ethanol gas | [66] |
Sol-Gel | SnCl4·5H2O | ~8–20 | ~1.95 at 100 °C and at 5 ppm of CO | [67] |
Hydrothermal synthesis | SnCl4·5H2O | ~3.4 ± 0.8 nm | ~357 at 100 °C and at 5 ppm of H2S | [68] |
Present work | SnCl4·5H2O | ~35 | ~1782 at 300 °C and at 300ppm | -- |
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Tangirala, V.K.K.; Gómez-Pozos, H.; Rodríguez-Lugo, V.; Olvera, M.D.L.L. A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods. Sensors 2017, 17, 1011. https://doi.org/10.3390/s17051011
Tangirala VKK, Gómez-Pozos H, Rodríguez-Lugo V, Olvera MDLL. A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods. Sensors. 2017; 17(5):1011. https://doi.org/10.3390/s17051011
Chicago/Turabian StyleTangirala, Venkata Krishna Karthik, Heberto Gómez-Pozos, Ventura Rodríguez-Lugo, and María De La Luz Olvera. 2017. "A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods" Sensors 17, no. 5: 1011. https://doi.org/10.3390/s17051011
APA StyleTangirala, V. K. K., Gómez-Pozos, H., Rodríguez-Lugo, V., & Olvera, M. D. L. L. (2017). A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods. Sensors, 17(5), 1011. https://doi.org/10.3390/s17051011