A versatile hydrogen gas sensor is fabricated using Pd@ZnO core-shell nanoparticles (CSNPs), which were synthesized through a hydrothermal route. Effect of oxidation behavior of Pd core to hydrogen sensing is also investigated for Pd@ZnO CSNPs. Accordingly, Pd@ZnO-2 sensor (core-shell sample was calcined in argon) demonstrates the best performance with respect to Pd@ZnO-1 (core-shell sample was calcined in air) and pure ZnO. It shows a much higher response (R = Ra/Rg = 22) than those of Pd@ZnO-1 (12) and pure ZnO (7) sensors with faster response and recovery times (1.4 and 7.8 min) to 100 ppm hydrogen at 350 °C. In addition, Pd@ZnO-2 sensor owns high selectivity to hydrogen among interfering target gases. Improvement can be attributed to the high content of metallic Pd0 species in CSNPs as calcined in argon. Thereby, a higher Pd metallic content (77%) still remains in Pd@ZnO-2 compared to Pd@ZnO-1 (56%), which in turn modulates the resistance of sensors as exposed to air and target gas, thus enhancing gas sensing activity. High BET surface area of core-shell materials provides plenty of active sites for accelerating the sensing reactions as well.
Bibliographical noteFunding Information:
This work was supported by 1) the BK21-FOUR program of the Ministry of Education and Human-Resource Development, South of Korea; 2) a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (2016R1A2B4014090, 2020R1A2B5B03001603); and 3) Research Base Construction Fund Support Program by Jeonbuk National University in 2018.
© 2020 Elsevier Inc.
- Hydrogen sensing
- Surface area
- Zinc oxide
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry