title: Facile Approach to Synthesize Au@ZnO Core-Shell Nanoparticles and Their Application for Highly Sensitive and Selective Gas Sensors.
abstract: We successfully prepared Au@ZnO core-shell nanoparticles (CSNPs) by a facile low-temperature solution route and studied its gas-sensing properties. The obtained Au@ZnO CSNPs were carefully characterized by X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, and UV-visible spectroscopy. Mostly spherical-shaped Au@ZnO CSNPs were formed by 10-15 nm Au NPs in the center and by 40-45 nm smooth ZnO shell outside. After the heat-treatment process at 500 °C, the crystallinity of ZnO shell was increased without any significant change in morphology of Au@ZnO CSNPs. The gas-sensing test of Au@ZnO CSNPs was examined at 300 °C for various gases including H2 and compared with pure ZnO NPs. The sensor Au@ZnO CSNPs showed the high sensitivity and selectivity to H2 at 300 °C. The response values of Au@ZnO CSNPs and pure ZnO NPs sensors to 100 ppm of H2 at 300 °C were 103.9 and 12.7, respectively. The improved response of Au@ZnO CSNPs was related to the electronic sensitization of Au NPs due to Schottky barrier formation. The high selectivity of Au@ZnO CSNPs sensor toward H2 gas might be due to the chemical as well as catalytic effect of Au NPs.
authors.affiliation: †Division of Advanced Materials Engineering and Research Centre for Advanced Materials Development, College of Engineering, Chonbuk National University, Jeonju 561-756, South Korea.
authors.forename: Sanjit Manohar
authors.initials: SM
authors.lastname: Majhi
authors.affiliation: ‡Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
authors.forename: Prabhakar
authors.initials: P
authors.lastname: Rai
authors.affiliation: †Division of Advanced Materials Engineering and Research Centre for Advanced Materials Development, College of Engineering, Chonbuk National University, Jeonju 561-756, South Korea.
authors.forename: Yeon-Tae
authors.initials: YT
authors.lastname: Yu
keywords: Au@ZnO; H2; Schottky junction; core−shell nanoparticles; sensitivity