The results demonstrated that the sensors based on WO3/ZnO structures possessed larger response, better selectivity, faster response/recovery than the sensor based on pure ZnO MRs. Especially, the gas sensing property of the WO3/ZnO composite based sensor with weight ratio of 1:1 was superior to others. However, the operating temperature is quite high (400 C). The mechanism of gas sensing was also studied. | Journal of Science and Technology 54 (1A) (2016) 151-159 ZnO MICRORODS SURFACE-DECORATED BY WO3 NANORODS FOR ENHANCING NH3 GAS SENSING PERFORMANCE Nguyen Dac Dien*, Do Duc Tho, Vu Xuan Hien, Dang Duc Vuong, Nguyen Duc Chien School of Engineering Physics, Hanoi University of Science and Technology, Dai Co Viet road, Hanoi * Email: nddien1980@ Received: 14 September 2015; Accepted for publication: 25 October 2015 ABSTRACT Regularly shaped, single-crystalline ZnO microrods (MRs) with wurtzite structure were prepared via a wet chemical method. The obtained rods possess average diameter and length of 350 nm and µm, respectively. Besides, WO3 nanorods (NRs) with the size of 20 nm in diameter and 120 nm in length were synthesized by hydrothermal route. A facile solid state reaction route was employed to synthesize the WO3/ZnO structure by grinding WO3 NRs powder and ZnO MRs powder with various weight ratios (1:2, 1:1 and 2:1) together at room temperature without any surfactant and template. WO3 NRs were sprinkled on ZnO MRs surface and it was observed that the amount of WO3 significantly affected the overall surface of ZnO MRs. Furthermore, NH3 gas-sensing property of the obtained products were studied and compared with that of sole ZnO MRs sample. The results demonstrated that the sensors based on WO3/ZnO structures possessed larger response, better selectivity, faster response/recovery than the sensor based on pure ZnO MRs. Especially, the gas sensing property of the WO3/ZnO composite based sensor with weight ratio of 1:1 was superior to others. However, the operating temperature is quite high (400 C). The mechanism of gas sensing was also studied. Keywords: WO3/ZnO composite, NH3 gas sensor, hydrothermal treatment. 1. INTRODUCTION Ammonia is utilized extensively in many chemical industries, fertilizer factories, refrigeration systems, etc. It is harmful and toxic in nature and can result in health hazards such as chronic lung disease, irritating and
