Synthesis of amorphous ZnO–SiO2 nanocomposite with enhanced chemical sensing properties

• Amorphous SiO2 with no peaks of ZnO wurtzite structure was formed.
• ZnO–SiO2 has a large surface area of 462 m2/g.
• ZnO–SiO2 was employed for the detection of phenyl hydrazine as chemical sensor.
• The sensitivity and the limit of detection were 10.80 μA cm− 2 mM− 1 and 1.42 μM.
• The modified ZnO–SiO2 nanocomposite sensor electrode was extremely stable.

Amorphous zinc oxide–silica (a-ZnO–SiO2) nanocomposite has been synthesized using a sol–gel process. X-ray diffraction patterns show a broad diffraction peak of amorphous SiO2 with no peaks related to ZnO wurtzite structure. ZnO–SiO2 nanocomposite posses uniformly spherical particles and large surface area 462 m2/g. The prepared a-ZnO–SiO2 nanocomposite was used as a chemical sensor to detect phenyl hydrazine via a simple electrochemical technique by measuring the current–potential (I–V) characteristics. The calibration curve exhibits good linearity over all concentration range from 390 μM to 50 mM (r2 = 0.9986) and the limit of detection was estimated to be 1.42 μM. The sensitivity was calculated to be 10.80 μA cm− 2 mM− 1 as a result of good adsorption ability and large surface area of the prepared sensor. Interestingly, the modified ZnO–SiO2 nanocomposite sensor electrode was extremely stable during the sensing runs, since no significant sensitivity decrease was observed after being re-used for five times. Furthermore, no deterioration in the I–V characteristics was detected after being stored in ambient conditions for three months, indicating the fabricated sensor exhibited long term stability.