Green Synthesis and Sensing Assessment of HfO2 Nanoparticles for Detecting Liquid NH3 Using Electrochemical Impedance Spectroscopy

Abstract

Now-a-days, green synthesis is gaining popularity over conventional synthesis methods as it is environment-friendly, cost-effective, and less toxic. Here, we synthesized hafnium oxide (HfO2) nanoparticles using orange peel extracts (OPEs, 1, 2, and 4 wt%) for the first time. HfO2 synthesized with 4 wt% OPE and calcined at 900 °C for 1 h (HO-4-OPE) showed well dispersed nanoparticles with maximum yield. The average crystallite size of HO-4-OPE was found to be 34 nm. A sensing framework to detect liquid NH3 was developed using HfO2 nanoparticle coated electrode and electrochemical impedance spectroscopy. An exponential relation between charge transfer resistance and NH3 concentration with high R2 (0.99) was found. A prediction model based on charge transfer resistance showed an R2 value of 0.95 to predict liquid NH3. This initial assessment of the NH3 sensor shows promises for such sensors. © 2017 IEEE.