Enhanced H₂S gas sensing properties of Mn doped ZnO nanoparticles—an impedance spectroscopic investigation

Review—Recent Advances in Electrochemical Impedance Spectroscopy Based Toxic Gas Sensors Using Semiconducting Metal Oxides

“…This clearly indicates that sensitivity is based on the charge grain and the authors concluded that Mn doped ZnO reveals the high response to H 2 S (2-100 ppm) toxic gas with response and recovery time at 22 s and 19 s, respectively. 72 The authors also reported that Mn sensitized SnO 2 for H 2 S gas (2-50 ppm) sensor at room temperature following the previous experimental procedure. They were able to obtain a sensor with a response (∼6 s) and recovery (∼8 s) with high selectivity towards other gases.…”

“…Electrochemical impedance was recorded with a frequency range from high to low (1 MHz to 1 Hz) and 10 mV sinus amplitude and without dc bias. 72 The Nyquist plot in Fig. 7a clearly indicates impedance diameter of semicircle decreases with the increase in H 2 S gas (2-100 ppm) concentration.…”

“…Spin coating based gas sensor.-Suresh kumar et al 72 reported the use of Mn doped and pure ZnO sensing materials coated on alumina substrate for H 2 S toxic gas sensing applications. Electrochemical impedance was recorded with a frequency range from high to low (1 MHz to 1 Hz) and 10 mV sinus amplitude and without dc bias.…”

“…7c. The equivalent circuit contained the following elements, 72 R 1 -Resistance between silver electrode and sensing films, C 2 , R 2 -Grain bulk capacitance and resistance, C 3 , R 3 -Grain boundaries respective capacitance and resistance of Mn:ZnO grains.…”

“…The fitted values was reported 72 with respect to concentrations of H 2 S gas and this clearly indicates decrease of R 1 , R 2 and R 3 with the increase in C 1 , C 2 , C 3 and particularly R 2 compared with R 1 and R 3 values drastically decreased with the increase in the concentration of H 2 S. This signifies that grain boundary resistance values are slightly decreased when compared to grain bulk and resistance between silver electrode and sensing films. It can be further noted that in Fig.…”