Selective recognition of hydrogen sulfide using template and catalyst free grown ZnO nanorods

Abstract

Hydrogen sulfide is one of the important endogenous signaling molecules which can play a key role in regulating blood pressure, cardiovascular and age-associated diseases. But it is extremely toxic if inhaled externally and even can cause death at higher concentrations. This work reports a systematic investigation of template and catalyst free grown ZnO nanorods through simple chemical spray pyrolysis technique and their room temperature hydrogen sulfide sensing characteristics such as sensitivity, selectivity, stability, response and recovery times. The structural, morphological, optical and electrical properties of ZnO nanostructures were investigated using X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), UV-vis spectrophotometer and electrometer respectively. The role of density of nanorods formed on the glass substrates through spray cycle modulation has been used as an effective tool for achieving better sensing response. ZnO nanorods with the diameter ranging from 200 -250 nm exhibited high selectivity towards hydrogen sulfide and the mechanism has been reported. The challenge of selectivity has also been solved efficiently through ZnO nanorods.

Tuning selectivity through cobalt doping in spray pyrolysis deposited ZnO thin films

“…The electrical properties like sheet carrier concentration, mobility and carrier type were measured using Hall effect system (HMS 3000, Ecopia, South Korea) employing standard van-der Pauw method. Gas sensing properties were studied using high resistance electrometer (Keithley 6517 A, USA) integrated with home-made gas sensing chamber [20,24,25]. Prior to sensing studies, the film was cut into smaller pieces of 1 Â 1 cm 2 using diamond cutter.…”

“…Then the sensing elements were placed inside the testing chamber and necessary electrical contacts were made. The target gas concentration [25] was fixed inside the testing chamber using Eq. (1),…”

“…been in intense focus towards developing better sensing devices [9][10][11][12][13][14][15][16][17][18][19]. ZnO based chemiresistive sensors have shown promising results with excellent sensing properties towards ammonia [20][21][22][23], acetaldehyde [24], hydrogen sulfide [25,26], ethanol [27,28] and ethanolamine [29] at room temperature. Since, gas sensing is a surface phenomenon, the sensing characteristics of the solid can be enhanced by modifying the surface and electrical properties through various synthesis methods with and without dopants.…”

ZnO nanoarchitectures: Ultrahigh sensitive room temperature acetaldehyde sensor

“…Initially, Ohmic contacts were established on the surface of the sensing element (10 mm × 10 mm) using zero resistance copper wires and highly conducting silver paste.Sensing studies were carried out at room temperature using custom build gas sensing setup and the same described in our previous report [30][31][32]. The concentration of the target vapour [26] in the testing chamber was fixed using Eq. 1.…”

“…Complex morphologies have drawn much attention in gas sensor field due to their excellent properties like high surface area and enhanced surface catalytic activity [24][25][26]. As of now, seeded growth technologies have been used to prepare various ZnO nanoarchitectures especially complex morphologies like branched nanorods [27][28][29].…”