Enhanced ammonia gas sensing properties in porous multiwalled carbon nanotubes decorated with metal nanoparticles: the impact of concentration of Mn

Abstract In this work, the fabrication and comparison of distinct types of multi-walled carbon nanotube-based gas sensing devices on N type (100) silicon substrates for the detection of low ammonia concentrations are reported. Every measurement was made at room temperature. The whole process was tested at 10 ppm of ammonia gas. We have noticed the characteristics of fast response/recovery time (1–9 s) in pristine and (1–5 s) in Manganese metal (Mn) nanoparticles (99.99% purity) decorated MWCNT. The high-quality sensor response of roughly 82% has been found in pristine,177% in 2 min decorated, 73% in 4 min decorated and 130% in 6 min decorated respectively. The sensitivity of the as prepared samples comes to be 14% for the pristine, 35%, 37%, and 43% for rest of the sensors on percentage bases respectively. 75%–85% recovery was attained based on the obtained sensor response graph. The stability was also measured for a period of 7 days at constant concentration. A Keithley 6514 source meter was used for the resistance variation measurements. FESEM (Gemini 500), Raman spectroscopy (Renishaw), XRD, EDS and FTIR have been used to examine the different morphologies of the as prepared materials.