From p- to n-type conductivity: Enhanced CO₂ sensing and optoelectronic properties of Ag/Pb-doped SnS nanocomposites

The present research investigates the synthesis and characterization of Ag/Pb-doped SnS nanocomposites for optoelectronic and CO₂ sensing applications. The nanocomposites were synthesized using a sonochemical method with varying Ag concentrations (Ag1, Ag2, Ag3) and 6 % Pb doping, followed by structural, morphological, and optoelectronic analyses. Optical properties revealed a decrease in the energy band gap with Ag incorporation, enhancing photoluminescence (PL) intensity and defect emissions, which can improve charge transport and photocurrent generation. The study of electrical and optoelectronic properties shows a change in electrical conductivity from p- to n-type with the addition of Ag concentrations. Gas sensing measurements demonstrated enhanced performance of Ag/Pb-doped samples for CO₂ detection at 200 ppm and 180 °C, with the Ag2 sample exhibiting the best response. The improved sensing capabilities are attributed to the enhanced surface area and defect density, which increased gas adsorption sites and charge transfer efficiency. This study suggests that Ag/Pb-doped SnS nanocomposites are promising for optoelectronic devices and gas sensors, with the potential to detect CO₂ in industrial and environmental applications.