Rapid response with low limit detection H2S sensors based on Ni/MWCNTs/CuO/Fe2O3 at room temperature

In this study, Ni/MWCNTs/CuO/Fe 2 O 3 composite nanomaterials were synthesised by a simple hydrothermal method, using Fe 2 O 3 as a substrate material and taking advantage of the excellent properties of carbon nanotubes, which possess a large surface area, and the catalytic ability of Ni. These nanocomposites are easy to synthesise and cost-effective. Compared to CuO/Fe 2 O 3 and MWCNTs/CuO/Fe 2 O 3 , Ni/MWCNTs/CuO/Fe 2 O 3 exhibits higher sensitivity and response values for H 2 S at room temperature. In particular, the best performance was achieved when the content of Ni/MWCNTs was 5 wt%. The sensing material, featuring a short response/recovery time (4 s/10 s), a low lower limit of detection (10 ppb), a high response value (100 ppm, 125), and high selectivity, is an excellent detection material for H 2 S. The enhanced performance of the composites can be attributed to several factors. Firstly, the formation of multiple heterojunctions and Schottky barriers facilitates electron transfer. Secondly, the interconnection of the conductive backbones of the MWCNTs increases the area of mutual contact, thereby providing more active sites for the reaction. Lastly, the highly efficient electrocatalysis of Ni reduces the activation energy of the reaction, accelerating the reaction kinetics, which in turn improves the gas-sensitive performance of the sensing materials for H 2 S.