Rapid Response with Low Limit Detection H2S Sensors Based on Ni/MWCNTs/CuO/Fe2O3 at Room Temperature

In this study, Ni/MWCNTs/CuO/Fe₂O₃ composite nanomaterials were synthesised by a simple hydrothermal method, using Fe₂O₃ 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/Fe₂O₃ and MWCNTs/CuO/Fe₂O₃, Ni/MWCNTs/CuO/Fe₂O₃ exhibits higher sensitivity and response values for H₂S 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 H₂S. 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 H₂S.