Fabrication of three-dimensional flower-ball heterostructures MoS2/LDHs based on an interface coupling strategy and their application in high-performance NOx gas sensing

Abstract

To address the core challenges of high cost and low sensitivity in gas sensing, a three-dimensional flower-ball MoS₂/LDHs sensing material with rapid responsiveness to NO_x was fabricated via a facile hydrothermal approach. When detecting 100 ppm NO_x, the MoS₂/LDHs sample with a Co-to-Al molar ratio of 2 : 1 exhibits a response value of 28.31, with a response time of merely 2.13 seconds and a detection limit as low as 30 ppb. Its unique morphological structure confers a specific surface area of 77.41 m² g⁻¹ upon the MoS₂/LDHs material, providing a considerable number of active sites for NO_x adsorption. As demonstrated by XPS and EPR characterisation, the abundant adsorbed oxygen species and oxygen vacancy defects within the material synergistically facilitate the effective adsorption of NO_x, thereby enhancing the material's sensing response. Furthermore, the formation of p–p heterojunctions improves the efficiency of electron transfer from LDHs to MoS₂, ultimately boosting the detection sensitivity towards NO_x.