Hierarchical bimetallic MOF-derived ZnO/NiO with abundant mesopores for high-performance triethylamine gas sensing

Abstract

Hierarchical bimetallic metal organic frameworks (MOFs) derived mesoporous ZnO/NiO heterostructures with excellent triethylamine (TEA) gas sensing performance were prepared. The introduction of Ni ions in MOF precursors played an important role in regulating the chemical composition and morphology evolution of ZnO/NiO heterostructures. The resultant ZnO/NiO nanocomposites contain abundant mesopores formed by accumulation of nanoparticles and a large specific surface area, providing sufficient active sites and gas diffusion channels. As predicted, compared with pure ZnO, the highly porous ZnO/NiO heterostructure exhibited enhanced TEA gas sensitivity with R_a/R_g = 49.8 at an operating temperature of 200 °C, fast response time of 11 s, as well as excellent anti-interference ability and long-term stability. The high TEA gas sensing performance can be attributed to the formation of p-n heterojunction with reduced band gap (2.81 eV), high specific surface area (43.456 m² g⁻¹) and high porosity achieved through using MOFs as a self-sacrificing template. Additionally, the increase of oxygen vacancy and the efficient oxidation-reduction reaction with the target gas also contribute significantly to the enhanced performance. This study presents a straightforward strategy for preparing mesoporous multi-metal oxide heterostructure using MOFs as sacrificial templates, offering tunable pathways to tailor and improve TEA gas sensing performance.