Enhanced cyclohexane resistive gas sensing using Mg-doped Bi2WO6 hollow microtubes derived from selective etching of MOF

Abstract

The design of composition and morphology is a highly effective strategy for transforming solid metal–organic frameworks (MOFs) into hollow structures. In this study, we synthesized Mg-doped Bi₂WO₆ hollow tubes using bismuth metal–organic frameworks (CAU-17) as templates. This process involves the synthesis of solid CAU-17 microtubes, the etching of hollow tubes using Mg²⁺/WO₄²⁻ ions, and the formation of Mg/Bi₂WO₆ hollow microtubes through air annealing. The unique hollow structure and complex composition of Mg/Bi₂WO₆ contribute to its exceptional resistive gas sensing performance for detecting cyclohexane. The excellent cyclohexane sensing capabilities of Mg/Bi₂WO₆ are a result of the cooperative enhancement from its hollow structure (high utility factor) and Mg doping (optimized receptor and transducer functions), with its high selectivity being fundamentally governed by the favorable adsorption thermodynamics and kinetics of cyclohexane on its surface. The Mg/Bi₂WO₆ (ω_Mg = 0.2 wt.%) sensor exhibits remarkable sensitivity (50 ppm, R_a/R_g = 67), detecting cyclohexane as low as 0.1 ppm at 275 °C (R_a/R_g = 1.2). Additionally, it demonstrates excellent selectivity and outstanding stability for cyclohexane, underscoring its potential for practical applications in the clinical diagnosis of tuberculosis patients. This work presents a novel strategy for the rational design of hollow tube metal oxides with superior resistive gas sensing capabilities, paving the way for future advancements in multifunctional materials.

Graphical abstract