MOF-Derived Porous Hollow Co₃O₄@ZnO Cages for High-Performance MEMS Trimethylamine Sensors

Abstract

Trimethylamine (TMA) sensors based on metal oxide semiconductors (MOS) have drawn great attention for realtime seafood quality evaluation. However, poor selectivity and baseline drift limit the practical applications of MOS TMA sensors. Engineering core@shell heterojunction structures with accumulation and depletion layers formed at the interface is regarded as an appealing way for enhanced gas sensing performances. Herein, we design porous hollow Co 3 O 4 @ZnO cages via a facile ZIF-67@ZIF-8-derived approach for TMA sensors. These sensors demonstrate great TMA resistive sensing performance (linear response at moderate TMA concentrations (<33 ppm)), and a high sensitivity of ∼41 is observed when exposed to 33 ppm TMA, with a response/recovery time of only 3/2 s. This superior performance benefits from the Co 3 O 4 @ZnO porous hollow structure with maximum heterojunctions and high surface area. Furthermore, great capacitive TMA sensing with linear sensitivity over the full testing concentration range (0.33−66 ppm) and better baseline stability were investigated. A possible capacitive sensing mechanism of TMA polarization was proposed. For practical usage, a portable sensing prototype based on the Co 3 O 4 @ZnO sensor was fabricated, and its satisfactory sensing behavior further confirms the potential for real-time TMA detection.

Electrospinning Derived NiO/NiFe2O4 Fiber-in-Tube Composite for Fast Triethylamine Detection under Different Humidity

“…Three types of oxygen species (lattice oxygen, oxygen vacancy and chemisorbed oxygen) can be obtained through classifying O 1s peaks. , The lattice oxygen (O L ) is attributed to metal–oxygen bonds (M-O), including Ni–O and Fe–O. The oxygen vacancy (O V ) is attributed to nonstoichiometric defects . The chemisorbed oxygen (O C ) is the adsorbed oxygen species (O – ) on the surface.…”

“…The oxygen vacancy (O V ) is attributed to nonstoichiometric defects. 58 The chemisorbed oxygen (O C ) is the adsorbed oxygen species (O − ) on the surface. Table 1 displays the peaks fitting results according to the O 1s XPS spectra of all samples.…”

Porous Pb-Doped ZnO Nanobelts with Enriched Oxygen Vacancies: Preparation and Their Chemiresistive Sensing Performance

“…Figure 4d displays the high-resolution O 1s XPS spectra of 0.61 at% Pb-doped ZnO porous nanobelts. Here, its peak can be deconvoluted into four types of peaks: the peak of lattice O of ZnO (O Zn ) at around 530.2 eV, the peak situated at 530.37 eV represents the lattice O of PbO (O Pb ), the peak located at around 530.66 eV attributed to the oxygen vacancy (O va ), and the peak at a binding energy of 531.68 eV assigned to the adsorbed oxygen (O ad ) [30]. The similar analysis procedure of deconvolution and fitting was also applied to the high-resolution O 1s XPS spectra of pure ZnO porous nanobelts in Figure 4e.…”

“…and the peak at a binding energy of 531.68 eV assigned to the adsorbed oxygen (Oad) [30]. The similar analysis procedure of deconvolution and fitting was also applied to the highresolution O 1s XPS spectra of pure ZnO porous nanobelts in Figure 4e.…”

Highly sensitive and fast-response ethanol sensing of porous Co3O4 hollow polyhedra via palladium reined spillover effect

“…For examples, Masuda et al 10 successfully synthesized highly porous CuO nanostructures by converting Cu-MOF precursor, which could detect a tiny concentration of acetone gas up to 50 ppb. Zhang et al 11 fabricated porous hollow Co 3 O 4 @ZnO cages through ZIF-67@ZIF-8-derived process, which exhibited a high sensitivity of ∼41 with a response/recovery time of only 3/2 s for 33 ppm trimethylamine.…”