Generation of Oxygen Vacancies in Metal–Organic Framework-Derived One-Dimensional Ni_0.4Fe_2.6O₄ Nanorice Heterojunctions for ppb-Level Diethylamine Gas Sensing

Abstract

Metal–organic frameworks (MOFs) are ideal sensing materials due to their distinctive morphologies, high surface area, and simple calcination to remove sacrificial MOF scaffolds. Oxygen vacancies (Ovs) can be efficiently generated by the thermal annealing of metal oxides in an inert atmosphere. Herein, MIL-53-based Fe and Fe/Ni-MOFs nanorices (NRs) were first prepared by using a solvothermal method, and then one-dimensional (1D) Fe2O3 and Ni0.4Fe2.6O4 NRs were derived from the MOFs after calcination at 350 °C in an air and argon (Ar) atmosphere, respectively. It was found that Ar-annealed Ni0.4Fe2.6O4 NRs have higher Ovs concentrations (82.11%) and smaller NRs (24.3 nm) than air-annealed NRs (65.68% & 31.5 nm). Beneficially, among the synthesized NRs, the Ar-Ni0.4Fe2.6O4 NRs show a higher sensitivity to diethylamine (DEA) (R a/R g = 23 @ 5 ppm, 175 °C), low detection limit (R a/R g = 1.2 @ 200 ppb), wide dynamic response (R a/R g = 93.5@ 30 ppm), high stability (30 days), and faster response/recovery time (4 s/38 s). Moreover, the 1D nanostructure containing heterostructures offers excellent sensing selectivity and a wide detection range from 200 ppb to 30 ppm in the presence of DEA. The outstanding gas sensing behavior can be attributable to synergistic impact, structural advantages, high concentration of Ovs, and the heterojunction interface, which can have profound effects on gas sensor performance. This study provides a unique technique for constructing high-performance gas sensors for ppb-level DEA detection and the formation of Ovs in metal oxides without the need for any additives.

Integration of High-Entropy Oxide with Nitrogen-Doped Graphene for the Ultrasensitive Electrochemiluminescence Detection of Trolox and Dopamine

“…The presence of elements Mg, Co, Cu, Ni, Zn, C, N, and O was identified by XPS survey spectra, as indexed in Figure S3. The high-resolution XPS spectra of Co 2p and Ni 2p show that both metals split into two spin orbitals and shakeup satellite peaks, indicating the presence of divalent and trivalent species, with a dominance of divalent ones (Figure a,b). − The Cu 2p spectrum signifies the coexistence of monovalent and divalent species, with a dominance of divalence (Figure c), whereas the Mg 1s and Zn 2p spectra reveal also that the corresponding elements are in divalence status (Mg 2+ and Zn 2+ ; Figure d,e). The N 1s spectrum (Figure f) indicates the presence of two deconvoluted peaks credited as pyridinic N (398.6 eV) and graphitic N (402.5 eV), which is assumed to contribute to improving the stability and catalytic activity of the resulting sample .…”

Metal–organic framework-derived metal oxides for resistive gas sensing: a review

“…[37][38][39][40][41][42][43] This characteristic allows for the precise identification of target gases, increasing their dependability as gas detectors. [44][45][46][47][48][49][50][51][52][53] In addition, the large surface area and permeable structure of metal oxides derived from MOFs create a wealth of adsorption sites and pathways, allowing for effective gas-molecule interactions. [54][55][56][57][58] As a consequence, gas detection applications experience enhanced sensitivity and swift response times.…”

Ultrafast Response and High Selectivity of Diethylamine Gas Sensors at Room Temperature Using MOF-Derived 1D CuO Nano-Ellipsoids

“…24 MOF materials have undergone considerable investigation in a wide range of applications, including chemical sensors, gas storage, separation, and catalysis. 22,24 Therefore, MOFs are being explored for their possible application as selective gas sensors due to their huge surface area, clear pore structure, high metal content, and unique gas adsorption capabilities, which include functionalized sites and fascinating features such as ferroelectricity, magnetism, and conductivity. 25,26 For example, Wang et al 27 successfully fabricated ZnO/Co 3 O 4 nanomaterials using a simple MOF approach and exhibited sensor response to 300 ppb H 2 S at 40 °C, also Zhang et al 28 developed MOFs-derived hierarchical Co 3 O 4 structures for acetone at a working temperature of 190 °C.…”