Enhanced Gas-Sensing Performance of Fe-Doped Ordered Mesoporous NiO with Long-Range Periodicity

Abstract

This paper reports the effect of mesoporous morphology and metal doping on the gas-sensing behavior of ordered mesoporous nickel oxide (NiO) materials. NiO samples with varied porous periodicity have been successfully synthesized via an improved nanocasting method. TEM, SEM, SAXRD, XRD, and nitrogen physisorption techniques are used to prove the presence of different mesostructured periodicity, as well as crystallinity, particle size, and pore size distribution of the as-synthesized NiO. The gas-sensing characterization indicates that the ordered mesoporous NiO with a long-range mesoporous periodicity based gas sensor exhibits a better ethanol sensing property than that of the ordered mesoporous NiO with short-range mesoporous periodicity. This result is due to the large specific surface area with sufficient sensing active sites, appropriate pore size distribution for enough gas diffusion, and proper particle size for effective charge accumulation of ordered mesoporous NiO with long-range periodicity. Furthermore, metal element doping, including Fe and Co, is used to adjust the sensitivity of the ordered mesoporous NiO based sensor. By doping of the Fe element on the optimizing mesoporous NiO, the gas-sensing property was obviously improved. The reason for that is attributed to the mesoporous structure and surface chemical state changed by the doping of Fe, resulting in more gas adsorption, diffusion, and reaction and attaining the enhanced gas-sensing performance.

A two-step synthesis of nanosheet-covered fibers based on α-Fe2O3/NiO composites towards enhanced acetone sensing

“…In order to reflect the enhanced sensing performance of as-synthesized sensors, the results obtained in this study were quantitatively compared with those stated by many research groups about n-type α -Fe 2 O 3 and p-type NiO based sensors towards acetone, listed in Table 2 . The gas response of S-2 based α-Fe 2 O 3 /NiO nanosheet-covered fibers was the highest at low acetone concentration and relatively lower operating temperature of 169 °C, showing comparatively higher efficiency than those reported in the given literature 16 , 54 – 56 . Therefore, it is believed that novel S-2 based α -Fe 2 O 3 /NiO nanosheet-covered fibers prepared in this study provide great interest for the further analysis in the field of gas-sensing application.…”

“…Generally, the gas-sensitivity of p-type metal oxides was relatively lower than that of n-type metal oxides due to differences in their gas sensing mechanisms 10 – 12 . Presently, various effective approaches have been introduced to boost the gas-sensing features of the p-type or n-type metal oxides based sensors involving the assembly of complex and multidimensional nanostructures 13 , the materialization of nanocomposites 14 , the loading of noble metal catalysts 15 and the aliovalent ions doping 16 . P-type nickel oxide (NiO) with 3.4 eV energy gap and n-type hematite ( α -Fe 2 O 3 ) with 2.0 eV energy gap are dissimilar imperative functional materials existing as various morphological structures 17 – 20 , which have received general attention because of their unique physical and chemical features leading to their great performance in wide range of applications including dye-sensitized solar cells 21 , 22 , catalysis 23 , 24 , gas sensors 25 , 26 , electrodes 27 , 28 , magnetic materials 29 , 30 and electrochemical supercapacitors 31 , 32 etc .…”

Ordered mesoporous NiFe2O4 with ultrathin framework for low-ppb toluene sensing

“…Recently, ordered mesoporous metal oxides such as SnO 2 [24,25], In 2 O 3 [26][27][28][29], Cr 2 O 3 [30,31], NiO [32][33][34], Co 3 O 4 [35,36], ZnO [37,38], WO 3 [39][40][41], have widely been investigated as semiconducting gas-sensing materials since their large specific surface area and ordered porous structure allows for the improved sensing performance [42]. Nickel ferrite (NiFe 2 O 4 ) is one of the well-known spinel-type semiconductors and could find application in wide fields including gas sensor [43][44][45], catalysis [46][47][48], magnetism [49][50][51], and so on.…”

Urchin-like SnO2 nanoflowers via hydrothermal synthesis and their gas sensing properties

“…These 3D hierarchical nanostructures are assumed to be the most effective because of their porous nanostructures formed by the adjacent building blocks. On the other hand, gas sensing performances of SnO 2 can remarkably be improved once the size shrinks to a critical value of 14 nm (2 λD) [9,10]. This is confirmed by Yamazoe et al [11], claiming that the critical size of SnO 2 nanomaterials is 5-15 nm for the effective detection of H 2 and CO.…”