Controllable Defect Redistribution of ZnO Nanopyramids with Exposed {101̅1} Facets for Enhanced Gas Sensing Performance

Abstract

ZnO nanopyramids (NPys) with exposed crystal facets of {101̅1} were synthesized via a one-step solvothermal method, having a uniform size with a hexagonal edge length of ∼100 nm and a height of ∼200 nm. Technologies of XRD, TEM, HRTEM, Raman, PL, and XPS were used to characterize the morphological and structural properties of the products, while the corresponding gas sensing properties were determined by using ethanol as the target gas. For the overall goal of defect engineering, the effect of aging temperature on the gas sensing performance of the ZnO NPys was studied. The test results showed that, at the aging temperature of 300 °C, the gas sensing property has been improved to the best, with the fast response-recovery time and the excellent selectivity, because the ZnO300 has the most electron donors for absorbing the largest content of O(2-). Model of defect redistribution was used to explicate the changing of the surface defects at different aging temperatures. The findings showed that, in addition to VO, Zni was the dominant defect of the {101̅1} crystal facet. The gas sensing performance of the ZnO NPys was determined by the contents of VO and Zni, with all of the defects redistributed on the surface. All of the results will be noticeable for the improvement of the sensing performance of materials with special crystal facet exposing.

Strong metal–support interaction in novel core–shell Au–CeO2nanostructures induced by different pretreatment atmospheres and its influence on CO oxidation

“…The OI belongs to lattice oxygen, OII is associated with the O 2− ions in the oxygen deficient regions and OIII is attributed to absorbed oxygen, respectively. [7][8][9][10] In Table S4, the relative amount OII for H-CeO 2 -H 2 is higher than that for the H-CeO 2 -O 2 , that is, the ruductive atmosphere facilitate the formation of oxygen vacancy.…”

ZnO nanorods/graphene oxide sheets prepared by chemical bath deposition for volatile organic compounds detection

“…The relationship between the gas concentration (C g ) and the gas response (S g ) can be written according to the gas absorption model of semiconductors as follows (Eq. (1)) [47,48]:…”

“…When the temperature is increased to 450 C, to induce a stronger activation, more atomic oxygens are extracted from the surface, and consequently, more oxygen vacancies ðV X O Þ are generated [47]. Therefore, reducing molecules as acetone react with the O 2À species present on the nanorods surface resulting in CO 2 , H 2 O, and more electrons.…”

Ultrasensitive and low detection limit of acetone gas sensor based on W-doped NiO hierarchical nanostructure

“…Among them, the response of the sensor based on the 4.0 at% W-doped NiO was apparently higher than those of the undoped, 2.0 at%, and 6.0 at% W-doped NiO to different acetone concentration we tested. Furthermore, according to the gas absorption model of semiconductors, the gas response (S g ) relation to target gas concentration (C g ) can be empirically represented by [44,45] S g = a C g β + 1 (1) where a is a prefactor, and β is the response order. The value of β is usually 1 for the adsorbed surface oxygen ion of O -or 1/2 for O 2-, depending on the charge state of the surface species, the stoichiometry of the elementary surface reactions, and the microstructure of the sensing material.…”