Hydrothermal Synthesis of Co3O4/ZnO Hybrid Nanoparticles for Triethylamine Detection

Abstract

Development of high performances gas sensors to monitor and detect the volatile organic compound triethylamine is of paramount importance for health and environmental protection. The Co3O4-ZnO nanoparticles composite was successfully synthesized by the one-step hydrothermal route and annealing process in this work. The gas sensitivity test results show that the composite exhibits excellent triethylamine-sensing performance at a cobalt content of 1 at%, indicating potential application for triethylamine detection. The sensor based on the Co3O4-ZnO composite had higher sensitivity to triethylamine, better selectivity, and faster response recovery rate compared with pure ZnO sensor. Combined with the structural characteristics of the characterized Co3O4-ZnO nanocomposite, the optimized triethylamine sensing performances can be ascribed to the p-n heterojunction effect between Co3O4 and ZnO, as well as the catalytic and high oxygen adsorption properties of Co3O4.

Hydrogen Gas Sensing Performances of p-Type Mn3O4 Nanosystems: The Role of Built-in Mn3O4/Ag and Mn3O4/SnO2 Junctions

“…Conversely, as concerns Mn3O4-SnO2, a maximum-like response behavior was observed, the best operating temperature being 200 °C. Such a response trend, in line with previous reports regarding H2 detection by other metal oxides [7,9,17,19,29,43,64], suggested the occurrence of a steady equilibrium between hydrogen adsorption and desorption at 200 °C, whereas an increase of the working temperature resulted in a predominant analyte desorption [27,33,55,64,65]. The lower value of the optimum operating temperature for Mn3O4-SnO2 in comparison to Mn3O4-Ag is in line with the more efficient SnO2 → Mn3O4 electron transfer (see the above XPS data).…”

“…For both Mn 3 O 4 -Ag and Mn 3 O 4 -SnO 2 systems, the higher content of oxygen defects at the composite surface with respect to bare Mn 3 O 4 (see the above XPS data and Figure S2), as well as the exposure of a high density of heterointerfaces, can in fact supply active sites for a more efficient chemisorption of both oxygen and analyte molecules, which, in turn, boosts the resulting gas responses [4,8,[16][17][18]30,43]. In addition, the intimate component contact enabled by the adopted preparation route, yielding a good intergranular coupling, enables a proficient exploitation of their chemical interplay [38,44,48], related to the synergistical combination of materials with different catalytic activities [10,27,37,41,47]. Hence, the improved sensing performances of functionalized Mn 3 O 4 systems can be related to the concomitance of electronic and catalytic effects.…”

“…Beyond sensitivity, selectivity is an important parameter for the eventual utilization of gas sensing devices [6,11,19,27,30]. The responses towards a specific test gas are in fact required to be higher than those of other potential interferents, in order to avoid false alarms in real-time gas monitoring equipment [36,38,39].…”

“…Simple architecture, cost-effective fabrication, stability under the operating conditions, and high efficiency, are the main requirements and core features of advanced sensors needed for such applications [16]. Among the various active systems and devices [20][21][22][23][24], metal oxide nanostructures have been the subject of an increasing interest, thanks to their high carrier mobility, easy fabrication and excellent stability [9,[25][26][27][28]. In particular, whereas n-type oxide semiconductors have been largely investigated as gas sensors [8,9,12,15], p-type ones have not yet been widely studied [4,17,29,30], since their responses are typically lower than those of n-type systems with comparable morphology [31][32][33].…”

Design and Synthesis of Novel 2D Porous Zinc Oxide-Nickel Oxide Composite Nanosheets for Detecting Ethanol Vapor

“…Similarity, the p-type Mn 3 O 4 /n-type SnO 2 heterogeneous system exhibits improved H 2 gas-sensing performance, superior to bare Mn 3 O 4 [ 28 ]. The gas sensor based on the Co 3 O 4 -ZnO p-n composite has higher sensitivity to triethylamine compared with pure ZnO sensor; the optimized triethylamine sensing performances can be ascribed to the p-n heterojunction effect between Co 3 O 4 and ZnO [ 29 ]. The PdO/ZnO p–n heterojunction in the PdO/ZnO composite nanostructures improves acetaldehyde gas-sensing performance of the pristine ZnO nanostructures [ 30 ].…”