Single CuO/Cu₂O/Cu Microwire Covered by a Nanowire Network as a Gas Sensor for the Detection of Battery Hazards

Abstract

In this study, a strategy to prepare CuO/Cu2O/Cu microwires that are fully covered by a nanowire (NW) network using a simple thermal-oxidation process is developed. The CuO/Cu2O/Cu microwires are fixed on Au/Cr pads with Cu microparticles. After thermal annealing at 425 °C, these CuO/Cu2O/Cu microwires are used as room-temperature 2-propanol sensors. These sensors show different dominating gas responses with operating temperatures, e.g., higher sensitivity to ethanol at 175 °C, higher sensitivity to 2-propanol at room temperature and 225 °C, and higher sensitivity to hydrogen gas at ∼300 °C. In this context, we propose the sensing mechanism of this three-in-one sensor based on CuO/Cu2O/Cu. X-ray diffraction (XRD) studies reveal that the annealing time during oxidation affects the chemical appearance of the sensor, while the intensity of reflections proves that for samples oxidized at 425 °C for 1 h the dominating phase is Cu2O, whereas upon further increasing the annealing duration up to 5 h, the CuO phase becomes dominant. The crystal structures of the Cu2O–shell/Cu–core and the CuO NW networks on the surface were confirmed with a transmission electron microscope (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED), where (HR)­TEM micrographs reveal the monoclinic CuO phase. Density functional theory (DFT) calculations bring valuable inputs to the interactions of the different gas molecules with the most stable top surface of CuO, revealing strong binding, electronic band-gap changes, and charge transfer due to the gas molecule interactions with the top surface. This research shows the importance of the nonplanar CuO/Cu2O layered heterostructure as a bright nanomaterial for the detection of various gases, controlled by the working temperature, and the insight presented here will be of significant value in the fabrication of new p-type sensing devices through simple nanotechnology.

Oriented Catalytic Oxidation Induced Fabrication of CuO/Mn3O4 Hierarchical Arrays as Binder‐Free Electrodes for High‐Performance Supercapacitor

“…[42] Moreover, compared with that of CuO/Mn 3 O 4 nanorod precursors (Figure S1a, Supporting Information), no characteristic peaks of Cu(OH) 2 could be observed any more due to the complete decomposition of the residual Cu(OH) 2 in CuO/Mn 3 O 4 nanorods under annealing procedure, but new diffraction peaks centered at 36.4°, 42.3°, and 61.3° are clearly identified, which could be separately assigned to (111), (200), and (220) planes of the newly formed cubic Cu 2 O (PDF No. 05-0667), [44] in good agreement with the HRTEM results. Unfortunately, no obvious peaks indexed to Mn 3 O 4 could be directly identified here owing to its too low percentage (atomic ratio of Mn in the nanorods is only 1.06%).…”

Additive Manufacturing as a Means of Gas Sensor Development for Battery Health Monitoring

“…The gas-sensing properties measurements were performed continuously through a Keithley2400 source meter using LabView software (from National Instruments), as described in previous works [34,35]. The gas and vapor responses were calculated according to Equation (1), where R gas and R air represent the electrical resistances of the samples exposed to gas/vapors and under normal environmental conditions, respectively [36,37]:…”

Humidity‐Initiated Gas Sensors for Volatile Organic Compounds Sensing

“…On the other hand, smaller‐sized VOCs sensors technologies, including metal oxide semiconductor (MOS) sensors, are typically designed to detect a precise molecule or class of molecules. [ 18–21 ] The significant time and cost to customize to a particular application decrease tunability. In addition, MOS sensors have low humidity resilience [ 19,21 ] and so, are not well‐suited to detection tasks in uncontrolled outdoor field environments that are often at high humidity.…”

“…[ 18–21 ] The significant time and cost to customize to a particular application decrease tunability. In addition, MOS sensors have low humidity resilience [ 19,21 ] and so, are not well‐suited to detection tasks in uncontrolled outdoor field environments that are often at high humidity. Herein, we conceive of and demonstrate a new gas sensing concept that we believe addresses all requirements for remote field detection of VOCs and so, may be enabling for many applications including HLB diagnosis.…”