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

Lithium-ion batteries (LIBs) still need continuous safety monitoring based on their intrinsic properties, as well as due to the increase in their sizes and device requirements. The main causes of fires and explosions in LIBs are heat leakage and the presence of highly inflammable components. Therefore, it is necessary to improve the safety of the batteries by preventing the generation of these gases and/or their early detection with sensors. The improvement of such safety sensors requires new approaches in their manufacturing. There is a growing role for research of nanostructured sensor’s durability in the field of ionizing radiation that also can induce structural changes in the LIB’s component materials, thus contributing to the elucidation of fundamental physicochemical processes; catalytic reactions or inhibitions of the chemical reactions on which the work of the sensors is based. A current method widely used in various fields, Direct Ink Writing (DIW), has been used to manufacture heterostructures of Al2O3/CuO and CuO:Fe2O3, followed by an additional ALD and thermal annealing step. The detection properties of these 3D-DIW printed heterostructures showed responses to 1,3-dioxolan (DOL), 1,2-dimethoxyethane (DME) vapors, as well as to typically used LIB electrolytes containing LiTFSI and LiNO3 salts in a mixture of DOL:DME, as well also to LiPF6 salts in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) at operating temperatures of 200 °C–350 °C with relatively high responses. The combination of the possibility to detect electrolyte vapors used in LIBs and size control by the 3D-DIW printing method makes these heterostructures extremely attractive in controlling the safety of batteries

ENHANCEMENT IN UV SENSING PROPERTIES OF Zno:Ag NANOSTRUCTURED FILMS BY SURFACE FUNCTIONALIZATION WITH NOBLE METALIC AND BIMETALLIC NANOPARTICLES

In this study, Ag-doped ZnO (ZnO:Ag) nanostructured films were functionalized with silver nanoparticles (Ag NPs), silver-platinum bimetallic nanoparticles (AgPt NPs) and silver-gold bimetallic NPs (AgAu NPs) using a gas phase PVD process based on a Haberland type gas aggregation cluster source and unipolar DC planar magnetron sputtering. Ultraviolet (UV) sensing investigations showed arespectable time constants reduction for rising and decaying photocurrents, as well as an increase for the UV response. Compared to a pristine nanostructured film the surface functionalization with Ag, AgPt and AgAu increased the UV response by factors of 2.7, 3.5 and 4, respectively. The increased performances of the here presented ZnO:Ag nanostructured films functionalized with monometallic and bimetallic NPs based photodetectors are explained by the increased lifetime of photogenerated electron –hole pairs, as well as the formation of nanoscale Schottky barriers at the interface of Au/ZnO:Ag and Pt/ZnO:Ag

Room temperature gas nanosensors based on individual and multiple networked Au-modified ZnO nanowires

International audienc

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Heterojunctions are used in solar cells and optoelectronics applications owing to their excellent electrical and structural properties. Recently, these energy-efficient systems have also been employed as sensors to distinguish between individual gases within mixtures. Through a simple and versatile functionalization approach using noble metal nanoparticles, the sensing properties of heterojunctions can be controlled at the nanoscopic scale. This work reports the nanoparticle surface functionalization of TiO2/CuO/Cu2O mixed oxide heterostructures, where the gas sensing selectivity of the material is tuned to achieve versatile sensors with ultra-low power consumption. Functionalization with Ag or AgPt-nanoclusters (5–15 nm diameter), changed the selectivity from ethanol to butanol vapour, whereas Pd-nanocluster functionalization shifts the selectivity from the alcohols to hydrogen. The fabricated sensors show excellent low power consumption below 1 nW. To gain insight into the selectivity mechanism, density functional theory (DFT) calculations have been carried out to simulate the adsorption of H2, C2H5OH and n-C4H9OH at the noble metal nanoparticle decorated ternary heterostructure interface. These calculations also show a decrease in the work function by ~2.6 eV with respect to the pristine ternary heterojunctions. This work lays the foundation for the production of a highly versatile array of sensors of ultra-low power consumption with applications for the detection of individual gases in a mixture

Surface functionalization of ZnO:Ag columnar thin films with AgAu and AgPt bimetallic alloy nanoparticles as an efficient pathway for highly sensitive gas discrimination and early hazard detection in batteries

For a fast and reliable monitoring of hazardous environments, the discrimination and detection of volatile organic compounds (VOCs) in the low ppm range is critically important, which requires the development of new chemical sensors. We report herein, a novel approach to tailor the selectivity of nanocomposite thin film sensors by investigating systematically the effect of surface decoration of Ag-doped ZnO (ZnO:Ag) columnar thin films. We have used AgPt and AgAu noble bimetallic alloy nanoparticles (NPs) to decorate the surfaces of ZnO:Ag and we have measured their resulting gas sensing properties towards VOC vapors and hydrogen gas. The gas response of the nanocomposite containing AgAu NPs to 100 ppm of ethanol, acetone, n-butanol, 2-propanol and methanol vapors was increased on average by a factor of 4 compared to the pristine ZnO:Ag columnar films. However, decoration with AgPt NPs led to a considerable reduction of the gas response to all VOC vapors and an increase of the response to H2 gas by roughly one order of magnitude, indicating a possible route to tailor the selectivity by surface decoration. As such, the reported NP-decorated ZnO:Ag thin film sensors should be suitable for the detection of H2 in Li-ion batteries, which is an early indication of the thermal runaway that leads to complete battery failure and possible explosion. To understand the impact of NP surface decoration on the gas sensing properties of ZnO:Ag thin films, we have employed density functional theory calculations with on-site Coulomb corrections and long-range dispersion interactions (DFT+U–D3-(BJ)) to investigate the adsorption of various VOC molecules and hydrogen onto the Ag-doped and NP-decorated (10[1 with combining macron]0) surface of zinc oxide ZnO. The calculated surface free energies indicate that Ag5Au5/ZnO(10[1 with combining macron]0):Ag is the most favourable system for the detection of VOCs, which based on its work function is also the most reactive towards these species. Our calculated adsorption energies show that Ag9Pt/ZnO(10[1 with combining macron]0):Ag has the largest preference for H2 gas and the lowest preference for the organic adsorbates, which is in line with the high selectivity of AgPt/ZnO:Ag sensors towards the hydrogen molecule observed in our experiments

Effect of noble metal functionalization and film thickness on sensing properties of sprayed TiO2 ultra-thin films

International audienc

Tailoring the selectivity of ultralow-power heterojunction gas sensors by noble metal nanoparticle functionalization

Heterojunctions are used in solar cells and optoelectronics applications owing to their excellent electrical and structural properties. Recently, these energy-efficient systems have also been employed as sensors to distinguish between individual gases within mixtures. Through a simple and versatile functionalization approach using noble metal nanoparticles, the sensing properties of heterojunctions can be controlled at the nanoscopic scale. This work reports the nanoparticle surface functionalization of TiO2/CuO/Cu2O mixed oxide heterostructures, where the gas sensing selectivity of the material is tuned to achieve versatile sensors with ultra-low power consumption. Functionalization with Ag or AgPt-nanoclusters (5–15 nm diameter), changed the selectivity from ethanol to butanol vapour, whereas Pd-nanocluster functionalization shifts the selectivity from the alcohols to hydrogen. The fabricated sensors show excellent low power consumption below 1 nW. To gain insight into the selectivity mechanism, density functional theory (DFT) calculations have been carried out to simulate the adsorption of H2, C2H5OH and n-C4H9OH at the noble metal nanoparticle decorated ternary heterostructure interface. These calculations also show a decrease in the work function by ~2.6 eV with respect to the pristine ternary heterojunctions. This work lays the foundation for the production of a highly versatile array of sensors of ultra-low power consumption with applications for the detection of individual gases in a mixture