“…These results provide evidence that the deposited thin TiO2 film protects the sensor, increasing its lifespan. Thus, the titania (TiO2) ultra-thin layers deposited on top of Cu2O/CuO using spray pyrolysis method can be used for long-term stabilization of functionalities of sensors to provide protection against corrosion at high temperatures [27][28][29][30]55,56 Cite this paper as : O. NATO Science for Peace and Security Programme (SPS) within the grant G5634 "Advanced Electro-Optical Chemical Sensors" AMOXES.…”
Highly sensitive TiO2/Cu2O/CuO multi-nanolayers have been grown in various thicknesses by a cost-effective and reproducible combined spray-sputtering-annealing approach. The ultra-thin TiO2 films were deposited by spray pyrolysis on top of sputtered-annealed Cu2O/CuO nanolayers to enhance their gas sensing performance and to improve their protection against corrosion at high operating temperatures. The prepared heterostructures have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet visible (UV-Vis) and microRaman spectroscopy. The gas sensing properties were measured at several operating temperatures, where the nanolayered sensors with oxide thicknesses of between 20 and 30 nm (Cu2O/CuO nanolayers) exhibited a high response and excellent selectivity to ethanol vapour only after thermal annealing at 420C. The results obtained at an operating temperature of 350 C demonstrate that the CuO/Cu2O nanolayers with a thickness between 20 and 30 nm are sensitive mainly to ethanol vapour, with a response of ~150. The response changes from ethanol vapors to hydrogen gas as CuO/Cu2O nanolayers thickness changes from 50 nm to 20 nm. Density functional theory-based calculations were carried out of the geometries of the CuO(1 ̅ 11)/Cu2O(111) and TiO2(111)/CuO(1 ̅ 11)/Cu2O(111) heterostructures and their sensing mechanism towards alcohols of different chain lengths and molecular hydrogen. The reconstructed hexagonal Cu2O(111) surface and the reconstructed monoclinic CuO(1 ̅ 11) and TiO2(111) facets, all terminated in an O layer, lead to the lowest surface energies for each isolated material. We studied the formation of the binary and ternary heteroepitaxial interfaces for the surface planes with the best matching lattices. Despite the impact of the Cu2O(111) substrate in lowering the atomic charges of the CuO(1 ̅ 11) adlayer in the binary sensor, we found that it is the different surface structures of the CuO(1 ̅ 11)/Cu2O(111) and TiO2(111)/CuO(1 ̅ 11)/Cu2O(111) devices that are fundamental in driving the change in the sensitivity response observed experimentally.
“…These results provide evidence that the deposited thin TiO2 film protects the sensor, increasing its lifespan. Thus, the titania (TiO2) ultra-thin layers deposited on top of Cu2O/CuO using spray pyrolysis method can be used for long-term stabilization of functionalities of sensors to provide protection against corrosion at high temperatures [27][28][29][30]55,56 Cite this paper as : O. NATO Science for Peace and Security Programme (SPS) within the grant G5634 "Advanced Electro-Optical Chemical Sensors" AMOXES.…”
Highly sensitive TiO2/Cu2O/CuO multi-nanolayers have been grown in various thicknesses by a cost-effective and reproducible combined spray-sputtering-annealing approach. The ultra-thin TiO2 films were deposited by spray pyrolysis on top of sputtered-annealed Cu2O/CuO nanolayers to enhance their gas sensing performance and to improve their protection against corrosion at high operating temperatures. The prepared heterostructures have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet visible (UV-Vis) and microRaman spectroscopy. The gas sensing properties were measured at several operating temperatures, where the nanolayered sensors with oxide thicknesses of between 20 and 30 nm (Cu2O/CuO nanolayers) exhibited a high response and excellent selectivity to ethanol vapour only after thermal annealing at 420C. The results obtained at an operating temperature of 350 C demonstrate that the CuO/Cu2O nanolayers with a thickness between 20 and 30 nm are sensitive mainly to ethanol vapour, with a response of ~150. The response changes from ethanol vapors to hydrogen gas as CuO/Cu2O nanolayers thickness changes from 50 nm to 20 nm. Density functional theory-based calculations were carried out of the geometries of the CuO(1 ̅ 11)/Cu2O(111) and TiO2(111)/CuO(1 ̅ 11)/Cu2O(111) heterostructures and their sensing mechanism towards alcohols of different chain lengths and molecular hydrogen. The reconstructed hexagonal Cu2O(111) surface and the reconstructed monoclinic CuO(1 ̅ 11) and TiO2(111) facets, all terminated in an O layer, lead to the lowest surface energies for each isolated material. We studied the formation of the binary and ternary heteroepitaxial interfaces for the surface planes with the best matching lattices. Despite the impact of the Cu2O(111) substrate in lowering the atomic charges of the CuO(1 ̅ 11) adlayer in the binary sensor, we found that it is the different surface structures of the CuO(1 ̅ 11)/Cu2O(111) and TiO2(111)/CuO(1 ̅ 11)/Cu2O(111) devices that are fundamental in driving the change in the sensitivity response observed experimentally.
“…The ZnO-rGO films possess photocatalytic activity and photoinduced superhydrophilicity, and increased content of rGO enhanced both photocatalytic activity and photoinduced superhydrophilicity of the ZnO-based films (Ref 112 ). For reduction of HAIS, Won et al prepared TiO 2 -based transparent coatings as one such potential self-cleaning surface for touch screen application and evaluated their antimicrobial efficacy under dark and illuminated conditions (Ref 113 ). It was revealed that n-Ag/TiO 2 (< 100 nm) coated samples achieved greater than 80% bactericidal efficacy with the lowest bacterial attachment after UV exposure (Ref 113 ).…”
“…For reduction of HAIS, Won et al prepared TiO 2 -based transparent coatings as one such potential self-cleaning surface for touch screen application and evaluated their antimicrobial efficacy under dark and illuminated conditions (Ref 113 ). It was revealed that n-Ag/TiO 2 (< 100 nm) coated samples achieved greater than 80% bactericidal efficacy with the lowest bacterial attachment after UV exposure (Ref 113 ).…”
There have been ever-growing demands for disinfection of water and air in recent years. Efficient, eco-friendly, and cost-effective methods of disinfection for pathogens are vital to the health of human beings. The photocatalysis route has attracted worldwide attention due to its highly efficient oxidative capabilities and sustainable recycling, which can be used to realize the disinfection purposes without secondary pollution. Though many studies have comprehensively reviewed the work about photocatalytic disinfection, including design and fabrication of photocatalytic coatings, inactivation mechanisms, or practical applications, systematic reviews about the disinfection photocatalysis coatings from fabrication to effort for practical use are still rare. Among different ways of fabricating photocatalytic materials, thermal spray is a versatile surface coating technique and competitive in constructing large-scale functional coatings, which is a most promising way for the future environmental purification, biomedical and life health applications. In this review, we briefly introduced various photocatalytic materials and corresponding inactivation mechanisms for virus, bacteria and fungus. We summarized the thermal-sprayed photocatalysts and their antimicrobial performances. Finally, we discussed the future perspectives of the photocatalytic disinfection coatings for potential applications. This review would shed light on the development and implementation of sustainable disinfection strategies that is applicable for extensive use for controlling pathogens in the near future.
“…3 C [ 27 , 83 ]. Such metal-TiO 2 composite systems based nanocoatings not only can provide better antimicrobial activity against microorganisms but also show promising self-cleaning/recyclable activities in presence of light (UV and visible) as well as in dark [ 40 , [85] , [86] , [87] , [88] ]. Fig.…”
Section: Tio
2
As Antimicrobial Photocatalystsmentioning
The whole world is struggling with current coronavirus pandemic that shows urgent need to develop novel technologies, medical innovations or innovative materials for controlling SARS-CoV-2 infection. The mode of infection of SARS-CoV-2 is still not well known and seems to spread through surface, air, and water. Therefore, the whole surrounding environment needs to be disinfected with continuous function. For that purpose, materials with excellent antiviral properties, cost effective, environmental friendly and practically applicable should be researched. Titanium dioxide (TiO
2
) under ultraviolet light produces strong oxidative effect and is utilized as photocatalytic disinfectant in biomedical field. TiO
2
based photocatalysts are effective antimicrobial/antiviral agents under ambient conditions with potential to be used even in indoor environment for inactivation of bacteria/viruses. Interestingly, recent studies highlight the effective disinfection of SARS-CoV-2 using TiO
2
photocatalysts. Here, scope of TiO
2
photocatalysts as emerging disinfectant against SARS-CoV-2 infection has been discussed in view of their excellent antibacterial and antiviral activities against various bacteria and viruses (e.g. H1N1, MNV, HSV, NDV, HCoV etc.). The current state of development of TiO
2
based nano-photocatalysts as disinfectant shows their potential to combat with SARS-CoV-2 viral infection and are promising for any other such variants or viruses, bacteria in future studies.
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