Abstract: A surface-enhanced Raman scattering (SERS)-active electrode include a solid support; a porous oxide layer containing transition metal oxide nanoparticles present on a surface of the solid support and has a mean pore size of 2 to 30 nm; and at least one of noble metal nanoneedles and noble metal nanorings present on the porous oxide layer. The noble metal nanoneedles have an average length of 350-800 nm, a flat end with an average width in a range of 100-150 nm, and a pointed end. The noble metal nanorings have a thickness of 50-300 nm and are present in the form of annular clusters having various elliptical shapes with an average diameter in a range of 35-60 nm.

Abstract: A hydrogen gas sensor is provided. The hydrogen gas sensor includes a polycarbonate substrate having hydrophobic nanostructures. The hydrogen gas sensor further includes a palladium layer in the form of nanoscale petals on the hydrophobic nanostructure. A method of making the hydrogen gas sensor is also provided. The method of making the hydrogen gas sensor includes fabricating the polycarbonate substrate. The method of making the hydrogen gas sensor further includes coating the polycarbonate substrate with the palladium layer. A method of using the hydrogen gas sensor is also provided. The method of using the hydrogen gas sensor includes contacting a palladium coated hydrophobic nanostructure of the hydrogen gas sensor with a gas sample comprising hydrogen gas.

Abstract: A gas sensor is provided. The gas sensor comprises a substrate and an active material, comprising first noble metal nanoparticles, a zinc oxide layer, and second noble metal nanoparticles. These components are arranged such that the zinc oxide layer prevents contact between the second noble metal nanoparticles and the first noble metal nanoparticles and between the second noble metal nanoparticles and the substrate. A method of forming the gas sensor is also provided. The method involves sputtering a first film of a first noble metal onto the substrate, annealing to form the first noble metal nanoparticles, depositing the zinc oxide layer, sputtering a second film of a second noble metal, and annealing to form the gas sensor. The gas sensor is used in a method of detecting the presence of a ketone in a gas sample.

Abstract: A surface-enhanced Raman scattering (SERS) substrate and its method of formation is disclosed. The surface-enhanced Raman scattering (SERS) substrate comprises a solid support, a first noble metal nanoparticles is disposed on the solid support, a porous oxide layer comprising transition metal oxide nanoparticles is disposed on the first noble metal nanoparticles and a second noble metal nanoparticles is disposed on the porous oxide layer. The porous oxide layer prevents contact between the first noble metal nanoparticles and the second noble metal nanoparticles and has a mean pore size of 2 to 30 nm.

Abstract: A surface-enhanced Raman scattering (SERS) substrate and its method of formation is disclosed. The surface-enhanced Raman scattering (SERS) substrate comprises a solid support, a first noble metal nanoparticles is disposed on the solid support, a porous oxide layer comprising transition metal oxide nanoparticles is disposed on the first noble metal nanoparticles and a second noble metal nanoparticles is disposed on the porous oxide layer. The porous oxide layer prevents contact between the first noble metal nanoparticles and the second noble metal nanoparticles and has a mean pore size of 2 to 30 nm.

Abstract: A hydrogen sensor that efficiently detects hydrogen gas at room temperature comprising a gold decorated reduced graphene oxide/zinc oxide (Au/rGO/ZnO) heterostructured composite, methods for making this sensor and a method for sensitive room temperature detection of hydrogen using the sensor.

Abstract: A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O2? ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.

Abstract: A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O2? ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.

Abstract: A surface-enhanced Raman scattering (SERS) substrate and its method of formation is disclosed. The surface-enhanced Raman scattering (SERS) substrate comprises a solid support, a first noble metal nanoparticles is disposed on the solid support, a porous oxide layer comprising transition metal oxide nanoparticles is disposed on the first noble metal nanoparticles and a second noble metal nanoparticles is disposed on the porous oxide layer. The porous oxide layer prevents contact between the first noble metal nanoparticles and the second noble metal nanoparticles and has a mean pore size of 2 to 30 nm.

Abstract: A room temperature nitrogen dioxide gas sensor comprising tin(IV) oxide decorated with gold nanoparticles is described. The tin(IV) oxide may have an average layer thickness of 10-1,000 nm, and is topped with dispersed gold nanoparticles having an average longest dimension of 200-650 nm. The room temperature nitrogen dioxide gas sensor may be used to detect and measure levels of nitrogen dioxide gas at room temperature and at concentrations of 100 ppb-1800 ppm, with a high stability. A method of making the room temperature nitrogen dioxide sensor is also described, and involves sputtering to deposit a tin(IV) oxide layer and a gold layer on a substrate, followed by annealing.

Abstract: A hydrogen sensor that efficiently detects hydrogen gas at room temperature comprising a gold decorated reduced graphene oxide/zinc oxide (Au/rGO/ZnO) heterostructured composite, methods for making this sensor and a method for sensitive room temperature detection of hydrogen using the sensor.

Abstract: A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O2? ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.

Abstract: A room temperature nitrogen dioxide gas sensor comprising tin(IV) oxide decorated with gold nanoparticles is described. The tin(IV) oxide may have an average layer thickness of 10-1,000 nm, and is topped with dispersed gold nanoparticles having an average longest dimension of 200-650 nm. The room temperature nitrogen dioxide gas sensor may be used to detect and measure levels of nitrogen dioxide gas at room temperature and at concentrations of 100 ppb-1800 ppm, with a high stability. A method of making the room temperature nitrogen dioxide sensor is also described, and involves sputtering to deposit a tin(IV) oxide layer and a gold layer on a substrate, followed by annealing.

Abstract: A room temperature hydrogen gas sensor comprising tin(IV) oxide and platinum layered on an electrode substrate is described. The tin(IV) oxide may be polycrystalline with an average layer thickness of 10-700 nm, and topped with platinum having an average layer thickness of 1-15 nm. The room temperature hydrogen gas sensor may be used to detect and measure levels of H2 gas at room temperature and at concentrations of 50-1800 ppm, with fast response and high stability. A method of making the room temperature hydrogen gas sensor is also described, and involves sputtering to deposit tin(IV) oxide and platinum on a substrate, which is then subjected to low-temperature annealing step.

Abstract: A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O2? ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.

Abstract: A method of preparing silver nanoparticles, including silver nanorings. A zinc oxide thin film is formed initially by direct-current sputtering of a zinc target onto a substrate. A silver thin film is then formed by a similar sputtering technique, of a silver target onto the zinc oxide thin film. After that, the silver thin film is subject to an annealing treatment. The temperature, duration and atmosphere of the annealing treatment can be varied to control the average particle size, average distance between particles (density), particle size distribution of the silver nanoparticles. In at least one embodiment, silver nanoparticles of ring structure are produced.

Abstract: A method of preparing silver nanoparticles, including silver nanorings. A zinc oxide thin film is formed initially by direct-current sputtering of a zinc target onto a substrate. A silver thin film is then formed by a similar sputtering technique, of a silver target onto the zinc oxide thin film. After that, the silver thin film is subject to an annealing treatment. The temperature, duration and atmosphere of the annealing treatment can be varied to control the average particle size, average distance between particles (density), particle size distribution of the silver nanoparticles. In at least one embodiment, silver nanoparticles of ring structure are produced.

Abstract: A method of preparing silver nanoparticles, including silver nanorings. A zinc oxide thin film is formed initially by direct-current sputtering of a zinc target onto a substrate. A silver thin film is then formed by a similar sputtering technique, of a silver target onto the zinc oxide thin film. After that, the silver thin film is subject to an annealing treatment. The temperature, duration and atmosphere of the annealing treatment can be varied to control the average particle size, average distance between particles (density), particle size distribution of the silver nanoparticles. In at least one embodiment, silver nanoparticles of ring structure are produced.

Abstract: A method of preparing silver nanoparticles, including silver nanorings. A zinc oxide thin film is formed initially by direct-current sputtering of a zinc target onto a substrate. A silver thin film is then formed by a similar sputtering technique, of a silver target onto the zinc oxide thin film. After that, the silver thin film is subject to an annealing treatment. The temperature, duration and atmosphere of the annealing treatment can be varied to control the average particle size, average distance between particles (density), particle size distribution of the silver nanoparticles. In at least one embodiment, silver nanoparticles of ring structure are produced.