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In this study, a novel high length-diameter ratio NiO nanorods decorated with uniformly ZnO nanoparticles was synthesized via a facile one-step hydrothermal process. • A novel NiO nanorods decorated with uniformly ZnO nanoparticles was synthesized. • The NiO/ZnO composites based sensor show excellent ethanol gas response. • The p-n heterojunction and astonishing synergistic played an essential role in tgas-sensing performance. In this study, a novel high length-diameter ratio NiO nanorods decorated with uniform ZnO nanoparticles was synthesized via a facile one-step hydrothermal process. It was a surprise to find that the NiO/ZnO nanorods heterostructure based sensor demonstrated much more excellent ethanol gas sensing properties than that of undoped NiO nanorods. This enhancement of sensing properties may be attributed to their synergetic effect as well as the heterojunction at interface between the NiO nanorods and ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

In this work, WO 3 ·H 2 O nanorods and spherical network were successfully synthesized via a simple hydrothermal process and the gas sensing performance of the samples was investigated. The spherical network shows superior performance due to its porous structure and efficient electronic transmission on the network. • A novel spherical WO 3 ·H 2 O network was successfully prepared. • The spherical WO 3 ·H 2 O network exhibits an enhanced gas sensing performance compared to uniformly dispersed nanorods. • The porous structure as well as efficient electronic transmission play an important role in gas sensing process. A novel 3D spherical WO 3 ·H 2 O network assembled by numerous partially connected nanorods was successfully synthesized by a facile hydrothermal method. The ethanol sensing characteristics of two samples were investigated systematically and the results indicated that the spherical WO 3 ·H 2 O network exhibited an enhanced gas sensing performance due to its large specific surface area. In addition, the porous structure provides abundant channels for gas diffusion and the connected nanorods facilitate the transfer of electrons along the network, resulting in the improvement of gas sensing properties. [ABSTRACT FROM AUTHOR]

Unique nanosheet-assembled Ce-doped NiO hierarchical microflowers, whose nanosheet is comprised of a large amount of nanowires, was successfully synthesized via a hydrothermal route. The sensor based on the Ce-doped NiO microflowers exhibited a superior gas response towards ethanol than that of the pure sample. The novel hierarchical nature as well as the incorporation of Ce into NiO played an essential role in the sensing reaction. • Novel hierarchical Ce-doped NiO microflowers were synthesized hydrothermally. • The Ce-doped NiO based sensor exhibited enhanced ethanol gas response. • The unique hierarchical nature and incorporation of Ce into NiO played a vital role in sensing reaction. In this work, novel flower-like Ce-doped NiO hierarchical architectures were successfully prepared through a facile one-step hydrothermal route. Morphological and structural observations demonstrate that such microflower is assembled by a large amount of nanosheets, and the nanosheets is comprised of numerous nanowires which are randomly interwoven to each other. In comparison to the pure sample, the Ce-doped NiO microflowers exhibit superior ethanol sensing properties. The higher sensor response is primarily responsible for the unique hierarchical nanostructure and the change in effective hole concentration due to the incorporation of Ce into NiO. [ABSTRACT FROM AUTHOR]

Novel loosely and tightly arranged nanosheet-assembled flower-like WO 3 nanostructures were controllably synthesized under hydrothermal conditions. Through gas-sensing experiments towards NH 3 , it was found that the loosely-arranged WO 3 nanostructures exhibited a higher NH 3 response. This difference was due to the sparse cross-arrangement of the nanosheets on the surface of the sample and the larger specific surface area of the loosely-arranged structure. • Novel loosely and tightly arranged nanosheet-assembled flower-like WO 3 were synthesized. • The loosely-arranged WO 3 nanostructures exhibited the superior NH 3 sensing performance. • The factors affecting NH 3 -sensing properties are discussed in detail. Novel loosely and tightly arranged nanosheet-assembled flower-like WO 3 nanostructures were controllably synthesized via a facile hydrothermal approach. Additionally, NH 3 -sensing measurements were performed based on both samples. Remarkably, the loosely-arranged WO 3 nanostructures, which possess an abundance of semi-closed spaces and a larger specific surface area, exhibited improved NH 3 -sensing properties compared to that of the tightly-arranged WO 3 nanostructures. This discovery can provide guidance for improving the gas-sensing properties of nanosheet-assembled hierarchical MO x flower-like nanostructures. [ABSTRACT FROM AUTHOR]

A nest-like TiO 2 structure with remarkable gas sensitivity toward ethanol. • A Multilayer nest-like TiO 2 nanostructure has been synthesized by simple hydrothermal method. • The gas sensor based on the nest-like TiO 2 shows excellent response to ethanol. • The plausible mechanism involved in enhancing the gas sensing performances was discussed. A multilayer nest-like TiO 2 nanostructure assembled from one-dimensional nanowires has been synthesized by a simple hydrothermal method. This special structure not only has the characteristics of a network structure with many nanojunctions but also has high efficiency of gas transmission. We have revealed its remarkable gas sensitive property toward ethanol through a comparative study with unmodified nanowires. It is believed that its excellent gas sensing is due to its special nest-like structure providing a large number of chemical reaction chambers and sufficient gas transmission channels. [ABSTRACT FROM AUTHOR]

Graphical abstract In the study, a facile, inexpensive solution approach was utilized to prepare novel 3D porous Cu 2 O-MoS 2 microspheres, which were employed for NH 3 gas detection. The results indicated the sensor fabricated by the porous Cu 2 O-MoS 2 microspheres exhibited fascinating gas-sensing properties to NH 3 with high gas response and short response time. Remarkably, the unique architecture and p-n heterojunction design and build play a vital role in the gas sensing properties improvement. Highlights • Novel 3D porous Cu 2 O-MoS 2 microspheres were synthesized via a facile solution route. • The Cu 2 O-MoS 2 microspheres based sensor exhibited excellent gas sensing performances. • The mechanism enhanced sensing properties was discussed in detail. Abstract A facile, inexpensive solution approach was utilized to prepare novel 3D porous Cu 2 O-MoS 2 microspheres, which were employed for NH 3 gas detection. Morphological characterizations indicated porous MoS 2 microspheres were decorated with numerous Cu 2 O nanoparticles. The fabricated gas sensor based on the Cu 2 O-MoS 2 microspheres possessed high gas response of 43 with fast response and recovery speed towards NH 3 , good reproducibility as well as satisfactory stability, which were mainly ascribed to the distinctive 3D porous microsphere architecture and the formation of p-n heterojunction at the interface between the n-type MoS 2 and p-type Cu 2 O. [ABSTRACT FROM AUTHOR]

In this work, a novel two-dimensional seawave-like hierarchical WO 3 nanocomposite was synthesized by a one-step hydrothermal route. • Novel seawave-like hierarchical WO 3 nanocomposite was synthesized. • The sensor fabricated by seawave-like h-WO 3 nanostructure exhibited ultra-sensitivity to NH 3. • The mechanism enhanced gas sensing properties was discussed in detail. In this work, a novel two-dimensional seawave-like hierarchical WO 3 nanocomposite was synthesized by a one-step hydrothermal route. It was amazing that this novel two-dimensional WO 3 nanostructure was composed of one-dimensional worm-like WO 3 nanowires. Furthermore, a ultra-sensitivity towards ammonia was shown primarily attributed to abundant gas diffusion channels and large gas-sensitive reaction surface area furnished by one-dimensional worm-like WO 3 nanowires. Meanwhile, as the building units, the worm-like nanowires promote the directional transmission of electrons, resulting in an improvement of WO 3 gas sensing characteristics. [ABSTRACT FROM AUTHOR]

In this work, ZnCo 2 O 4 microrods with nanosheets on the surface were successfully synthesized on nickel foam by a simple hydrothermal process and its catalytic properties towards glucose were investigated. The results show that the as-prepared sample exhibits superior performance, which is attributed to the direct growth of active material on the substrate and the synergetic effect of zinc and cobalt. • ZnCo 2 O 4 microrods with nanosheets on the surface were successfully synthesized. • The ZnCo 2 O 4 microrods/Ni foam electrode was used to fabricate non-enzyme glucose sensor. • The as-prepared electrode exhibits excellent catalytic performance towards glucose. In this paper, ZnCo 2 O 4 microrods with nanosheets on the surface were successfully synthesized on nickel foam (NF) via a two-step process including hydrothermal reaction and subsequent calcination. The as-prepared sample was used to fabricate non-enzymatic glucose sensor which was proven to have excellent catalytic performance toward glucose in alkaline medium, such as high sensitivity (16.60 mA mM−1 cm−2), low detection limit (0.15 μM, S/N = 3) and excellent selectivity. These results suggest that ZnCo 2 O 4 microrods wrapped on nickel foam are promising electrode material for non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

The unique flower-like NiO/ZnO composite with porous nanosheets was triumphantly manufactured via the one-step hydrothermal method initially. It was considered that the construction of P-N junctions at the interface as well as the sheet-like porous microflowers architecture greatly contribute to the fantastic gas sensing properties of the prepared materials. Furthermore, a possible formation mechanism was proposed. • Nanosheet-assembled porous NiO/ZnO microflowers were fabricated hydrothermally. • The NiO/ZnO composites based sensor presented superior ethanol gas response. • The sheet-like porous microflowers architecture and P-N junctions greatly contributed to gas sensing. The unique flower-like NiO/ZnO composite with porous nanosheets has been triumphantly manufactured via the one-step hydrothermal method initially. On the basis of morphology observations and ethanol gas measurements, it is considered that the construction of P-N junctions at the interface as well as the sheet-like porous microflowers architecture greatly contribute to the fantastic gas sensing properties of the prepared materials, which exhibit superb gas response value and outstanding repeatability. Furthermore, a possible formation mechanism is proposed, elucidating the process of the oriented-attachment, the self-assembly in addition to the pores-development. [ABSTRACT FROM AUTHOR]

In this work, we have triumphantly synthesized porous NiCo 2 O 4 nanowires array on nickel foam (NiCo 2 O 4 NWs/NF) via a facile hydrothermal method. The sensitivity could reach up to 5916 μA mM−1 cm−2, meanwhile, the linear range was 1 μM–3.987 mM with a low detection limit of 0.94 μM (S/N = 3). Furthermore, it displayed good selectivity. • The porous NiCo 2 O 4 nanowires were constructed on nickel foam. • The sensor showed the highest sensitivity of 5916 μA mM−1 cm−2 in a wide linear range of 0.001–3.987 mM. • The structure offers abundant transport pathways and active sites to boost the electrochemical activity. In this work, we have triumphantly synthesized porous NiCo 2 O 4 nanowires array on nickel foam (NiCo 2 O 4 NWs/NF) via a facile hydrothermal method. Benefiting from its great one-dimensional porous nanowires architecture along with synergistic interactions between NiCo 2 O 4 arrays and Ni foam, the NiCo 2 O 4 NWs/NF-based sensor exhibited enhanced glucose sensing performance. The sensitivity could reach up to 5916 μA mM−1 cm−2, meanwhile, the linear range was 1 μM–3.987 mM with a low detection limit (LOD) of 0.94 μM (S/N = 3). Furthermore, it displayed good selectivity. These results inspire that the porous NiCo 2 O 4 nanowires will be a promising candidate for non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Graphical abstract A novel porous NiO nanosheet was synthesized by a one-step hydrothermal route and the gas sensor based on the porous nanosheet exhibits excellent gas response to hydrogen. We proposed a plausible mechanism of the sensing process and found that the porous structure improved the gas sensing performance with abundant gas channels and larger surface areas. Highlights • A novel porous NiO nanosheet was synthesized by a one-step hydrothermal route. • The gas sensor based on the porous nanosheet shows excellent response to hydrogen. • The plausible mechanism involved in enhancing the gas sensing performances was discussed. Abstract In this work, we reported the successful synthesis of a novel two-dimensional porous NiO nanosheet via a one-step hydrothermal route and subsequent calcination. It was surprise found that such NiO nanosheet exhibits a superior gas response towards H 2. The enhanced sensing ability may be benefited from the porous nanostructure, resulting in more sufficient pathways for gas diffusion and larger surface for chemical reaction. We hoped our findings could be in favor of further investigations on the fabrication of perfect two dimensional architectures. [ABSTRACT FROM AUTHOR]

• The hierarchical WO 3 /NiO porous microsphere and rough microsphere were synthesized via hydrothermal process. • The gas sensor based on the porous microsphere shows more excellent performances to ethanol. • The possible mechanism involved in enhancing the gas sensing performances was discussed in detail. Two novel hierarchical WO 3 /NiO microspheres with porous and rough surface have been prepared through a simple one-stop hydrothermal method. Interestingly, it is a surprise that the introduction of different amounts of WO 3 plays a critical role in the growth and self-assembly of nanosheets and then the morphology of microsphere. Further gas sensing experiment demonstrates that the sensor based on porous microsphere possesses prominent performance towards 100 ppm ethanol at the optimal working temperature of 300 °C compared with that of rough microsphere. It is believed that the enhanced gas sensing properties benefit from the porous structure on the surface with abundant active sites and gas passages for sufficient gas adsorption and diffusion. [ABSTRACT FROM AUTHOR]

The two-dimensional (2D) honeycomb-like nanoplates assembled by nanosheet arrays were synthesized using one-step hydrothermal method and the growth mechanism of this nanostructure was proposed. The sensor based on as-prepared NiO exhibits superior gas-sensing properties to CO. The results verified that the hollow structure of 2D nanoplates could enhance the gas sensing performance by providing sufficient gas diffusion pathways and reaction sites in the gas-sensitive process. • The novel 2D honeycomb-like NiO nanoplates assembled by nanosheet arrays were synthesize. • The possible growth mechanism of the honeycomb-like NiO nanoplates was discussed in detail. • The effect of hollow 2D honeycomb-like nanostructure on gas-sensing properties of NiO nanoplates was discussed. Herein, we successfully prepared the Nickel oxide (NiO) nanomaterials with the structure of two-dimensional (2D) honeycomb-like nanoplates assembled by nanosheet arrays through the hydrothermal synthesis. In addition, the growth mechanism of this unusual nanostructure was proposed. Surprisingly, such NiO nanoplates exhibits superior gas-sensing properties to CO, which is mainly attributed to the hollow structure produced by the arrangement of nanosheets, contributing not only enough gases diffusion pathways but sufficient reaction sites during the gas sensing processes. [ABSTRACT FROM AUTHOR]