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The MoO 3 /Mo 4 O 11 /MoO 2 heterogeneous nanobelts was synthesized by hydrothermal method and PH 3 reduction. The reduction degree of the samples depend on the calcination temperature which further influence the complex permittivity of the sample. The textural properties and electromagnetic wave absorption performances of MoO 3 /Mo 4 O 11 /MoO 2 composites with various components compositions were thoroughly investigated. It is found that the belt-shaped MoO 3 /Mo 4 O 11 /MoO 2 composites with length of 200 nm and width of 70 nm exhibit porous surface features. Electromagnetic wave absorption evaluations show that formation of heterogeneous structure could significantly improve the impedance matching and the minimum reflection loss of MoO 3 /Mo 4 O 11 /MoO 2 can reach −59.2 dB at 10.8 GHz with the thickness of 4.6 mm. The bandwidth of MoO 3 /Mo 4 O 11 /MoO 2 below −10 dB is 9.5 GHz (7.5–17 GHz). The investigations on the absorption mechanism reveal that the high dielectric loss, suitable impedance matching and geometric shape effect contribute to the excellent electromagnetic wave absorption. These results indicate that MoO 3 /Mo 4 O 11 /MoO 2 possess potential application prospects in electromagnetic pollution abatement in the future. Image 1 • Preparing multicomponent composite from single component by controlling the calcination temperature. • Electromagnetic parameters is influenced by the reduction degree. • The buffer layer (Mo 4 O 11) enhances the impedance matching. [ABSTRACT FROM AUTHOR]

We report for the first time using pure cobaltous tungstate (CoWO 4) as an efficient ethanol sensor by controlling the Co3+-Co2+ redox couple in CoWO 4. The prepared Co x WO 4 has a flower-like structure self-assembled by a mesoporous microbelt. Moreover, the Co x WO 4 sensor with a Co3+/Co2+ ratio of 38.9% exhibits a high response (42.9–100 ppm ethanol), fast response/recovery time (11/13 s), low detection limit (0.42 ppm), as well as remarkable short-term and long-term repeatability. Notably, the Co x WO 4 sample maintains a constant response value over a wide range of humidity (30–90 RH%), manifesting its good anti-humidity properties. The outstanding sensing performance is owing to the Co3+-Co2+ redox couple, high surface area and moderate porosity of the obtained samples. The self-transforming of the Co3+-Co2+ redox couple contributes to the formation of absorbed oxygen (O 2 -), oxygen vacancies and the reduction of the band gap, which is a crucial factor in improving the sensing properties of Co x WO 4. • Pure cobalt tungstate was used for the first time as an efficient ethanol sensor. • The sensor shows a fast response/recovery time and low detection limit. • The self-transforming of Co3+-Co2+ redox on the surface is also a crucial factor. [ABSTRACT FROM AUTHOR]

Co 3 O 4 /CeO 2 nanoparticles decorated CNTs (Co 3 O 4 /CeO 2 /CNTs) composites were synthesized by a one-step hydrothermal route. The micro-structure examinations of the ternary composites indicated that the CeO 2 and Co 3 O 4 nanoparticles with size ranges of 5–10 nm were homogeneously deposited onto the CNTs surface. When applied for the attenuation of electromagnetic (EM) wave, the ternary Co 3 O 4 /CeO 2 /CNTs composites exhibit enhanced EM wave absorption properties than pure CNTs and previously reported CNTs based composites owing to the improved impedance matching and multiple polarization relaxations. The minimum reflection loss (RL) of the ternary composites reached − 59.82 dB at 11.92 GHz with a thin thickness of 1.73 mm, and the effective absorption bandwidth (RL < − 10 dB) covered as broad as 5.20 GHz (12.76–17.96 GHz) for a thickness of only 1.42 mm. These results demonstrated that the as-prepared Co 3 O 4 /CeO 2 /CNTs composites with a facile synthetic process and strong absorption performance could be a promising candidate for EM wave absorption. • Novel ternary Co 3 O 4 /CeO 2 /CNTs composites were successfully synthesized by a one-step hydrothermal route. • CeO 2 is a semiconductor with abundant oxygen vacancies, and Co 3 O 4 is a magnetic semiconductor. • The complementarity between multiple loss processes induced the excellent EM wave absorption properties. • The minimum RL of the composites reached − 59.82 dB，and the effective absorption bandwidth can reach up to 5.2 GHz. • Minimum RL and effective absorption bandwidth were obtained with very thin thickness. [ABSTRACT FROM AUTHOR]

In this work, nanocomposites with NiMoO 4 nanorod as core and NiMoS 4 nanosheet as shell with controlled sulfidation manner was obtained by one-step hydrothermal method. Characterization methods like scanning electron microscope and X-ray photoelectron spectrometer confirmed the well-designed core-shell structure and precisely-tuned composition. It exhibited superior electrochemical properties of high specific capacitance (832.3 F g−1 at current density of 5 A g−1), outstanding rate capability and stable cycling performance. With resultant as anode and reduced graphene oxide (rGO) as cathode, an asymmetric supercapacitor (ASC) was assembled and presented high energy density of 22.84 W h kg−1. Besides, cycling performance of the device is so outstanding that the capacity retention was up to 117.4% after 5000 cycles. Benefited from the synergistic effect between NiMoS 4 and NiMoO 4 components, large specific surface area and effective electron transportation from nanorod @ nanosheet structure, the excellent electrochemical performance indicates a good prospect of the material in the energy storage field. Image 1 • Complementary composition and well-designed structure was obtained simultaneously. • The resultant shows outstanding capacitive properties. • Assembled asymmetric supercapacitor exhibits excellent cycling performance. [ABSTRACT FROM AUTHOR]

• Pt-WO 3 nanorods are synthesized via hydrothermal and chemical reduction method. • The sensor based on Pt-WO 3 shows excellent comprehensive performance with high sensitivity and fast response/recovery speed. • The minimum detection limit of Pt-WO 3 based sensors to H 2 S was as low as 5 ppb. • The electron sensitization and chemical catalysis of Pt nanoparticles greatly enhanced the gas sensing properties of WO 3. [Display omitted] The Pt-loaded WO 3 materials have been synthesized via simple hydrothermal and chemical reduction methods. The microstructure of prepared Pt-WO 3 exhibits as nanorods consisting of bundles of finer nanorods and the Pt nanoparticles with a size of ca. 5 nm loaded on the surface of WO 3. The gas sensing measurements of Pt-WO 3 material show excellent gas sensing selectivity to H 2 S compared with many other pollution gases (e.g. NO 2 , SO 2 , NH 3 , CO and CO 2). In particular, 0.2 at% Pt-WO 3 exhibits extremely high response (1638–10 ppm H 2 S), short response/recovery time (42 s/37 s) and low detection limit (1.27–5 ppb H 2 S) at 200 °C. The superior performance of 0.2 at% Pt-WO 3 compared with pure WO 3 mainly originate from its modulating action to conductive band electrons of WO 3 and its catalysis to the chemisorption reaction on the surface. [ABSTRACT FROM AUTHOR]

• The Pt deposited porous SnO 2 nanospheres were synthesized by hydrothermal and chemical reduction method. • The Pt-SnO 2 sensors exhibited an overall enhanced formaldehyde sensing performance compared with the pure SnO 2. • The 1 wt% Pt-SnO 2 exhibited higher response (16.03), high-speed response time (9 s) and outstanding selectivity. This work constructs a Pt-SnO 2 sensor materials with the porous structures and catalytic effect, which great enhanced the sensing performance towards formaldehyde. [Display omitted] Formaldehyde is one of the most serious threats to human health in modern interior decoration. Thereby, online detection of indoor formaldehyde concentration has become an urgent problem. In this work, the Pt deposited porous SnO 2 nanospheres were synthesized as the formaldehyde sensing materials, which were prepared by hydrothermal and chemical reduction methods. The diameter of as-synthesized Pt-SnO 2 were centered in the range of 30–50 nm, with the dominant pore size of ~10 nm and the specific surface area of 89.79 m2 g−1, which provided a raft of passages and active sites for gas molecules to diffuse and interact mutually. Moreover, the experimental results demonstrated that the 1 wt.% Pt-SnO 2 exhibited higher response (16.03), high-speed response time (9 s) and outstanding selectivity with exposure to low-concentration formaldehyde compared with original SnO 2. The porous structures and catalytic effect of Pt nanoparticles were jointly responsible for the enhancement of SnO 2 on sensing performance towards formaldehyde. [ABSTRACT FROM AUTHOR]

• A specific and feasible method to fabricate specially designed one-dimensional structure. • A complicated nanostructure of the flakes-assembled porous ZnO/Ni hybrid nanotubes. • Revealing the inner attenuation mechanism of enhanced electromagnetic absorption performances. Flakes-assembled ZnO/Ni hybrid nanotubes were synthesized by electrospinning with hydrothermal treatment, calcination and reduction reaction for the electromagnetic wave absorption. The synergy effects between ZnO and Ni and absorbing mechanisms were investigated. [Display omitted] Electromagnetic (EM) wave absorption materials with excellent absorption performances are highly desirable because of military applications and EM radiation pollution protection. In this work, we have synthesized and demonstrated the flakes-assembled porous ZnO/Ni hybrid nanotubes by combining electrospinning and hydrothermal reaction, coupled with following calcination and reduction process. The rational-designed ZnO/Ni nanocomposites exhibited extremely superb EM wave absorption property with a minimum reflection loss (RL) of −71.2 dB at 15.3 GHz, corresponding to a thickness of 3.4 mm and the maximum effective absorption bandwidth (RL≤–10 dB) is up to 9.4 GHz (8.6–18.0 GHz) with the thickness of 4.2 mm. The significant performance improvement originated from that the unique three-dimensional architecture optimized impedance matching characteristics and magnetic-dielectric synergetic effect contributed to a strong attenuation capacity. This work provided a feasible strategy to synthesize flakes-assembled nanotube microstructure and the ZnO/Ni composites promised great potential in the EM wave absorption fields. [ABSTRACT FROM AUTHOR]

Nitrogen doping has been proven an efficient strategy to modulate the electronic structure of metal oxides to tune their properties. Herein, we report the synthesis of N-doped SnO 2 microspheres through calcining the pristine SnO 2 in NH 3 atmosphere. Texture characterizations show that N–SnO 2 microspheres exhibit 3D-porous architectures with a diameter of ca. 300–500 nm. After NH 3 treatment, the SnO 2 exhibits the formation of the N-doping and oxygen vacancies on the surface of the material, rich free-electrons and the narrow energy band. It is found that the as-prepared N-doped SnO 2 microspheres at 200 °C (N–SnO 2 -200), show superior selectivity and high response (S = 155 to 5 ppm NO 2) compared with its counterparts. DFT calculations and experimental results illustrate that N impurities and oxygen vacancies as N-induced active sites favor the adsorption of NO 2 molecules; rich free-electrons increase the amount of adsorbed NO 2 molecules; and the narrow energy band promotes the effectively electron transfer during the sensing reaction. Therefore, in this work we unravel the improved NO 2 gas-sensing performances of the N-doped SnO 2 and provide new guidance for the development of highly efficient metal oxide sensing materials for NO 2 detection. • The N-doped SnO 2 nanospheres were synthesized via NH 3 heat treatment of the pristine SnO 2. •The correlation between the content of N doping and the gas-sensing property was further studied. •The N–SnO 2 nanospheres obtained at 200 °C shows improved response and selectivity to NO 2 at 80 °C. •The improved sensing mechanism of the N–SnO 2 sensor to NO 2 was further studied via DFT calculation. [ABSTRACT FROM AUTHOR]