Crystal facets effect of tin dioxide nanocrystals on photocatalytic degradation and photo-assisted gas sensing properties

Crystal facets effects have been widely concerned in the field of photocatalysis and gas sensing in recent years. However, little attention have been paid to the crystal facets effect of...

Fabrication of three-dimensional nitrogen-doped reduced graphene oxide/tin oxide composite aerogels as high-performance electromagnetic wave absorbers

Developing light-weight and high-efficiency electromagnetic wave (EMW) absorbers has been considered as an effective strategy to resolve the electromagnetic radiation pollution problem. Herein, nitrogen-doped reduced graphene oxide/tin oxide (NRGO/SnO₂) composite aerogels were facilely prepared through the hydrothermal process and subsequent lyophilization treatment. Morphological characterization results manifested that the attained NRGO/SnO₂ composite aerogels possessed unique three-dimensional (3D) porous network structure constituted by the tiny SnO₂ nanoparticles decorated wrinkled surfaces of flake-like NRGO. Moreover, excellent EMW absorption performance could be achieved through facilely regulating the additive volumes of ethylenediamine and filler contents. Impressively, the composite aerogel with a doped nitrogen concentration of 6.5 wt% displayed the optimal minimum reflection loss of -62.3 dB at a matching thickness of 3.5 mm and the broadest effective absorption bandwidth of 5.1 GHz under an ultrathin thickness of merely 1.6 mm. Furthermore, the as-synthesized composite aerogels showed a light-weight characteristic with the low bulk density of 19.9-25.7 mg·cm^-3. Additionally, the potential EMW absorption mechanisms of obtained composite aerogels were revealed, which were mainly ascribed to the unique 3D porous network structure, synergistic effects between conduction loss and polarization loss, as well as the balanced attenuation loss and impedance matching. This work could be valuable for the structural design and fabrication of 3D graphene-based dielectric composites as light-weight and high-efficiency EMW absorbers.

Lightweight and Hydrophobic Three-Dimensional Wood-Derived Anisotropic Magnetic Porous Carbon for Highly Efficient Electromagnetic Interference Shielding

Constructing multifunctional characteristics toward advanced electromagnetic interference shielding materials in harsh environments has become a development trend. Herein, the wood-derived magnetic porous carbon composites with a highly ordered anisotropic porous architecture were successfully fabricated through a pyrolysis procedure. The three-dimensional porous skeleton inherited from the wood stock serves as an electrically conductive network and incorporates magnetic Ni nanoparticles homogeneously and firmly embedded within the carbon matrix that can further improve the electromagnetic attenuation capacity. The optimized Ni/porous carbon (PC) composite exhibits an exceptional electromagnetic interference (EMI) shielding effectiveness of 50.8 dB at the whole X band (8.2-12.4 GHz) with a low thickness (2 mm) and an ultralow density (0.288 g/cm³) and simultaneously possesses an extraordinary compressive strength (11.7 MPa) and a hydrophobic water contact angle (152.1°). Our study provides an alternative strategy to utilize green wood-based materials to design multifunctional EMI shielding composites.

Nanoparticles decorated carbon nanotubes as novel matrix: A comparative study of influences of immobilization on the catalytic properties of Lensculinarisβ-galactosidase (Lcβ-gal)

In the present study, Multiwalled carbon nanotubes (MWCNT) decorated with two different nanoparticles namely tungsten disulfide (WS₂) and tin oxide (SnO₂), nanocomposites (NCs) were synthesized via hydrothermal method. Spectroscopic studies showed that both synthesized NCs possess nearly same functional groups but MWCNT-SnO₂ NCs are rich in O-functional group. Microscopic studies revealed that both NCs have different morphological microstructure. Lens culinaris β-galactosidase (Lcβ-gal) was immobilized using glutaraldehyde cross-linker resulted in immobilization efficiency of 91.5% and 88% with MWCNT-WS₂ and MWCNT-SnO₂ NCs, respectively. Remarkable increase in rate of hydrolysis of whey lactose has been observed with both NCs i.e. Lcβ-gal immobilized MWCNT-WS₂ hydrolyzes the 97% whey lactose in 1.5 h while MWCNT-SnO₂ showed maximum 92% of whey hydrolysis in 2 h at optimum conditions. Both nanobiocatalyst could serve as a promising candidates for dairy industries and would offer a potential platform for enzyme based biosensor fabrication.

Enhanced Polarization from Hollow Cube-like ZnSnO3 Wrapped by Multiwalled Carbon Nanotubes: As a Lightweight and High-Performance Microwave Absorber

Polarization and conduction loss play fundamentally important roles in the nonmagnetic microwave absorption process. In this paper, a uniform and monodisperse hollow ZnSnO₃ cube wrapped by multiwalled carbon nanotubes (ZSO@CNTs) was successfully synthesized via facile hydrothermal treatment. A reasonable mechanism related to Ostwald ripening was proposed to design the varied ZSO@CNTs for the special hollow conductive network. Scanning electron microscopy images clearly indicate that reaction temperature is the key factor for the composite structure, which has a significant effect on its electromagnetic properties. Electron holography proves the inhomogeneous distribution of charge density in the ZSO@CNT system, leading to the occurrence of interface polarization. Complex permittivity properties of ZSO@CNT composites under different reaction temperatures were investigated to optimize the morphology that can distinctly enhance microwave absorption performance. The maximum reflection loss that the ZSO@CNT-130 °C composite can reach is -52.1 dB at 13.5 GHz, and the absorption bandwidths range from 11.9 to 15.8 GHz with a thickness as thin as 1.6 mm. Adjusting the simulation thicknesses from 1 to 5 mm, the efficient absorption bandwidth (RL < -10 dB) that the ZSO@CNT composite could reach was 14.16 GHz (88.8% of 2-18 GHz). The excellent microwave absorption performance may be attributed to the synergistic effects of polarization, conduction loss, and special hollow cage structure. It is proposed that the specially controlled structure could provide an effective path for achieving a high-performance microwave absorber.

Excellent microwave absorption properties of Fe ion-doped SnO2/multi-walled carbon nanotube composites

Fe ions doped SnO₂/MWCNTs composites with 48.8% Fe ions doping content showed the maximum reflection loss was −44.54 dB at 15.44 GHz, and the maximum absorption bandwidth of reflection loss below −10 dB was 4.5 GHz in the Ku band.

Facile synthesis of net-like Fe3O4/MWCNTs decorated by SnO2 nanoparticles as a highly efficient microwave absorber

SnO₂ nanocrystals were introduced into Fe₃O₄/MWCNTs to tune the complex permittivity. The synergistic interaction of different components and special net-like structure contribute to a highly efficient MA.