Evo 18 cryo sem

The nanoparticles and the core–shell
structure were analyzed by high-resolution transmission electron microscopy
(HRTEM) (FEI Tecnai G2 30S-TWIN, FEI Company, Hillsboro, OR). The
rheological characteristics of the ink were measured using a Rheo
plus32 rheometer (Anton Paar, Ashland, VA, USA) operating in both
rotational and oscillation modes. Screen printing was done through
semiautomatic screen printer (EKRA, Germany) which operated at a printing
speed of ∼30 cm/s. The ink was screen-printed on various substrates,
and the surface morphology was analyzed by using a scanning electron
microscope (Zeiss EVO 18 Cryo SEM, Jena, Germany). The surface roughness
of the printed film was analyzed by atomic force microscopy (AFM)
(MultiMode, Bruker, Germany). UV–vis spectra of the solution
state were recorded with a UV spectrophotometer (UV-1800 Shimadzu)
in the range of 200–900 nm. The absorption properties of the
printed pattern were characterized using a UV–vis near-infrared
source (Ocean Optics). Excitation and emission spectra of the solution
and film states were recorded with a Spex-Fluorolog FL22 spectrofluorimeter
equipped with a double grating 0.22 m Spex 1680 monochromator and
a 450 W Xe lamp as the excitation source.

The shape and size of the LDH were investigated
by SEM (Zeiss EVO 18 cryo-SEM) with an accelerating voltage of 20
kV. LDH suspension was directly drop-cast onto a carbon-coated grid
and imaged after natural drying at room temperature. Before imaging,
a thin layer of gold was evaporated onto the sample to avoid charging
and to improve contrast.