The XRD spectrum of the synthesized CuO nanosheets is given
in Fig. 2a. All the diffraction peaks in Fig. 2a can be well indexed
to the pure single-phase CuO with monoclinic structure (JCPDS
45-0937) [34]. No other crystallographic phases or other impurities
such as Cu2O or Cu(OH)2 were detected, indicating that the synthesized
sample was pure. Also, the sharp diffraction peaks in the XRD
spectrum of the synthesized sample indicate that well-crystallized
single-phase CuO nanosheets can be readily obtained by the proposed
method (ultrasonic assisted precipitation). Fig. 2b and c
show the SEM image of the CuO nanosheets at different magnifications.
The low magnification SEM image in Fig. 2b shows that the
synthesized sample is composed of sheet-like nanostructures.
Moreover, the high magnification SEM image in Fig. 2c demonstrates
that the nanosheets were randomly oriented. Furthermore,
the width and thickness size distribution of nanosheets were calculated
by manual microstructure distance measurement software.
The results showed that the width and thickness size
distribution are in the range of 50–100 and 30–40 nm, respectively