Materials Chemistry and Physics 263 (2021) 124360
Available online 6 February 2021
0254-0584/© 2021 Elsevier B.V. All rights reserved.
Structure, microstructure and photocatalytic properties of embedded
spherical Cu nanoparticles on Cu
2
O–SiO
2
Ritayan Chatterjee
a, *
, Sven Lidin
b
, Sulava Bhattacharyya
c
, Saikat Kumar Kuila
d
a
Department of Physics, Heritage Institute of Technology Kolkata, East Kolkata Township, Kolkata, 700107, India
b
Department of Chemistry, Lund University, Box 124, SE-22100, Lund, Sweden
c
Department of Physics, Jadavpur University, Kolkata, 700032, India
d
Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, West Bengal, 721302, India
HIGHLIGHTS G R A P H I C A L ABSTRACT
• Cu nanospheres of 4–34 nm diameter
embedded on Cu
2
O–SiO
2
(Cu
np
-Cu
2
O/
SiO
2
) is produced from chalcopyrite
concentrate.
• Sulfur is removed through an environ-
ment friendly process; the final prod-
uct’s impurities are extremely low.
• Detailed characterizations (XRD; TEM;
UV–Vis, PL, FTIR and Raman spectros-
copies) of Cu
np
-Cu
2
O/SiO
2
are reported.
• Low band gap energy of 1.4 eV is ob-
tained, the existence of two donor levels
below the conduction band are detected.
• Photocatalytic performance is promising
under solar light irradiation with BB
degradation efficiency of 71.26 % in 90
min.
A R T I C L E INFO
Keywords:
Cu
np
-Cu
2
O/SiO
2
Rietveld refinement
Microstructure
Low band gap energy
Solar light photocatalysis
ABSTRACT
Nanosized spherical copper particle embedded on oxide matrix (Cu
np
-Cu
2
O/SiO
2
) is synthesized from a low cost
chalcopyrite concentrate. The concentrate is reduced by hydrogen at 1323 K, followed by acid leaching to
produce Cu
np
-Cu
2
O/SiO
2
. Powder X-ray diffraction confirms the formation of metallic copper as the principal
phase along with oxides of silicon and copper. The weight fractions of Cu, SiO
2
and Cu
2
O are 0.565(8), 0.203(2)
and 0.232 (3) respectively, as obtained from a three-phase Rietveld refinement. The diameter of copper spheres,
rooted on silica, as observed in transmission electron microscopy, is ranging between 4 and 34 nm. Spectroscopic
studies, especially Raman spectra, confirm the occurrence of Cu
2
O. Raman active 2nd overtone at 219 cm
1
appears as the most intense peak. Contribution of SiO
2
is clear in Fourier transform infrared spectra. A broad
band between 1000 and 1100 cm
1
, more specifically at 1080 cm
1
occurs due to Si–O–Si asymmetric stretches.
The presence of Cu
2
O causes photoluminescence peaks to appear in the visible region, corresponding to energy
gaps of 0.9 and 1 eV, which indicate the existence of two donor levels below the conduction band. Broad ab-
sorption wavelength in the ultraviolet–visible absorption spectra in visible region and low band gap energy of
1.4 eV indicate the possibility of Cu
np
-Cu
2
O/SiO
2
to be an excellent photocatalytic material. The composite’s
photocatalytic performance as it is directly derived from the concentrate is quite promising under solar light
* Corresponding author.
E-mail addresses: ritayan.chatterjee@heritageit.edu, ritayanchatterjee@gmail.com (R. Chatterjee).
Contents lists available at ScienceDirect
Materials Chemistry and Physics
journal homepage: www.elsevier.com/locate/matchemphys
https://doi.org/10.1016/j.matchemphys.2021.124360
Received 10 September 2020; Received in revised form 18 January 2021; Accepted 3 February 2021