Study on the electronic band structure of ZnO–SnO₂ heterostructured nanocomposites with mechanistic investigation on the enhanced photoluminescence and photocatalytic properties.

Palai, Amrita; Panda, Nihar Ranjan; Sahoo, Mihir Ranjan; Sahu, Dojalisa

Sol–gel method of synthesizing nanocomposites (NCs) of two metal oxides (ZnO & SnO2) was implemented along with the pristine samples. The structural modulation occurred due to variable concentration of the above two materials in the NCs has been studied by x-ray diffraction (XRD) measurement. Hexagonal wurtzite phase of ZnO with tetragonal rutile phase of SnO2 was found to be formed for the NCs without any impurity phases. The alteration in the particle shape and morphology has been investigated by FESEM. Optical absorbance study shows that the band gaps of NCs are of an intermittent value compared to the band gaps of the individual oxides. The near band edge emission (NBE) of ZnO is absent in the photoluminescence (PL) emission spectra of NCs which may refer to a decrement in the direct recombination rate of electron–hole (e–h) pairs. Fast recombination of charge carriers is hindered due to the introduction of defect centers which results in the improvisation in visible emissions in the PL spectra of nanocomposites. The NCs have shown better efficiency in degrading phenol and Rhodamine B as compared to the pristine samples. Increased e–h separation efficiency is expected in the heterojunction along with the availability of more number of active sites leading to the above observation. Highly stable and reusable photocatalysts are formed relevant to different applications. In addition, first-principles density functional calculations show the composite heterostructure facilitates the transfer of photo-generated electrons due to decrease in the band gap.

ELECTRONIC band structure; BAND gaps; ELECTRON-hole recombination; PHOTOLUMINESCENCE; NANOCOMPOSITE materials; RUTILE

Journal of Materials Science: Materials in Electronics, 2022, Vol 33, Issue 12, p9599

0957-4522

Academic Journal

10.1007/s10854-021-07583-x