Understanding the role of Ni ions on the photocatalytic activity and dielectric properties of hematite nanostructures: An experimental and DFT approach

Abstract

In this work, we have synthesized nickel-doped hematite α-Fe2−xNixO3 (x = 0.00, 0.02, 0.04, and 0.06) nanostructures using a hydrothermal method for its potential application in wastewater treatment. Various structural parameters, band gap, and dielectric measurements indicate a particular trend upon gradually increasing the Ni content up to x = 0.04 in the host matrix and this trend reverses upon further increasing the amount of Ni-doping. This indicates that Ni ions are uniformly distributed in the α-Fe2O3 matrix up to this concentration and a non-uniform distribution takes place thereafter. Transmission electron microscopy indicates the growth of a flower-like structure in all the studied samples. We have also performed electronic structure calculations using first principle density functional theory plus Hubbard U method for the analysis of experimental band gap and to understand the correlation effect due to Ni-doping. The photocatalytic activity was performed for rose bengal dye and up to 80% of dye degradation was achieved in x = 0.04 Ni concentration. Hence, we confirm that Ni-doping in α-Fe2O3 makes it suitable for water purification against this harmful dye.