*2.1. Synthesis of Nanoparticles*

Pure and Zn doped α-Fe2O<sup>3</sup> samples were synthesized by sol-gel method using high purity precursors Fe(NO3)3.9H2O and Zn(NO3)2.6H2O in a stoichiometry ratio with distilled water as solvent (as shown in Figure 1). The solutions were mixed and subjected to vigorous stirring for about 15 min to obtain a clear homogenous solution. The sol mixture was heated on hot plate at 60 ◦C with constant stirring for 1 h until the gel type solution was obtained. This gel was converted to solid particles by heating at 90 ◦C for 4 h and then crushed to get nanoparticles. The as obtained powder was annealed at 400 ◦C for 2 h and then grinded. The sample without doping is represented as pure Fe2O<sup>3</sup> and Zn doped as Zn 2%, Zn 4% and Zn 6% corresponding to samples α-ZnxFe2−xO<sup>3</sup> where x = 0, 0.02, 0.04 and 0.06.
