Innovative synthesis and properties of Fe doped nanocrystalline strontium zirconate for the development of visible light driven photocatalyst

Studies on the band gap engineering for photocatalysis and photovoltaic applications in SrZrO3 (SZO) being not explored. Here, we demonstrated a modified solid state reaction technique to prepare nanocrystalline perovskite with formula SrZr0.9Fe0.1O2.955 (SZFO). Phase analysis by X-ray powder diffractometry revealed the formation of only one orthorhombic phase with smaller crystallite size and enhanced lattice strain as Fe substitutes at Zr site. The availability of SZFO under study for the development of visible light driven photocatalysts was examined through diffused reflectance measurements. For the first time, a shift of the absorption edge to longer wavelength (red region) was observed. A narrowing of the optical band gap (Eg) to its half value (2.23 eV against 4.4 eV for pure sample) was achieved by Fe doping. Light absorbance was also found to drastically increase covering the UV-red region. These changes arose due to the distribution of Fe localized states at the O2p band edge and inside the forbidden gap. The effect of Fe incorporation was also examined by Raman and Mössbauer spectroscopies. Raman studies confirmed the presence of disorder and compositional fluctuations as Fe substitutes at the Zr site. Mössbauer analysis proved the presence of abundant Fe3+ (90%) and few Fe4+ species with distorted octahedral sites. The resultant oxygen deficiency balancing the charge neutrality was calculated. The detected ferromagnetic character was attributed to both super exchange and double exchange interactions. Works are in progress for further tuning of the band gap in SZFO as a promising material for photocatalytic and photovoltaic applications.