Structural, Electronic and Zinc Doping Effect on the Catalytic and Optical Properties of Lanthanum Orthochromite Perovskite: Experimental and Theoretical Study

In this work, lanthanum orthochromite (LaCrO3; LCO) and lanthanum orthochromite doped with zinc in the B site ((LaCr1–xZnxO3: x = 0.1, 0.2, 0.3; LCZO) were synthesized by the sol–gel citrate route and investigated with respect to their crystal structure, surface morphology and optical band gap energy by means of X-ray diffraction, scanning electron microscopy and UV–Vis spectrophotometry. Moreover, the band structure, density of states (DOS) and electronic density were calculated for LCO using the DFT–FP–LAPW method. The XRD analysis showed that LCO sintered at 1000°C and LCZO sintered at 1100°C crystallize in a perovskite-type orthorhombic structure. The computed band gap energy was about 2.93 eV for pure LCO oxide. On the other hand, the experimental results showed a remarkable decrease in the LCO optical band gap from 3.0 to 2.7 eV with increased Zn content. The prepared systems were also tested with respect to their catalytic activity in the oxidative dehydrogenation of 1-butene, where doping with Zn was found to improve the catalytic performance of LCZO catalysts, leading to a maximum selectivity to 1,3-butadiene of 35% at a zinc doping level of x = 0.2.