Effect of Bi3+ Ion Concentration on Physicochemical, Optical and Catalytic Properties of One‐Pot Combustion Synthesized Nanocrystalline Bi‐Doped La2O3

La2‐2xBi2xO3 (x=0‐0.04) nanocrystalline powders are synthesized by one‐pot single step solution combustion method. 4 atom% Bi doped La2O3 reveals the presence of both Bi3+ and metallic Bi. Temperature programmed reduction (TPR) of La2O3 and La2−2xBi2xO3 (x=0.005‐0.04) indicates that the oxygen storage capacity changes with the dopant (Bi) concentration. La2‐2xBi2xO3 (x=0.04) has less hygroscopic behavior compared to La2O3 and shown enhanced stability in an open atmosphere. The direct band gap of La2O3 and La(OH)3 decreases significantly after Bi doping. Further, PL studies of Bi doped compounds show a blue emission at 458 nm due to 3P1 ‐ 1S0 transition of the Bi3+ ion substituted in La2O3. Emission intensity is maximum with 0.5 atom percent Bi doping, which decreases gradually with increasing Bi3+ ion concentration. Bi doping also modifies the catalytic activity of La2O3, resulting in higher CO oxidation activity than unsubstituted La2O3. La2O3, La2O3 doped with various Bi ions concentrations (La2‐2xBi2xO3, x (atom%)=0.005‐0.04) and Bi2O3 have been synthesized by a solution combustion method using oxalyldihydrazide (ODH) as fuel and studied their catalytic and photoluminescence properties. Bi doped La2O3 compounds show higher activity for CO oxidation reaction when compared to La2O3 and Bi2O3 alone. La1.92Bi0.08O3 (4 atom% Bi doped La2O3) show higher catalytic activity compared to other chosen catalyst. On the other side, 0.5 atom% Bi doped La2O3 (La1.99Bi0.01O3) shows higher emission intensity (shown in the inset of the figure) compared to other Bi doped La2O3 compounds.