Facile synthesis of Ni-doped tetrahedral γ-Bi2O3 and selective photocatalytic degradation of Congo red under simulated sunlight

Ni-doped gamma-Bi2O3 was successfully synthesized via a one-pot oil bath synthesis. The prepared materials were characterized by XRD, DLS, SEM, FT-IR, EDS, TEM, and XPS. The XRD patterns confirmed the pure phase formation of tetrahedral gamma-Bi2O3. The material was tested for the degradation of various organic dyes and exhibited outstanding efficiency and selectivity for the photodeterioration of Congo red compared to other organic dyes. Furthermore, different Ni percentages were doped to find the best possible photocatalyst for Congo red degradation, with the 2 % Ni-doped gamma-Bi2O3 exhibiting an improved performance. The photocatalytic degradation efficiency of Congo red reached 93 % after 80 min and was used for three consecutive cycles without a considerable decrease in activity. UV-visible DRS spectra and the Mott-Schottky plot were used to understand the energy diagram of the materials. The higher visible light absorption and charge separation efficacy of the photogenerated electron-hole pairs induced by Ni loading contributed to improved photocatalytic performance. This study introduces a novel method for synthesizing Ni-doped tetrahedral gamma-Bi2O3 microstructures with precisely controlled morphology for the selective degradation of Congo red dye.