Cu2+-doped α-β phase heterojunctions in Bi2O3 nanoparticles for enhanced photocatalytic degradation of organic dye rhodamine B

alpha-beta Bi2O3 modified with Cu2+ ions in various compositions have been synthesized by hydrothermal process. The crystallinity, surface structure, elemental compositions and optical characteristics were uncovered by relevant techniques including XRD, SEM, EDX, XPS, PL, and UVDRS. Total organic carbon (TOC) analysis was performed to determine the dye degradation efficiency of photocatalyst. Highly crystalline Bi2O3 nanoparticles consisting of alpha-beta phase heterojunctions were observed possessing crystallite sizes in the range of 30-40 nm. The photocatalytic activity of Cu2+-modified Bi2O3 composites was studied using RhB dye under the illumination of visible light. The results reveal that addition of Cu2+ ions into Bi2O3 lattice significantly improved the degradation rate over the pure sample. The highest activity was obtained for sample containing 2 mol % Cu in Bi2O3 lattice where complete degradation of the pollutant was attained in 120 min. The increased activity is largely ascribed to the effective separation of charge carriers due to Cu2+ doping and formation of alpha-beta phase heterojunctions in Bi2O3.The effect of pH conditions and role of active species on degradation kinetics were also examined.