Improved Visible Light Photoactivity of CuBi₂O₄/CuO Heterojunctions for Photodegradation of Methylene Blue and Metronidazole

Abstract

Herein, a one-step solvothermal method was applied to produce CuBi2O4/CuO heterojunctions containing nanocolumns with small platelike nanoparticles homogeneously distributed over its surface. The photocatalytic activity of the heterojunctions was evaluated through the photodegradation of Methylene Blue (MB) dye and Metronidazole (MTZ) under simulated solar light and visible light irradiation, respectively. The heterojunction CuBi2O4/CuO-b showed an enhanced photocatalytic performance with 98% removal of MB (@2 sun simulated solar irradiation) and 36% removal of MTZ (@1 sun visible light) within 60 min of irradiation, compared to the results obtained with the pristine materials (CuO and CuBi2O4) or the other composite synthesized CuBi2O4/CuO-a. The apparent quantum efficiency for MB photocatalytic degradation using the optimized photocatalyst and 180 min of light irradiation is ∼2.1%, under the excitation wavelength of 540 nm. This enhanced photocatalytic performance is a result of an effective charge separation through a type-II heterojunction, indicating that photoinduced electrons transfer from CuBi2O4 to CuO nanoparticles and the photoholes migrate in the opposite direction. The main reactive species responsible for the photocatalytic degradation of the organic pollutant molecules were the photogenerated holes. Finally, the best photocatalysts were reused and presented good stability over three cycles, endorsing their promise as candidates for photocatalytic applications.

Black TiO2 Thin Films Production Using Hollow Cathode Hydrogen Plasma Treatment: Synthesis, Material Characteristics and Photocatalytic Activity

“…The radiation emission spectrum of these lamps is shown in Figure 9c. The lamps were fixed at a distance of 70 mm from the samples, which have an active area of 2 × 2 cm 2 , delivering an irradiance of 2.2 mW.cm −2 at the sample position which was measured using a calibration cell (Abet Tech, model 15151, Milford, KS, USA), as reported elsewhere [66,67]. It is important to note that the main emission peak of the lamp (250 nm) is not detected by this reference cell who operates between~300-1100 nm and, therefore, the irradiance can be slightly higher than the value herein reported.…”

A Mini Review on Bismuth-Based Z-Scheme Photocatalysts

“…The poor solar energy utilization capacity leads to the low quantum efficiency and the practical application of TiO 2 is greatly limited [ 35 , 36 ]. Considering that visible light energy accounts for about 45% of sunlight energy [ 37 ], subsequently, in order to broaden the light-harvesting range, remarkable efforts have been devoted to explore visible light-activated semiconductors including CdSe, CdS, SiC, WO 3 , Fe 2 O 3 , Co 3 O 4 , g–C 3 N 4 , CdO, Ag 2 O et al as photocatalysts, which possess a narrow band gap that is less than or equal to 3.0 eV. Recently, bismuth-based (Bi-based) semiconductors with advantages of non-toxicity, low cost and good thermal stability and as new and important visible light-activated semiconductors have become a research hotspot [ 20 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ].…”

Recent advances in photodegradation of antibiotic residues in water

“…The reaction mechanisms of semiconductor photocatalysis are typically expressed by the following equations [45] , [46] :…”