Photoelectrocatalytic Degradation Of RhB With Bi₂OO₃/NF Under Simulated Sunlight

Rhodamine B（RhB）is a basic xanthene-based dye,widely used in the dyeing and textile industries.Due to the wide application and unreasonable disposal of RhB,RhB-containing wastewater can pose a potential threat to human life and health as well as the ecological environment when it enters water bodies.As an environmentally friendly and efficient new treatment technology,photoelectric catalytic oxidation technology has significant advantages in degrading organic pollutants.（1）Bi₂O₃/NF photoanode was prepared on nickel foam substrate by microwave irradiation method.The preparation conditions of Bi₂O₃/NF were optimized by single factor experiment.Under the conditions of impregnation concentration of 1.00 mol·L^-1,microwave power of 350 W and microwave time of 6 min,the prepared Bi₂O₃/NF photocatalytic activity was the highest.（2）The structure and properties of Bi₂O₃/NF were characterized by SEM,XRD,XPS,PL,UV-vis DRS,etc.The results of SEM and XRD showed that the prepared catalyst was tetramonal Bi₂O₃ and distributed on the nickel foam framework in a flower cluster.The results of UV-vis DRS and PL show that the maximum absorption wavelength of Bi₂O₃/NF is 640 nm,and the Bi₂O₃/NF prepared at the concentration of 1.00 mol·L^-1 has good light absorption capacity in the visible region.The service life and XPS analysis of the catalyst show that Bi₂O₃/NF has good stability,and the removal rate of RhB can still reach 74.1%after four cycles of degradation.（3）The electrochemical properties of Bi₂O₃/NF were measured by EIS,i-t,OCPT,LSV and CV methods.The results show that the charge transfer resistance of Bi₂O₃/NF can be decreased,the active site on the surface of the photoanode Bi₂O₃/NF can be increased,and the photocurrent density and photoresponse can be improved by adjusting the concentration of the impregnating solution.The Mott-Schottky curve results show that the photogenerated carrier density of Bi₂O₃/NF after optimized load can reach 8×10²⁷cm^-3.（4）The photocatalytic oxidative degradation of RhB by Bi₂O₃/NF was studied under simulated sunlight.The effect of reaction conditions on the photocatalytic degradation efficiency was investigated.The photocatalytic efficiency of Bi₂O₃/NF degradation of RhB reached 95.35%after 150 min reaction at 2 V bias,8 mg·L^-1 initial concentration of RhB,p H 3 and 0.05 mol·L^-1 concentration of electrolyte Na₂SO₄.The effects of Cl^-and NO₃^-co-existing in water on the photocatalytic degradation of RhB by Bi₂O₃/NF were studied.The results showed that the presence of Cl^-and NO₃^-would reduce the production of·OH and the photocatalytic degradation efficiency of RhB by Bi₂O₃/NF.（5）The p H value of Bi₂O₃/NF solution during the degradation of RhB by photocatalytic oxidation was studied.The p H value of the solution rose first in the initial stage of the reaction,and then became stable with the end of the photocatalytic reaction.The mineralization rate of RhB degraded by Bi₂O₃/NF photocatalytic oxidation can reach67.6%.Free radical capture experiments show that h⁺,·OH and·O₂^-are the main active substances,which inhibit the recombination of photogenerated electrons and hole pairs under the action of applied voltage.Under the condition of simulated sunlight,the Bi₂O₃/NF photoanode is photoexcited to generate h⁺,·OH and·O₂^-and other free radicals.RhB was oxidized to CO₂ and H₂O under the synergistic action of various free radicals,and the photocatalytic degradation of RhB by Bi₂O₃/NF was in accordance with the first-order kinetic equation.