Enhanced Photocatalytic Activities for Degradation of Dyes and Drugs by Crystalline Bismuth Ferrite-Modified Graphene Hybrid Aerogel

Abstract

Industrial wastewater contains diverse toxic dyes and drugs, which pollute the environment and poison creatures. Utilizing photocatalysts has been accepted to be an effective method to degrade water pollutions using solar light. Crystalline bismuth ferrite (Bi2Fe4O9) with a band gap of 1.9–2.0 eV is expected to be one of the most promising candidates for photocatalysts in the visible light region. Amorphous graphene is also a promising candidate as a photocatalyst owing to its excellent electronic and optical properties. Herein, a composite of Bi2Fe4O9/graphene aerogels (GAs) was prepared with a two-step hydrothermal method. The prepared Bi2Fe4O9 powders were confirmed to be successfully doped into GAs and evenly dispersed between graphene sheets. The Bi2Fe4O9/GA composite was utilized to perform photodegradation for organic dyes and antibiotic drugs under visible light irradiation, yielding efficiencies of 90.22%, 92.3%, 71.8% and 78.58% within 330 min for methyl orange, methylene blue, Rhodamine B and tetracycline hydrochloride, respectively. Such distinct photocatalytic activities overwhelmed the pure Bi2Fe4O9 powders of 14.10%, 22.19%, 13.98% and 48.08%, respectively. Additionally, the composite produced a degradation rate constant of 0.00623 min−1 for methylene blue, which is significantly faster than that of 0.00073 min−1 obtained by the pure powder. These results provide an innovative strategy for designing 3D visible-light-responsive photocatalysts combined with graphene aerogel for water purification.