UiO-66/BiOBr heterojunction functionalized cotton fabrics as flexible photocatalyst for visible-light driven degradation of dyes and Cr(VI)

The development of green and efficient methods for removing multiple contaminants including combined organic and inorganic pollutants is imperative and yet challenging in view of practical applications. Herein, we present the preparation, characterization and performance of UiO-66/BiOBr heterojunction functionalized cotton fabrics (CFUB), which is a new photocatalyst constructed by assembling the components of metal-organic frameworks UiO-66 and BiOBr onto cotton fabrics via solvothermal reactions. CFUB was not only capable to remove rhodamine B (RhB) or Cr(VI), respectively, as single pollutant under simulated visible light irradiation, but also exhibited highly improved performance in simultaneously degrading binary RhB and Cr(VI) pollutants. CFUB could degrade single RhB efficiently in 40-80 min within acidic to neutral pH ranges, while single Cr(VI) in a solution at pH 2.5 was almost totally reduced to Cr(III) in 80 min. When a mixed solution containing RhB and Cr(VI) under pH 2.5 was irradiated, CFUB could completely remove RhB and Cr(VI) in 20 and 60 min, respectively. The enhanced activity of CFUB was ascribed to the improved visible light absorption intensity and promoted separation and transfer of charge carriers endowed by the fabrics bound UiO-66/BiOBr heterojunctions. CFUB showed excellent stability and reusability and the tests on several dyes stains also demonstrated that CFUB possessed good visible-light driven self-cleaning property. The possible mechanisms for employing CFUB to eliminate single RhB and Cr(VI) or their mixture were put forward. This work may introduce a portable, durable and recyclable textile based photocatalyst with multifunctional applications.