Catalytic oxidation of ibuprofen over bulk heterojunction photocatalysts based on conjugated donor-acceptor configured benzoselenadiazole molecule

Abstract

The use of photocatalysts for acquiring direct photon energy from sunlight is a promising way to clean the environment, particularly the remediation of contaminants from water. In this work, firstly π-conjugated organic semiconductor configuring benzoselenadiazole, 4-(3,5-bis(trifluoromethyl) phenyl)-7-(5'-hexyl-[2,2'-bithiophen]-5-yl)-benzo [c] (Kümmerer, 2009; Chen et al., 2018; Randeep et al., 201) selenadiazole, abbreviated as (RTh-Se-F), was synthesized. The designed RTh-Se-F with an extended π-conjugation showed good optical properties in the visible region and estimated a low optical band gap of ∼2.02 eV . The molecular orbitals i.e. HOMO (-5.33 eV) and LUMO (-3.31 eV) for RTh-Se-F organic semiconductor were suitably aligned to energy levels of (Madhavan et al., 2010Madhavan et al., 2010)-Phenyl-C₇₁-butyric acid methyl esters (PC₇₁BM) which resulted in the broadening of absorption and covering of entire visible region. RTh-Se-F was integrated with varied weight percentages (wt %) of PC₇₁BM to obtain bulk heterojunction (BHJ) and applied as efficient visible light driven BHJ photocatalyst for an effective oxidation of ibuprofen. RTh-Se-F@PC₇₁BM (1:2, wt %) BHJ photocatalyst showed the superior ibuprofen degradation of ∼93% within 90 min under visible light illumination. The maximum degradation rate by BHJ photocatalyst might be accredited to the broadening of absorption capacity and improved lifetime of photogenerated electron-hole pairs which might be resulted from high absorption properties of RTh-Se-F organic semiconductor.

Keywords: Benzoselenadiazole; Bulk heterojunction; Conjugated organic semiconductor; Ibuprofen; Photocatalyst; Visible light.