Photodegradation, DFT and electrochemical studies of carbon nanohorns modified BiSbO 4 /BiSbS 3 heterostructure for an endocrine disrupting agent pentachlorophenol

Abstract

Development of a photocatalyst with good efficiency and recyclability is demanding heavily to degrade endocrine disrupting chemicals from wastewater. In this study, degradation of an endocrine disrupting agent (pentachlorophenol) is performed by using photocatalysts BiSbO₄, BiSbS₃ and carbon nanohorns (CNH) modified BiSbO₄/BiSbS₃ heterostructure nanocomposite (BiSbO₄/BiSbS₃/CNHs) under visible light. To get structural, morphological, textural insights, the photocatalysts are characterized by XRD, SEM-EDX, TEM, UV, PL, FTIR and BET techniques. Band gap plays a dynamic role in photocatalysts and band gap of photocatalysts is determined to be 3.20, 2.82 and 2.69 eV for BiSbS₃, BiSbO₄ and BiSbO₄/BiSbS₃/CNHs respectively. All the photocatalysts show high degradation at pH value of 6. The rate constant (K_app) and R² calculated form of pseudo first order reveals that the heterostructure BiSbO₄/BiSbS₃/CNHs is more efficient in degradation of pentachlorophenol as compared to BiSbO₄ and BiSbS₃. Among the three photocatalysts, BiSbS₃ is observed to be comparatively less efficient because oxides are considered more pivotal in photocatalysis as compared to sulphides. The effect of scavengers shows that all charge carriers are effective, however oxide radicals play a key role during the process of photocatalysis. Photodegradation of pentachlorophenol in the presence of other phenolic pollutants indicates that BiSbO₄/BiSbS₃/CNHs can be utilized for degradation of other phenolic compounds. Further DFT studies are performed to know degradation behavior of pollutant as well as electrochemical measurements are also executed to illuminate the electrochemical behavior of all photocatalysts for supercapacitor applications.