Enhanced photocatalytic degradation of Ponceau S Red dye on the novel hetero-system Fe 2 O 3 /WO 3 under solar light irradiation

Using the hetero-junction Fe 2 O 3 /WO 3 , a significant rate of photocatalytic activity was obtained for the degradation of Ponceau S Red dye (PSR) under solar irradiation. The mass ratio of Fe 2 O 3 / WO 3 was studied. Similarly, the experimental conditions leading to the total degradation of Ponceau S Red dye were optimized. The physical and optical properties of both semiconductors Fe 2 O 3 and WO 3 were correlated with the photo-electrochemical characterization to establish the energy diagram of the hetero-junction Fe 2 O 3 /WO 3 /electrolyte. The XRD, UV–visible and BET analyses were performed for both prepared compounds. Fe 2 O 3 and WO 3 have the band gap values of 2.18 and 2.66 eV, respectively and their optical transition is directly allowed. The flat band potentials, determined from the capacitance −2 – potential (C −2 –E) plots are found to be − 0.16 and 0.47 V SCE , respectively. The absorption of visible light produces a transfer of electrons from the conduction band of Fe 2 O 3 (− 0.61 V SCE ) toward low trapping of WO 3 –CB energy sites (0.04 V SCE ), which promotes the separation of charge carriers and therefore accelerates the PSR degradation. Under solar light illumination and the following conditions: pH ∼ 8, T ∼ 25 °C, and a catalyst dose of 1 mg/mL, total degradation of 10 mg/L of PSR is obtained. The chemical oxygen demand test confirms that most of Ponceau S Red dye was completely mineralized by photocatalytic process.