ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Photo-electrocatalytic degradation of azo dye and evaluation of the electricity generation by using a visible light active CNT-TiO₂-BiOBr-Bi₂S₃ electrode

Malihe Asadpoor, Maryam Fakharzadeh, Seyed Esmail Fazljoo, Mehdi Ardjmand, Mehrdad Farhadian, Mohammadreza Omidkhah, and Ali Akbar Zinatizadeh

Department of Polymer and Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran

E-mail: malihe_asadpoor@yahoo.com

Received: 27 September 2024  Accepted: 19 March 2025

Abstract:

This study presents a promising technology for the degradation of azo dye (Acid black 172 (AB 172)) using a modified TiO₂ anode. CNT-TiO₂-BiOBr-Bi₂S₃ was synthesized and deposited on the anode electrode, and a graphite sheet was selected as the cathode in a photoelectrochemical oxidation process. The CNT-TiO₂-BiOBr-Bi₂S₃ composite photocatalyst significantly advances visible light-driven photocatalytic systems, outperforming conventional catalysts due to synergistic interactions among its components. The morphology, chemical composition, and optical properties of the CNT-TiO₂-BiOBr-Bi₂S₃ catalyst were investigated by XRD, FTIR, FESEM, EDX, PL, and UV–Vis analyses, respectively. The effects of the processing factors and their statistical optimization values were determined using response surface methodology. The results showed that increasing the light intensity and irradiation time enhanced the photoelectrochemical degradation of the azo dye. In contrast, increasing the dye concentration leads to a decrease in degradation efficiency and COD removal. The acidic medium is beneficial in improving the removal efficiency of AB 172. Complete removal of AB 172 was achieved under optimal degradation parameters, including pH = 4, an AB 172 concentration of 15 mg/L, an irradiation time of 7 h, and a light intensity of 500 lm. COD removal and current density were about 90% and 200 µA, respectively, under optimal conditions. The anode and cathode reusability were examined, showing that the photoelectrochemical process effectively degrades contaminants, even after four electrode reuse cycles. This study demonstrates the potential of using reusable CNT-TiO₂-BiOBr-Bi₂S₃ electrodes for visible light-responsive and sustainable water and wastewater treatment technology.

Keywords: Bionanoelectronics; Electrochemistry; Electrocatalysis; Photocatalysis; Supercapacitors; X-Ray Photoelectron Spectroscopy; Photoelectrochemical process; CNT-TiO2-BiOBr-Bi2S3 anode; Azo dye; Wastewater treatment; Nanocatalyst; Optimal degradation parameter

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04028-1

Chemical Papers 79 (6) 3739–3752 (2025)