Study of the photoelectrochemical properties of a modified bismuth oxyiodide boron-doped diamond electrode

Chromium (VI) is a toxic metal present in water and difficult to remove. Among the environmental remediation methods, photoelectrocatalysis stands out for its low operating cost, high efficiency and sustainability. Due to its unique properties, boron-doped diamond (BDD) is considered a suitable electrode for electrocatalysis processes when modified with a semiconductor. BiOI presents a band-gap that allows it to be activated with visible light, and its p-type semiconducting nature makes it an optimal catalyst for reduction reactions. For this reason, this work presents the development of a BDD/BiOI photocathode using SILAR-spin coating method for its application in the photoelectroreduction of Cr(VI). The photoelectrochemical properties of the cathode are characterized by cyclic voltammetry, through the redox response of K3[Fe(CN)6] / K4[Fe(CN)6]·3H2O and the study of the photocurrent at oxidation and reduction potentials. In addition, the structure and morphology of BDD/BiOI were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Furthermore, the effectiveness of BDD/BiOI in Cr(VI) reduction assays in aqueous media at pH 1.5 is evaluated. SEM and XRD analyses reveal that the chemical identity of the BiOI synthesized by solvothermal crystallization is the same as the material on the BDD, in addition, it is demonstrated that the reaction kinetics corresponds to pseudo first order, except for the process under light incidence, where a different kinetic order is presumed for two time intervals. Finally, 100% photoelectrochemical reduction of Cr(VI) is achieved in 10 min under visible light incidence employing BDD/BiOI. The developed photocathode proves to be efficient for Cr(VI) reduction in aqueous medium under visible light incidence, with low energy cost and simple assembly method.

• Main Author: Soria Sánchez, Daniel Andrés (author)
• Format: article
• Published: 2023
• Subjects: Control de contaminación; fotoelectrocatálisis; electrodos; diamante dopado con boro; fotoelectroquímica
• Online Access: https://repositorio.puce.edu.ec/handle/123456789/21016