Enhanced photoelectrocatalytic degradation of diclofenac sodium using a system of Ag-BiVO4/BiOI anode and Ag-BiOI cathode

Abstract

We report the photoelectrocatalysis of diclofenac sodium using a reactor consisting of Ag-BiVO4/BiOI anode and Ag-BiOI cathode. The electrodes were prepared through electrodeposition on FTO glass and modified with Ag nanoparticles through photodeposition. The structural and morphological studies were carried out using XRD, SEM, and EDS which confirmed the successful preparation of the materials. The optical properties as observed with UV-DRS revealed that the electrodes were visible light active and incorporation of metallic Ag particles on the surface increased the absorption in the visible light region. Presence of p-n heterojunction in the anode led to decrease in the spontaneous recombination of photoexcited electron–hole pairs as seen in the photocurrent response. The results from photoelectrocatalytic degradation experiments revealed that replacing platinum sheet with Ag-BiOI as counter electrode resulted in higher (92%) and faster removal of diclofenac sodium as evident in the values of apparent rate constants. The reaction mechanism further revealed that efficiently separated photogenerated holes played a major role in the degradation of the pharmaceutical. The prepared electrodes showed good stability and impressive reusability. The reports from this study revealed that the dual photoelectrodes system has a great potential in treating pharmaceutical polluted wastewater using visible light irradiation.

Mo-BiVO4/Ca-BiVO4 Homojunction Nanostructure-Based Inverse Opals for Photoelectrocatalytic Pharmaceutical Degradation under Visible Light

“…Initial VLA photoelectrocatalytic tests were carried out on SA degradation in 0.1 M NaHCO 3 supporting electrolyte using Mo-BiVO 4 PC films (Supporting Information S2) under no bias potential, +0.5 and +1.0 V vs Ag/AgCl under visible and UV–vis illumination (Figure S11). A marked acceleration of SA photodegradation kinetics with an applied potential was observed, verifying its beneficial role in assisting photogenerated electron–hole separation . In addition, linear sweep voltammetry and photoelectrocatalytic SA degradation experiments were performed on thicker Mo-BiVO 4 PC films under visible light (Figure S12).…”

“…A marked acceleration of SA photodegradation kinetics with an applied potential was observed, verifying its beneficial role in assisting photogenerated electron−hole separation. 57 In addition, linear sweep voltammetry and photoelectrocatalytic SA degradation experiments were performed on thicker Mo-BiVO 4 PC films under visible light (Figure S12). An increase of the inverse opal film thickness resulted in the decrease of both photocurrent density and the SA kinetic constant, indicative of persistent electron transport limitations that depend on the films' morphology, similar to nanocrystalline Mo-BiVO 4 photoelectrodes for water splitting.…”

Bismuth Oxyhalide-Based Materials (BiOX: X = Cl, Br, I) and Their Application in Photoelectrocatalytic Degradation of Organic Pollutants in Water: A Review

“…In a typical three-electrode system, the working electrode (commonly FTO or ITO), the reference electrode and the counter electrode are placed in a reaction medium, usually a hydrolysis synthesis medium. ( Ye et al, 2015 ; Orimolade and Arotiba, 2022 ). A suitable potential difference is applied at a specific time (depending on the material), and the BiOX particles migrate to the electrode and deposit on its surface, covering it with a thin film.…”

“…In this way, a so-called Schottky barrier is formed which prevents the return of charge carriers from the metal back to the semiconductor, that is, the charge flow occurs unidirectionally ( Bai et al, 2015 ; Kumar et al, 2021 ). In this context, Orimolade and Arotiba, (2022) fabricated a functional BiOI photoelectrode decorated with Ag nanoparticles supported on FTO glass. By loading silver particles on the BiOI/FTO electrode, the photocurrent responses increased.…”

Peroxymonosulfate enhanced photoelectrocatalytic degradation of 17α-ethinyl estradiol

“…Advanced oxidation processes have emerged as a solution to such persistent compounds. More specifically, photoelectrocatalysis (PEC) has proven effective in removing a wide range of micropollutants by the efficient use of both light and electrical energy while overcoming the major drawbacks such as (i) the recombination of photogenerated electron-hole pairs that occurs in a conventional photocatalytic process and (ii) the higher energy demand of an anodic oxidation process [6]. PEC processes necessitate the immobilization of a photocatalyst on an electrode surface, eliminating the need for catalyst separation and regeneration at the end of the process.…”