Citation: Khan, A.A.; Marchiori, L.; Ferreira-Neto, E.P.; Wender, H.; Parveen, R.; Muneeb, M.; Mattos, B.O.; Rodrigues-Filho, U.P.; Ribeiro, S.J.L.; Ullah, S. Enhanced Photoredox Activity of BiVO 4 /Prussian Blue Nanocomposites for Efficient Pollutant Removal from Aqueous Media under Low-Cost LEDs Illumination. Catalysts 2022, 12, 1612. https://doi.org/10.3390/ catal12121612 Academic Editors: Gassan Hodaifa, Rafael Borja and Mha Albqmi Received: 19 October 2022 Accepted: 4 December 2022 Published: 8 December 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). catalysts Article Enhanced Photoredox Activity of BiVO 4 /Prussian Blue Nanocomposites for Efficient Pollutant Removal from Aqueous Media under Low-Cost LEDs Illumination Abrar Ali Khan 1 , Leonardo Marchiori 2 , Elias Paiva Ferreira-Neto 3 , Heberton Wender 4 , Rashida Parveen 5 , Mohammad Muneeb 1 , Bianca Oliveira Mattos 6 , Ubirajara Pereira Rodrigues-Filho 6 , Sidney José Lima Ribeiro 2 and Sajjad Ullah 1, * 1 Institute of Chemical Sciences, University of Peshawar, Peshawar P.O. Box 25120, Pakistan 2 Institute of Chemistry, São Paulo State University (UNESP), Araraquara 14800-060, SP, Brazil 3 Department of Chemistry, Federal University of Santa Catarina (UFSC), Florianópolis 88040-900, SC, Brazil 4 Nano&Photon Research Group, Laboratory of Nanomaterials and Applied Nanotechnology, Institute of Physics, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, MS, Brazil 5 Government Girls Degree College Dabgari, Peshawar 25000, KP, Pakistan 6 Institute of Chemistry of São Carlos, University of São Paulo, São Carlos 13560-970, SP, Brazil * Correspondence: sajjadullah@uop.edu.pk Abstract: Bismuth vanadate (BiVO 4 , BV) is a widely explored photocatalyst for photo(electro)chemical applications, but its full photocatalytic potential is hindered by the fast recombination and low mobil- ity of photogenerated charge carriers. Herein, we propose the photodeposition of different amounts of Prussian blue (PB) cocatalysts on the surface of monoclinic BV to obtain BV-PB composite photo- catalysts with increased photoactivity. The as-prepared BV and BV-PB composites were characterized by an array of analytic techniques such scanning eletron microscopy (SEM), transmission eletron mi- croscopy (TEM), X-day diffraction (XRD), and spectroscopic techniques including Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photoluminescence (PL), and Raman spectroscopy. The addition of PB not only increases the absorption of visible light, as indicated by DRS, but also improves the charge carri- ers’ transfer across the photocatalysts/solution interface and hence reduces electron-hole (e - -h + ) recombination, as confirmed by EIS and PL measurements. Resultantly, the BV-PB composite photo- catalysts with optimum PB loading exhibited enhanced Cr(VI) photoreduction efficiency as compared to pristine BV under visible light illumination from low-power blue light-emitting diodes (LEDs), thanks to the cocatalyst role of PB which mediates the transfer of photoexcited conduction band (CB) electrons from BV to Cr(VI) species in solution. Moreover, as compared to pristine BV and BV + H 2 O 2 , a drastic increase in the methylene blue (MB) photo-oxidation efficiency was observed for BV-PB in the presence of a minute quantity of H 2 O 2 due to a synergic effect between the photo- catalytic and Fenton-like processes. While pure BV photodegraded around 70% of MB dye within 120 min, the BV-PB/H 2 O 2 and BV/H 2 O 2 system could degrade almost 100% of the dye within 20 min (k obs. = 0.375 min -1 ) and 40 min (k obs. = 0.055 min -1 ), respectively. The practical approach employed in this work may pioneer new prospects for synthesizing new BV-based photocatalytic systems with low production costs and high photoredox efficiencies. Keywords: photocatalysis; photo-fenton; BiVO 4 ; Prussian blue; cocatalyst; water purification 1. Introduction With increasing industrialization and anthropogenic activities across the globe, fresh- water bodies have been adversely affected by the uncontrolled contamination with many toxic substances, including both organic (dyes, pharmaceuticals, pesticides, etc.,) and in- organic contaminants (heavy metal ions). The presence of these toxic dyes and especially Catalysts 2022, 12, 1612. https://doi.org/10.3390/catal12121612 https://www.mdpi.com/journal/catalysts