DOI: https://doi.org/10.9767/bcrec.20350

S-scheme g-C3N4/PVA Heterojunction with Enhanced Photocatalytic Reduction of Aqueous Cr(VI) and Mechanism

1Metrology & Test, Shandong Special Equipment Inspection and Testing Group，25000, Jinan, Shandong, China

2School of Materials and Chemical Engineering, Xuzhou University of Technology, 221018, Xuzhou, China

3School of Chemistry and Environmental Science, Yili Normal University, 835000, Yining, China

4 School of Materials and Chemical Engineering, Xuzhou University of Technology, No.2, Lishui Road, Yunlong District, Xuzhou, 221018, China

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Received: 9 Feb 2025; Revised: 25 Mar 2025; Accepted: 26 Mar 2025; Available online: 27 Mar 2025; Published: 30 Aug 2025.
Editor(s): Istadi Istadi
Open Access Copyright (c) 2025 by Authors, Published by BCREC Publishing Group
Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
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Abstract

Bulk g-C3N4 was synthesized using melamine as a precursor through thermal polymerization followed by high-temperature quenching. Subsequently, a g-C3N4/PVA heterojunction featuring evenly dispersed PVA on its surface was fabricated via in-situ hydrothermal synthesis. The impact of hydrothermal temperature and PVA concentration on the light absorption, bandgap energy, specific surface area, and charge carrier transport characteristics of g-C3N4/PVA were explored. Experimental findings indicate that PVA modification reduces nitrogen-vacancy defects in the g-C3N4/PVA heterojunction, thereby enhancing its visible-light photocatalytic activity compared to bulk g-C3N4. Specifically, g-C3N4/PVA-3 exhibits a 2.93-fold higher reaction rate for Cr(VI) photocatalytic reduction under visible light (0.017 min–1) than bulk g-C3N4 (0.0058 min–1), with a TOF of 0.0079 h–1. Electrochemical tests confirm that the enhanced activity arises from improved light-induced charge transfer and separation efficiency. Based on Mott-Schottky analysis and the identification of •OH and •O2– as reactive species, a mechanism for Cr(VI) reduction by S-scheme g-C3N4/PVA heterojunctions is proposed. This study presents an economically viable and efficient method for developing high-performance conjugated polymer-modified photocatalysts. Copyright © 2025 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

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Keywords: Graphitic carbon nitride; Polyvinyl alcohol; Photogenerated carriers; S-scheme heterojunction; hexavalent chrome
Funding: Xuzhou University of Technology under contract Innovation and Entrepreneurship Projects for College Students (xcx2024002)

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