In situ analysis of oxygen vacancy modified TiO2-Ov/g-C3N4 S-scheme heterojunction by 2D-PCIS spectroscopy for efficient synergistic photocatalytic degradation of naphthalene in water

Xiangyu Xiao; Suhua Zhai; Jiayiwen Wang; Muqun Wang; Min Huang; Ye Tao; Hongxiao Wang; Jianhua Xiong; ChuJian Wang; Yu Liang

doi:10.1016/j.envres.2025.122231

In situ analysis of oxygen vacancy modified TiO₂-O_v/g-C₃N₄ S-scheme heterojunction by 2D-PCIS spectroscopy for efficient synergistic photocatalytic degradation of naphthalene in water

Environ Res. 2025 Jun 25:122231. doi: 10.1016/j.envres.2025.122231. Online ahead of print.

Authors

Xiangyu Xiao¹, Suhua Zhai¹, Jiayiwen Wang¹, Muqun Wang², Min Huang³, Ye Tao¹, Hongxiao Wang¹, Jianhua Xiong⁴, ChuJian Wang⁵, Yu Liang⁶

Affiliations

¹ State Key Laboratory of Featured Metal Materials and Lif-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China.
² State Key Laboratory of Featured Metal Materials and Lif-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China. Electronic address: wangmq1108@163.com.
³ State Key Laboratory of Featured Metal Materials and Lif-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Bossco Environmental Protection Technology Co., Ltd., Nanning 530007, China.
⁴ State Key Laboratory of Featured Metal Materials and Lif-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi Bossco Environmental Protection Technology Co., Ltd., Nanning 530007, China. Electronic address: happybear99@126.com.
⁵ State Key Laboratory of Featured Metal Materials and Lif-cycle Safety for Composite Structures, School of Civil Engineering and Architecture, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Guangxi GuiLong Expressway Co., Ltd, Nanning 530007, China.
⁶ School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China. Electronic address: 416789026@qq.com.

PMID: 40578743
DOI: 10.1016/j.envres.2025.122231

Abstract

The S-scheme heterojunction notably improves the separation and transport of photogenerated carriers due to its distinctive charge transfer mechanism and structural advantages. In this study, TiO₂ was synthesized in situ on g-C₃N₄ using a hydrothermal method, followed by calcination to introduce oxygen vacancies and construct the S-scheme heterojunction photocatalyst (TCN). Experimental results showed that the optimal performance was achieved with a TiO₂-O_v content of 30%, where the TCN-30 catalyst degraded over 82.44% of naphthalene (Nap) within 180 minutes. Electron spin resonance (ESR) analysis confirmed the presence of many oxygen vacancy defects in TCN-30, as well as the generation of reactive oxygen species (ROS) during the experimental process, which played a key role in enhancing Nap degradation. Subsequently, a series of photoelectrochemical tests were conducted to demonstrate the excellent synergistic effect between oxygen vacancies and the strategy of constructing heterojunctions. Additionally, density functional theory (DFT) calculations helped clarify the working mechanism of the TCN S-scheme heterojunction and revealed its structure-activity relationship in photocatalytic applications. This study offers a theoretical foundation and technical guidance for the future design of photocatalysts tailored to specific functional needs.

Keywords: 2D-PCIS; Naphthalene degradation; S-scheme heterojunction; TiO(2)-O(v); g-C(3)N(4).