Pollutant removal from aqueous solutions and effective photocatalytic H2 generation by enhanced visible-light-driven S-scheme composite: Response surface methodology optimization and electron transfer pathways

This research introduces a photocatalytic method as a sustainable alternative to chemical processes for reducing hazardous pollutants in water and enhancing hydrogen generation. A novel 30 % FeCe/SiO2 S-scheme heterojunction photocatalyst was synthesized via an in-situ impregnation technique, optimizing the photodegradation of levofloxacin (LEF). Comprehensive analyses, including SEM, TEM, XPS, N2 adsorption–desorption, XRD, UV–vis DRS, EIS, Photocurrent, Mott Schottky, and PL, were conducted to investigate the photocatalyst’s chemical, morphological, and optical properties. The photocatalyst demonstrated enhanced physicochemical attributes, such as increased optical absorption, larger surface area, improved charge mobility, and extended excited state lifetime, leading to its superior photocatalytic activity in degrading LEF, cefixime, and tetracycline under ideal conditions. Scavenger tests and ESR data revealed that the active species h+, radical O2−, and radical OH played a collaborative role in the photocatalysis, with radical OH and radical O2− being more influential than h+. The study deduced a conjugated S-scheme charge transfer mechanism, which clarified the enhanced photocatalytic performance. The degradation pathways of LEF and its intermediates were determined through HPLC/MS analysis, achieving 69 % TOC mineralization. Additionally, the integration of a 30 wt% Fe2O3/CeO2 mixture into SiO2 significantly increased hydrogen production to 2.57 mmol/g·h, which is 27.5 times higher than unaltered SiO2. The study showcases the development of an S-scheme heterostructure photocatalyst, promising for water purification and hydrogen production applications.

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