A g-C₃N₄/Ti₃C₂@EC fiber composite membrane: Mechanism of simultaneous photothermal degradation and fluorescent detection of hydrochloride tetracycline in wastewater

Antibiotic residues in aquatic environments severely threaten ecosystems and human health, necessitating rapid pollutant detection and removal. This study develops a novel g-C₃N₄/Ti₃C₂@ethyl cellulose nanofiber composite membrane (CT@EC), synthesized via electrostatic self-assembly and electrospinning, for photothermal degradation and fluorescence detection of tetracycline hydrochloride (TCH), as well as hydrogen production. The 3D porous structure of CT@EC enhances mass transfer and exposes active catalytic sites, while the g-C₃N₄/Ti₃C₂ heterojunction forms a built-in electric field (BIEF) that is 2.11 times stronger than that of g-C₃N₄@EC, promoting efficient charge carrier separation. As demonstrated by the lower activation energy (E_a, 15.08 kJ/mol) and the negative Gibbs free energy change (ΔG^θ, −28.16 kJ/mol), CT@EC, with a high photothermal conversion efficiency (78.0 %) from Ti₃C₂, ultimately achieves 96.0 % TCH degradation after 160 min of illumination. Meanwhile, CT@EC exhibits outstanding hydrogen evolution (2528.1 μmol/g). Additionally, CT@EC serves as a fluorescence sensor for TCH detection based on the inner filter effect (IFE), integrated with a smartphone for real-time, quantitative detection in the 15–170 μM range, with a detection limit of 0.68 μM. This multifunctional membrane holds great potential for practical applications in environmental governance and hydrogen production.