Application of Ag@g-C3N4/TiO2 cotton fabric flexible substrate with dual functionality: Photocatalytic reusability and SERS signal amplification for food safety detection

Utilizing hydrothermal synthesis, TiO2 and g-C3N4 were grown on cotton fabric. Subsequently, Ag NPs were uniformly deposited on their surfaces to produce a Ag@g-C3N4/TiO2 cotton fabric substrate (AGTC) with dual-functionalilites of photocatalytic reusability and SERS signal amplification. The introduction of TiO2 and g-C3N4 nanocomposites significantly enhances the SERS signal on the AGTC substrate for malachite green (MG) detection. The SERS signal on the AGTC substrate is 2.28 times stronger than that on the bare silver-modified cotton fabric, with a reduced detection limit of 6.74 × 10−13 M. Additionally, the Local Surface Plasmon Resonance (LSPR) effect induced by Ag NPs facilitates electron transfer among substrate components, markedly enhancing photocatalytic capability for degrading organic pollutants under visible light. Consequently, under visible light, the substrate rapidly degrades pollutants and reverts to a reusable state. Experimental results demonstrate the substrate's capability to continuously detect various concentrations and types of target substances, while maintaining high sensitivity. Leveraging the flexibility of cotton fabric, convenient wipe detection and self-cleaning experiments were conducted on the surfaces of different fish species, validating AGTC's outstanding sensitivity in real sample analysis. Therefore, as a flexible and reusable SERS substrate, AGTC exhibits broad potential applications in both SERS detection and photocatalytic degradation of pollutants.