Designing covalent organic frameworks membranes with a dual-mode acid sensing and exploration of photothermal...

As a new type of organic porous crystalline material connected with covalent bonds, covalent organic frameworks (COFs) have shown unique advantages in many fields. However, the preparation of COFs membrane that are easy to prepare and can be applied multiple times still is a challenge. Here, 2,5-Dimethoxybenzene-1,4-dicarboxaldehyde (Dma) and 4,4',4''-(1,3,5-Triazine-2,4,6-triyl) trianiline (TAPT) was used as a reactant and Dma-TAPT fiber membranes with good crystallinity and stability were prepared through electrospinning technology and solvothermal in-situ growth. The XRD, SEM, ¹³C NMR, IR, and XPS, etc. were used to characterize the structure of obtained membrane. The prepared membranes not only showed fluorescence detection for acid but also realize the visual detection via a portable smartphone. The density functional theory calculation and experimental results verified that the methoxy group provide site for the interaction with H⁺ in acid. Additionally, because of the increase of light absorption capacity the photothermal efficiency of COFs after acidification was improved by 17.4 % for the COFs before acidification. The research provides ideas for designing new sensitive and recyclable pH sensors.