Xylan-based ratiometric fluorescence carbon dots composite with delignified wood for highly efficient water purification and photothermal conversion

Herein, a novel xylan derived carbon dots (XMR-CDs) used as mercury ion (Hg2+) ratiometric fluorescence sensor via amidation reaction were firstly prepared. And by impregnating 0D XMR-CDs into 3D balsa delignified wood (DW) network for construction porous fluorescent wood for simultaneous detection and adsorption of Hg2+ (XMR-CDs-DW-Hg2+) for water purification. XMR-CDs exhibited rapid fluorescene response time and low detection limits (LOQs) of 1.7 nM towarded Hg2+ with F580 nm/F436 nm = 3.39+0.02[Hg2+], R2 = 0.9856. And the recoveries of XMR-CDs detection Hg2+ in real water and food samples were in the range of 97.8–104.8%. Adsorption experiments confirmed that XMR-CDs-DW displayed adsorption capacity of Hg2+ over 291.4 mg g-1. Further, XMR-CDs-DW-Hg2+ was covered into a suitable material (XMR-CDs-DW-HgS) by using in-situ sulfurization method for photothermal conversion, which exhibiting a excellent photothermal conversion rate of 3.3895 kg m-2 h-1. Importanly, sea water purified by XMR-CDs-DW-HgS could also be utilized for real-time to cultivate plant and zebrafish, which proving the feasibility and potential of solar desalination–cultivation integrated system. This work highlights a strategy for Hg2+ detection, adsorption and removal, and reuse hazardous waste for photothermal evaporation, which providing practical applications for water purification and environmental protection.