Recycling hot-water extractions of lignocellulosic biomass in bio-refinery for synthesis of carbon nanoparticles with amplified luminescence and its application in temperature sensing

Fluorescent carbon dots (CDs) with amplified photoluminescence (PL) intensity were synthesized using recycled hot-water extraction wastes of lignocellulosic biomass according to a bio-refinery concept without carbonization of the entire biomass. The recycled waste liquid was obtained by pre-extracting biomass with pressurized hot-water under 120–180 °C for 30 and 60 min. CDs with controlled N-doping were obtained by a hydrothermal carbonization strategy of the pre-extraction liquid at 220 °C for 5 h. The main chemical component of pre-extraction hydrolysates was analyzed by high-performance liquid chromatography (HPLC). The effects of hydrolyzed sugars and other heteroatom-containing extracts on fluorescence of CDs were investigated by measuring the PL performance. The superior biomass-based CDs exhibited tunable quantum yields (QYs) of 6.2 %–11.8 % with hot-water extractions as precursor without carbonization destruction of the entire biomass. CDs with higher QYs could serve as an effective luminescent sensing platform for probes, temperature sensing, and anti-counterfeit applications.