Repurposing lignin to generate functional afterglow paper

Lignin is a significant byproduct from the pulp and paper industry. However, the conversion of lignin to a resource with added value is plagued by expensive processing. Here we report that the syringyl units (S) of sodium lignosulfonate (LS) exhibit phosphorescence in water with a lifetime of ∼2 ms and the lifetime can be prolonged up to ∼618 ms by encapsulation in Ca 3 (PO 4 ) 2 due to the formation of H-type dimers of the S units (LS@Ca 3 (PO 4 ) 2 ). Motivated by this, we develop afterglow paper through the in situ generation of LS@Ca 3 (PO 4 ) 2 in the paper matrix. The afterglow emission of the paper is sensitive to H 2 O 2 , enabling its application as a sensor for liquid/vapor H 2 O 2 . Moreover, the afterglow paper is shown to be suitable for use in anti-counterfeiting applications, enabling the development of a more sustainable pulp and paper industry.