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Multifunctional cellulosic paper based on quaternized chitosan and gold nanoparticle–reduced graphene oxide via electrostatic self-assembly

The surface of a negatively charged paper fiber was coated with quaternized chitosan (QCS) by electrostatic self-assembly to form a homogeneous positive coating due to the highly positive charge and excellent film-forming properties of QCS. Gold chloride acid acted as a precursor to prepare gold nanoparticles (AuNP) on a graphene oxide (GO) sheet. Then, this negatively charged AuNP-loaded graphene oxide sheet was directly absorbed by QCS on the surface of fibers via further electrostatic self-assembly in water. Finally, AuNP–reduced graphene oxide/QCS/cellulose composite paper (AuNP–rGO/QCS/cellulose) was fabricated by a papermaking process, following reduction by hydrogen iodide vapor. The XRD, Raman spectra, XPS and FE-SEM results of the composite papers showed that the electrostatic self-assembly caused the graphene oxide sheets to tightly wrap the paper fibers, and that the graphene oxide was reduced, thus being beneficial to the formation of a superior graphene conductive network. Notably, AuNP–rGO/QCS/cellulose composite paper possessed a conductivity of 853.4 S m−1, which is the highest among the reported conducted graphene-based cellulosic paper, to the best of our knowledge. Besides, this composite paper also presented an excellent performance in photothermal conversion and catalysis of nitrophenol reduction. This type of paper may have promising applications in electric devices, sensors and catalysts.