A large-nanosphere/small-nanosphere (cellulose/silver) antibacterial composite with prominent catalytic properties for the degradation of p-nitrophenol

A well-designed spherical-nanocellulose (SNC)/silver-nanoparticle (AgNP) composite (SNC-AgNP) with a novel structure, a conjugate of large nanospheres (SNC, mean particle size 41 ± 9.7 nm) and small nanospheres (AgNPs, mean particle size 12 ± 6.3 nm), was prepared by the reduction of silver nitrate on plant-derived cellulose. The large nanospheres not only acted as a reducing agent, but more importantly, as a unique nano-spherical surface support, resulting in good dispersion of the small nanospheres. Thanks to this novel structure, the SNC-AgNPs possessed high antibacterial activity against the model microbes E. coli and S. aureus, and excellent catalytic properties for the degradation of p-nitrophenol. Notably, the catalytic rate constant (kapp = 1.6024 ± 0.0265 min−1) and catalytic activity factor (k = 5287.8 ± 644 min−1 g−1) of the SNC-AgNPs surpassed those of all cellulose-based Ag catalysts and most non-cellulose-based Ag catalysts. Moreover, the preparation of the SNC-AgNPs was high efficient, due to the high surface hydroxyl density of the SNC contributed from the cellulose II crystal structure, nano-spherical morphology, and low polymerization degree. Additionally, the thermal stability of the SNC-AgNPs was higher than most cellulose/Ag composite.