Contribution of surface carboxyl of cellulose in the formation mechanism and interfacial catalysis activity of ZnO/cellulose nanocomposites

The morphology, structure, and dispersion of photocatalysts play important roles in tailoring the surface active sites, photocatalytic productivity, and light utilization efficiency. Cellulose has been widely used in supporting and dispersing ZnO catalysts. However, surface groups of cellulose were ignored as a factor governing ZnO morphology. This work aims to explore the effects of cellulose surface groups on the formation and properties of ZnO catalysts. The reactivity, electronegativity, ion adsorption, and dispersion of the cellulose are improved after the introduction of carboxyl groups, which is beneficial to observe the induction of cellulose surface charge on the growth of ZnO. The results indicate that the diameter, sheet number, and thickness of flower-like ZnO in porous ZnO/cellulose nanocomposites are increased with the enhancement of cellulose surface electronegativity. The ZnO/cellulose nanocomposites with surface carboxyl content of 1.63 mmol*g−1 and zeta potential of –52.6 mV (ZnO/TOCNF3) have the highest photocatalytic activities and recycling for MO degradation due to the exposure of the interfacial active sites and strong electrostatic adsorption between carboxyl and ZnO. These findings provide a green method to regulate the formation and properties of catalysts by adjusting the surface electronegativity of cellulose nanofibers.