Fabrication of a novel reusable nanozyme by immobilizing Co-doped carbon dots on nanocellulose aerogels for efficient dyes degradation

초록

Carbon dot-based nanozymes have gained significant attention, but their application in dye degradation remains limited due to low activity and challenges in recovery and reuse. To overcome these limitations, high peroxidaseactive Co-doped carbon dots (CoCDs) with surface amines were synthesized via hydrothermal method and immobilized onto TEMPO-oxidized cellulose nanofibrils (TOCNF) aerogels using EDC/NHS coupling. For the first time, this study investigates the dye degradation efficiency of CDs nanozyme. CoCDs with 1.456 % Co content exhibited excellent peroxidase-like activity with favorable kinetics (Km = 1.746 mM, Vmax = 22.05 x 10- 8 Ms- 1 for TMB and Km = 1.542 mM, Vmax = 23.54 x 10- 8 Ms- 1 for H2O2). The immobilized CoCDs enhanced the structural stability, and shape recovery of aerogels, even after multiple compressions. CoCDs/TOCNF aerogel with maximum CoCDs (114.7 mg/g) exhibited superior degradation efficiency for various dyes, including methyl orange (MO), methylene blue (MB), and rhodamine B (RhB), with rate constants of 12.7 x 10-3, 17.4 x 10-3, and 12.2 x 10-3 min- 1, respectively. Mechanistic studies revealed the major role of hydroxyl radicals in dye degradation. The aerogels exhibited exceptional recyclability with all dyes. This stable and recyclable nanozyme with high catalytic activity presents a promising avenue for environmental remediation.

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