In situ green immobilization of palladium nanoparticles onto polydopamine-modified eggshell membrane for catalytic reduction of nitrophenols

4-Nitrophenol (4-NP) poses significant threats to both ecosystems and human health, making it essential and highly beneficial to take effective measures to mitigate its impact. Herein, eggshell membrane (ESM) with mussel-inspired polydopamine coatings (ESM-PDA) was constructed and utilized as a template for the immobilization of Pd NPs, resulting in ESM-PDA-Pd formation. The catalyst ESM-PDA-Pd exhibits exceptional performance in reducing 4-NP, and the TOF (turnover frequency) for ESM-PDA-Pd was determined to be 3.3 × 10−5 mmol·mg−1·min−1. Moreover, ESM-PDA-Pd demonstrates excellent catalytic activity in reducing other nitrophenols, including 2-nitrophenol (0.2196 min−1) and 2,4,6-nitrophenol (0.1177 min−1). Notably, the catalyst demonstrated brilliant recyclability, removing 92.4 % of 4-NP within 20 min after undergoing five consecutive runs. This underscores its potential for sustained and effective use in multiple cycles of nitrophenol reduction reactions. Furthermore, the measured Kapp in various water samples is as follows: ultrapure water (0.135 min−1) > tap water (0.109 min−1) > river water (0.083 min−1), indicating its significant potential for industrial applications.