Iron Phosphide Aerogel Applied as Nanozymes for Sensitive Colorimetric Detection of H ₂ O ₂

ABSTRACT Nanozymes represent a promising alternative to natural enzymes. However, their scalability is hampered by complex syntheses and expensive materials. Herein, we synthesized a kind of nanoscale iron phosphide (FeP) aerogel by a facile one‐step reduction method, which exhibits intrinsic peroxidase‐mimicking activity. A remarkably high affinity for H 2 O 2 , with a Michaelis‐Menten constant (K m = 0.096 mM) approximately 38‐fold lower than that of natural horseradish peroxidase (HRP, K m = 3.7 mM) was clearly demonstrated. Benefited from this excellent catalytic performance, a portable colorimetric sensor for H 2 O 2 was constructed. The sensor achieves accurate detection within a wide linear range of 1 µM–1 mM, a low detection limit of 0.3 µM (S/N = 3), and a high catalytic stability of over 15 days. This work not only further advances the utilization of aerogels in nanozyme design but also highlights the potential of iron‐based nanozymes in constructing inexpensive and portable biosensing platforms.