Environmental Applications of Single-Atom Nanozymes: Recent Developments and Future Directions

Abstract

Single-atom nanozymes (SANs) are a new class of artificial enzymes that feature isolated metal atoms anchored to tailored supports. This precise atomic dispersion provides maximum active site utilization while preventing aggregation and leaching, offering enhanced stability and recyclability over traditional nanozymes. This review systematically examines recent advances in the development of SANs for environmental applications, focusing on both pollutant detection and remediation. The review begins with a critical evaluation of synthesis methods of SANs, including pyrolysis, wet chemical, atomic layer deposition, and coordination templating approaches using both carbonaceous and non‑carbon supports. Subsequent sections examine the structure-activity relationships governing SANs and describe the factors that modulate their enzyme-like behaviors. Particular emphasis is placed on diverse catalytic properties, with attention to activity-tuning strategies such as heteroatom doping, microenvironmental engineering, and spin-state modulation. Next, the review assesses SANs-based detection platforms, such as colorimetric, fluorescent, electrochemical, and photoelectrochemical systems for monitoring and remediating diverse pollutants. This review critically evaluates current limitations of SANs and outlines strategies for their advancement. Structurally tunable active centers provide unique opportunities to construct dual-, tri-, and multi-enzyme systems with enhanced catalytic versatility. Density functional theory emerges as indispensable for rational design, enabling computation-guided active site engineering and elucidation of structure-activity relationships. Future research directions include tandem or bimetallic SANs for multielectron redox catalysis and integrated microdevices combining real-time detection with catalytic mineralization. Particular emphasis is placed on applications where SANs surpass conventional nanozymes or enzymes, thereby establishing design principles for next-generation, multifunctional catalytic platforms.