LU Yizhong，LIU Wendong，JIANG Yuanyuan

School of Materials Science and Engineering， University of Jinan， Jinan 250022， China

Abstract

Significance Nanozymes are nanomaterials with enzymatic properties that can catalyze substrate transformation under physiological conditions and exhibit reaction kinetics similar to natural enzymes. However, their widespread application is hindered by slow catalytic kinetics and low efficiency. Moreover, the unclear catalytic active sites constrain our understanding of their catalytic mechanism. As a result, constructing multifunctional nanozymes with well-defined active sites and high catalytic performance remains a significant challenge. Single-atom catalysts (SACs) mimic the catalytic center structure and activity of natural metalloproteases and are considered potential substitutes for natural metalloenzymes. The metal active sites of SACs are uniform, and their coordination environment is controllable, enabling the maximum utilization of metal atoms. This provides an ideal model for studying the structure-performance relationship. Cobalt-based single-atom catalysts (Co-SACs) exhibit outstanding performance in chemical and biological reactions. Exploring their catalytic performance across various reactions and evaluating their potential for large-scale industrialization is crucial for the advancement of related fields. Such efforts uncover the application value of nanozymes and provide innovative solutions for real-world production challenges.

Progress The oxidase-like activities of Co-SACs are classified into multiple functional types based on their catalytic substrates, primarily including aromatic amine oxidase-like activity, lactate oxidase-like activity, siloxane oxidase-like activity, reduced nicotinamide adenine dinucleotide (NADH) oxidase-like activity, and laccase-like activity. Further investigations into their modulation strategies reveal that performance regulation can be achieved through precise control of coordination numbers, directional heteroatom doping， construction of cobalt-transition metal synergistic effects, and optimization of metal-support interfacial interactions. Owing to their well-defined atomic-level structures and tunable coordination microenvironments, Co-SACs demonstrate remarkable advantages in advanced applications such as biosensing, tumor therapy, and organic synthesis.

Conclusions and Prospects Despite great progress, the future development of Co-SACs faces both challenges and opportunities. Future research should focus on optimizing cobalt active site loading and stability, as current limitations in these aspects restrict catalytic performance and may lead to particle aggregation. To address this, mild non-calcination strategies and functionalized support should be explored to enhance loading efficiency and stability, thereby facilitating large-scale synthesis. Building upon prior experience in precursor selection and condition optimization, engineering approaches for industrial-scale production and green synthesis methods can be developed. Additionally, it is crucial to improve catalytic selectivity and study the reaction mechanism. Future research should combine theoretical and experimental approaches to analyze factors influencing selectivity, ultimately establishing quantitative structure-activity models for precise catalyst design.