Defect-Rich CoFe-Layered Double Hydroxides as Superior Peroxidase-like Nanozymes for the Detection of Ascorbic Acid

The development of artificial enzymes with superior catalytic properties to natural enzymes has been a long-standing goal of chemists. Herein, defect-rich CoFe-layered double hydroxides (d-CoFe-LDHs) nanosheets are developed and used as superior peroxidase-like nanozymes for the detection of ascorbic acid (AA). The d-CoFe-LDHs with an average thickness of ∼3 nm and a lateral size of ∼20 nm are synthesized through rapid nucleation in a colloid mill, which exhibited abundant unsaturated sites (oxygen vacancies and cobalt vacancies). Impressively, d-CoFe-LDHs exhibited excellent peroxidase-mimicking performance with strong substrate affinity and robustness in a wide pH range. Density functional theory calculations show that d-CoFe-LDHs have lower H₂O₂ adsorption energy, which promotes the decomposition of H₂O₂, thereby improving the catalytic activity. The chromogenic system of d-CoFe-LDHs and 3,3',5,5'-tetramethylbenzidine can be used to accurately detect the content of AA, and the detection limit is about 3.6 μM. This study opens up a new approach for the construction of highly active defective LDH peroxidases for the detection of biomolecules.