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.