Carbon dot/NiAl-layered double hydroxide hybrid material: facile synthesis, intrinsic peroxidase-like catalytic activity and its application

A novel carbon dot/NiAl-layered double hydroxide (C-dot/NiAl-LDH) hybrid material is successfully prepared through electrostatic self-assembly of positively charged NiAl-LDH nanoplates (3.74 +/- 0.3 mV) and negatively charged C-dots (-5.09 +/- 0.5 mV). The morphology, structure, composition and fluorescence properties of the hybrid material are characterized by different techniques, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and fluorescence spectroscopy. Moreover, C-dot/NiAl-LDH exhibits intrinsic peroxidase-like activity, which shows enhanced catalytic activities compared with C-dots and NiAl-LDH. The hybrid material facilitates the electron transfer between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2, which oxidizes TMB to form a blue product. On the basis of the peroxidase-like activity of C-dot/NiAl-LDH, the hybrid material can employ colorimetric detection of H2O2 with a lower detection limit of 0.11 mu M. The hybrid material also shows better stability than horseradish peroxidase (HRP) when exposed to solutions with different organic solvents and temperatures. The proposed method is successfully applied for the determination of H2O2 in milk samples.