Cobalt-decorated 3D hybrid nanozyme: A catalytic amplification platform with intrinsic oxidase-like activity

Highlights: : • Co@NCNTs/NC nanomaterial with enhanced intrinsic oxidase-like activity was designed and synthesized. • Confined growth strategy is utilized to regulate the formation of Co@NCNTs/NC to avoid the aggregation of nanoparticles. • The signal amplification platform is constructed by Co@NCNTs/NC due to the synergistic catalysis arising from the Co species and N-doped carbon architecture. • This work presents a new approach to construct a new kind of artificial enzyme for medical diagnostics and physiological research. -- Abstract: : Research about constructing multi-dimensional carbon nanomaterials is of great significance in electrocatalytic and sensing fields in order to integrate structural merits of each individual unit. Also, nanomaterials with enzyme-like activities are prospective candidates for artificial enzyme design and electrochemical application. Herein, we fabricate Co, N co-doped hierarchical hybrid (Co@NCNTs/NC) nanozyme, which integrates of both N-doped carbon nanotubes (NCNTs) and N-doped carbon sheets (NC). The three-dimensional (3D) porous carbon composite is prepared by thermal treatment of metal-organic framework (MOF) which was synthesized by growing of ZIF-67 on ZIF-L at room temperature. The obtained nanomaterial not only possesses an improved oxidase-like activity that can catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) in the absence of hydrogen peroxide (H₂O₂), but also constructs a signal amplification platform towards dopamine (DA) due to the synergistic catalysis of Co species and N-doped porous carbon architecture. The electrocatalytic performance for DA detection shows a broad linear range from 30 nM to 710 μM and a detection limit of 9 nM. The Co@NCNTs/NC/GCE is employed to practically detect DA in human serum and artificial cerebrospinal fluid (aCSF) samples with satisfactory results. The present work exhibits a great promising in colorimetric and electrochemical sensing fields and presents a new sight for the fabrication of MOF-derived nanozyme.