Monodispersed Ni active sites anchored on N-doped porous carbon nanosheets as high-efficiency electrocatalyst for hydrogen peroxide sensing

Highlights: • A facile MOFs route is developed to fabricate Ni@N–PCN hybrids with abundant mesopores. • Ni active sites was dispersed on N–PCN with ultrahigh dispersion degree. • A novel and efficient H₂O₂ electrochemical sensing platform was successfully developed. Metal active species combined with N-doped porous carbon nanosheets usually own excellent electrochemical activity and sensing performance owing to its unique microstructure and composition. In this work, monodispersed Ni active sites anchored on N-doped porous carbon nanosheets (Ni@N–PCN) were facilely prepared via rational metal-organic frameworks (MOFs) route. Firstly, zeolitic imidazolate frameworks-8 (ZIF-8) was in situ grown on physically-exfoliated graphene nanosheets (GN) with homogeneous sandwich-like structure (ZIF-8@GN). Secondly, nickel bonded ZIF-8@GN hybrids (Ni/ZIF-8@GN) were obtained by ionic exchange reaction, and then transformed into Ni@N–PCN by high-temperature pyrolysis. Benefiting from the monodispersed Ni active sites and highly reactive N-doped porous carbon nanosheets (N–PCN), the as-prepared Ni@N–PCN hybrids displayed superior catalytic performance toward hydrogen peroxide (H₂O₂) sensing. As a result, a highly sensitive electrochemical sensing platform for H₂O₂ was fabricated with low detection limit (0.032 μM), wide detection linearity (0.2–2332.8 μM), and high sensitivity (6085 μA cm⁻² mM⁻¹). Besides, the as-developed electrochemical sensing platform was successfully applied to detect H₂O₂ contents in biological medicine and food specimens with satisfied results. This study will provide effective guidance for the preparation of novel metal/N-doped carbon nanomaterials and establishment of high-performance electrochemical sensors.