Hierarchically porous graphitic carbon membrane with homogeneously encapsulated metallic nanoparticles as monolith electrodes for high-performance electrocatalysis and sensing.

We report a facile and versatile method to homogeneously deposit monolith membrane with uniform, high density of metallic nanoparticles via a "ship-in-a-bottle" strategy. Polyamidoamine (PAMAM) dendrimer, an excellent matrix for complexing with metal ions, is pre-infiltrated and applied as the directing agent for in-situ confined-formation of palladium nanoparticles (PdNPs) inside the mesopores. Efficiency of this method is demonstrated to prepare homogeneous PdNPs-deposited hierarchically porous graphitic carbon (HPGC) membrane with uniform metallic particle size (2.0-2.5 nm) and high palladium loading (~34.4 wt%). Taking advantages of fast molecule diffusion rate in hierarchically porous structure and high conductivity of graphitic carbon substance, the PdNPs-dispersed HPGC membranes are applied as monolith electrodes for electrochemical applications. The PdNPs-deposited HPGC membrane electrode exhibits excellent electrocatalytic activity toward the catalytic oxidation of dopamine, uric acid and ascorbic acid, as well as high sensitivity and selectivity in simultaneous determination of these compounds in real serum samples. The limit of detections for dopamine, uric acid and ascorbic acid are 1.3 × 10, 2.6 × 10 and 3.7 × 10 M, respectively, at least one order lower than that achieved on electrochemical sensors reported previously. This work provides a versatile method for efficient preparation and stabilization of monodisperse metallic NPs in diverse porous materials, leading to possible applications in devices, catalysis, and electrochemical sensing.