A nanoflower-like polypyrrole-based cobalt-nickel sulfide hybrid heterostructures with electrons migration to boost overall water splitting.

The development of high-efficiency and cost-effective difunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are highly attractive to fulfill the practical water electrolysis. Herein, a novel low-cost difunctional cobalt-nickel sulfide (Co3S4/Ni3S2) flower-like heterostructures are purposely loaded on the surface of polypyrrole (PPy) nanosheets on nickel foam (NF) via feasible and efficient electrodeposition and hydrothermal tactics. The unique hierarchical architecture of the PPy nanosheets and strong electron interaction in the Co3S4/Ni3S2 nanohybrid effectively offer sufficient specific surface area and regulate electronic configuration for expediting the electrocatalytic process. The theoretical simulations also provide convincing proof that the interface of the Co3S4/Ni3S2 heterostructures supplies a lower energy pathway for water adsorption and dissociation, and the electrons migration that occurs when heterostructures emerge is probably the root of the result above. Consequently, the as-fabricated Co3S4/Ni3S2@PPy/NF exhibits outstanding electrochemical activity of HER and OER requiring low overpotentials of 63 mV and 207 mV to reach a current density of 10 mA cm-2 in the alkaline electrolyte, respectively. When equipped in a two-electrode electrolyzer, the Co3S4/Ni3S2@PPy/NF electrode couple displays a low voltage of only 1.52 V at 10 mA cm-2, indicating its potential application in the field of the water electrolysis.

Novel L-lactic acid biosensors based on conducting polypyrrole-block copolymer nanoparticles.

The development of advanced nanomaterials for the highly efficient electrical detection of biological species has attracted great attention. Here, novel polypyrrole-Pluronic F127 nanoparticles (PPy-F127 NPs) with conducting and biocompatibility properties were synthesized and used to construct a L-lactic acid biosensor that could be applied in biochemical assays. The PPy-F127 NPs were characterized by transmission electron microscopy (TEM), elemental analysis and UV-vis spectroscopy. Lactate oxidase (LOx) structure variation on the PPy-F127 NPs was investigated by circular dichroism (CD). The cyclic voltammetric results indicated that LOx immobilized on the PPy-F127 NPs exhibited direct electron transfer reaction with a formal potential value (E(0)') of 0.154 V vs. SCE. Moreover, the biosensor had good electrocatalytic activity toward L-lactic acid with a wide linear range (0.015-37.5 mM) and a low detection limit of 0.0088 mM. The regression equation was I (µA) = 0.02353c (mM) + 1.4135 (R(2) = 0.9939). The L-lactic acid biosensor had a good anti-interference property towards uric acid (UA), ascorbic acid (AA), glucose and cysteine. The idea and method provide a promising platform for the rapid development of biosensors that can be used in the detection of biological species.

Electrochemical immunosensor based on hyperbranched structure for carcinoembryonic antigen detection.

Sensitive determination of carcinoembryonic antigen (CEA) is very important in clinical research and diagnosis. Herein we report the design and synthesis of a new kind of immunosensor based on the benefits of hyperbranched structure. The hyperbranched polyester was grafted to the surface of indium tin oxides glass (ITO) electrode, and the grafting processes were characterized by attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). After CEA and horse radish peroxidase (HRP)-labeled antibody-conjugated AuNPs (HRP-Ab2-AuNPs) bioconjugates were immobilized on the surface of the hyperbranched structure-modified electrode, the optimized conditions of the above electrode were investigated. Moreover, the analytical performance of the proposed immunosensor showed a high sensitivity, a linear range from 0.01 to 80ng/mL with a low detection limit of 2.36pg/mL, and good selectivity for CEA. The designed immunoassay system holds great potential for ultrasensitive electrochemical biosensing of other analytes.