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AuPt alloy films with three-dimensional (3D) hierarchical pores consisting of interconnected dendrite walls were successfully fabricated by a strategy of cathodic codeposition utilizing the hydrogen bubble dynamic template. The foam films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Due to the special porous structure, the electronic property, and the assembly effect, the AuPt alloy foam films show superior electrocatalytic activity toward the electrooxidation of formic acid in acidic solution, and the prepared 3D porous AuPt alloy films also show high activity and long stability for the electrocatalytic oxidation of methanol, where synergistic effect plays an important role in addition to the electronic effect and assembly effect. These findings provide more insights into the AuPt bimetallic nanomaterials for electrocatalytic applications.

The 3D NiO hollow sphere/reduced graphene oxide (rGO) composite was synthesized according to the coordinating etching and precipitating process by using Cu 2 O nanosphere/graphene oxide (GO) composite as template. The morphology, structure, and composition of the materials were characterized by SEM, TEM, HRTEM, XPS, and Raman spectra, and the electrochemical properties were studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. Moreover, the electrochemical activity of the composite materials with different morphologies were also investigated, which indicating a better combination of the NiO hollow sphere and the rGO. Used as glucose sensing material, the 3D NiO hollow sphere/rGO composite modified electrode exhibits high sensitivity of ~2.04 mA mM −1 cm −2 , quick response time of less than 5 s, good stability, selectivity, and reproducibility. Its application for the detection of glucose in human blood serum sample shows acceptable recovery and R.S.D. values. The outstanding glucose sensing performance should be attributed to the unique 3D hierarchical porous superstructure of the composite, especially for its enhanced electron-transfer kinetic properties.Electrochemical biosensors have been extensively applied to detect biological substances via catalysis and recognition behaviors happening on the surface of electrodes in the fields of medicine, food, industry and environment 1-4 . The generation of electrochemical signal normally includes electrocatalytic reaction happening at the electrolyte/electrode interface, and the electron transfer inside the electrode 5,6 . Intimate correlation of sensing performance and the structural and electrocatalytic properties of electrodes has motivated great efforts to the design of new materials with superior electrocatalytic activity and electron-transfer kinetics to achieve rapid and sensitive response of electrochemical signal in biosensor 7,8 .Metal oxides play an important role in the miniaturization of glucose biosensor due to their inexpensive, good biocompatibility, and excellent electrocatalytic activity along with the controllability of the structure and morphology 9-11 . The effective application of metal oxides is prospective to break through the pivotal limitations of the costly enzymes since the typical glucose oxidase is intrinsically susceptible to the physical and chemical environments 1, 12-14 . Nanostructured metal oxides, such as zero-dimensional (0D) particles, 1D nanowires, 2D nanosheets, and some hollow structures have been widely studied as electrode materials for glucose biosensors with improved sensitivity, reproducibility, and stability. Nickel-based materials, such as NiO and Ni(OH) 2 have been extensively research as electrocatalyst for glucose due to its redox couple of Ni 3+ /Ni 2+ in the alkaline medium. However, the poor electronic conductivity of nickel-based materials at room temperature determines the inferior electron-transfer kinetics of the constructed electrodes, which significantly hinders ...

We report here a novel one-step electrochemical method to fabricate three-dimensional (3D) micro−nano hierarchical porous gold films (PGFs) by the surface rebuilding of smooth gold substrates in a blank solution of NaOH with square wave potential pulse. The potential is controlled such that it involves repeated gold oxidation−reduction and intensive hydrogen evolution, where the hydrogen gas bubbles function as a dynamic template to shape the assembly of the gold nanoparticles from the oxidation−reduction. Particularly, this method is green, convenient, and economical, which enables us to fabricate the 3D porous structure from the metal itself requiring neither Au(III) species and additives in solution nor post-treatment of template removal. The pore formation and evolution have been characterized by scanning electron microscopy. The as-prepared 3D PGF is multifunctional, for example, (i) high electrocatalytic activity toward the oxidation of some fuel/biomolecules like ethanol, glucose, and ascorbic acid; (ii) strong surface-enhanced Raman scattering effect with the merits of being stable and easily renewed; and (iii) interesting transition from superhydrophilicity to superhydrophobicity by decorating with a self-assembled thiol monolayer.