Phase Transformation from Amorphous RuSx to Ru-RuS2 Hybrid Nanostructure for Efficient Water Splitting in Alkaline Media.

Ruthenium (Ru)-based materials, as a class of efficient hydrogen evolution reaction (HER) catalysts, play an important role in hydrogen generation by electrolysis of water in an alkaline solution for clean hydrogen energy. Hybrid nanostructure (HN) materials, which include two or more components with distinct functionality, show better performance than their individual materials, since HN materials can potentially integrate their advantages and overcome the weaknesses. However, it remains a challenge to construct Ru-based HN materials with desired crystal phases for enhanced HER performances. Herein, a series of new Ru-based HN materials (t-Ru-RuS2, S-Ru-RuS2, and T-Ru-RuS2) through phase engineering of nanomaterials (PEN) and chemical transformation are designed to achieve highly efficient HER properties. Owing to the plentiful formation of heterojunctions and amorphous/crystalline interfaces, the t-Ru-RuS2 HN delivers the most outstanding overpotential of 16 mV and owns a small Tafel slope of 29 mV dec-1 at a current density of 10 mA cm-2, which exceeds commercial Pt/C catalysts (34 mV, 38 mV dec-1). This work shows a new insight for HN and provides alternative opportunities in designing advanced electrocatalysts with low cost for HER in the hydrogen economy.

Regioselective Construction of Chemically Transformed Phosphide-Metal Nanoheterostructures for Enhanced Hydrogen Evolution Catalysis.

Engineering nanoheterostructures (NHs) plays a key role in exploring novel or enhanced physicochemical properties of nanocrystals. Despite previously reported synthetic methodologies, selective synthesis of NHs to achieve the anticipated composition and interface is still challenging. Herein, we presented a colloidal strategy for the regioselective construction of typical Ag-Co2P NHs with precisely controlled location of Ag nanoparticles (NPs) on unique chemically transformed Co2P nanorods (NRs) by simply changing the ratio of different surfactants. As a proof-of-concept study, the constructed heterointerface-dependent hydrogen evolution reaction (HER) catalysis was demonstrated. The multiple Ag NP-tipped Co2P NRs exhibited the best HER performance, due to their more exposed active sites and the synergistic effect at the interfaces. Our results open up new avenues in rational design and fabrication of NHs with delicate control over the spatial distribution and interfaces between different components.

Improving generation of H2O2 and •OH at copper hexacyanocobaltate/graphene/ITO composite electrode for degradation of levofloxacin in photo-electro-Fenton process.

In this work, copper hexacyanocobaltate was electro-deposited at amino-graphene-coated indium-tin-oxide glass to form multifunctional heterogeneous catalyst (CuCoG/ITO), which was confirmed by field emission scanning microscope, infrared spectra, X-ray diffraction, and electro-chemistry techniques. A novel heterogeneous photo-electro-Fenton-like system was established using CuCoG/ITO as an air-diffusion electrode, in which hydrogen peroxide (H2O2) and hydroxyl radical (•OH) could be simultaneously generated by air O2 reduction. The productive rate of •OH could reached to 70.5 µmol h-1 at - 0.8 V with 300 W visible light irradiation at pH 7.0, 0.1 M PBS. Levofloxacin could be quickly degraded at CuCoG/ITO during heterogeneous photo-electro-Fenton process in neutral media with a first-order kinetic constant of 0.49 h-1.

Preparation of molecular imprinted film based on chitosan/nafion/nano-silver/poly quercetin for clenbuterol sensing.

A useful molecular imprinted film (MIP-CNSQ/WGE) based on chitosan/nafion/nano-silver/poly quercetin compound was prepared by a compound electrochemical method at paraffin-impregnated graphite electrode for clenbuterol (CLB) sensing, which was characterised by means of field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy spectra (XPS), infrared spectra (IR) and electrochemical techniques to confirm the formation. The molecular imprinted film modified electrode was successfully applied to the determination of CLB with a reliable result. In optimum conditions, CLB at concentrations of 0.3-50.0µM could be determined with a detection limit of 0.01µM (3σ). Determination of CLB in practical samples of pork liver showed good recovery.

Ultrasonic synthesis of nickel nanostructures on glassy carbon microspheres and their application for ethanol electrooxidation.

Nickel nanostructures were synthesized onto the surface of glassy carbon microspheres (10-20 microm) with the aid of ultrasounds to produce bulk quantities of nickel micro and nanostructure surface-modified carbon microspheres (Ni-CMs). This new composite material was characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The synthesized Ni micro and nanostructures on the glassy carbon microspheres were found to possess a large proportion of Ni (111) planes. The material was proved to be of interest for electrochemical ethanol sensing in particular. An optimized limit of detection of 1.3 ppm was obtained for ethanol in aqueous solution.

The electrochemical modification of clenbuterol for biosensors of dopamine, norepinephrine, adrenalin, ascorbic acid and uric acid at paraffin-impregnated graphite electrode.

The electrochemical modification of clenbuterol (CLB) was studied at paraffin-impregnated graphite electrode (WGE) in two potential ranges of 0.0-1.6V and -1.2 to 1.2V. Various methods including X-ray photoelectron spectroscopy (XPS), UV-spectroelectrochemistry, infrared (IR) spectra and electrochemical techniques have been used to characterizing the modification. Clenbuterol can be modified at the electrode surface by carbon-nitrogen linkage or carbon-carbon linkage in 0.0-1.6V or -1.2 to 1.2V, respectively. The electrochemical behaviors of dopamine (DA), norepinephrine (NE), adrenalin (EP), ascorbic acid (AA) and uric acid (UA) were studied at clenbuterol-modified paraffin-impregnated graphite electrode (CLB/WGE), and it was found that all these compounds could be detected successfully.

A quercetin-modified biosensor for amperometric determination of uric acid in the presence of ascorbic acid.

The present work reports a quercetin-modified wax-impregnated graphite electrode (Qu/WGE) prepared through an electrochemical oxidation procedure in quercetin-containing phosphate buffer solution (PBS), for the purpose of detecting uric acid (UA) in the presence of ascorbic acid (AA). During modification quercetin was oxidized to the corresponding quinonic structure, and in the blank buffer solution the electrodeposited film exhibits a voltammetric response anticipated for the surface-immobilized quercetin. Retarding effect of the film towards the reaction of anionic species was found; therefore the pH of sample solutions was selected to ensure the analyte in molecular form. At suitable pHs the Qu/WGE shows excellent electrocatalytic effect towards the oxidation of both AA and UA, and separates the voltammetric signal of UA from AA by about 280 mV, allowing simultaneous detection of these two species. A linear relation between the peak current and concentration was obtained for UA in the range of 1-50 microM in the presence of 0.5 mM AA, with a detection limit 1.0 microM (S/N=3). This sensor was stable, reproducible and outstanding for long-term use.