Revealing the Crystal Phase-Activity Relationship on NiRu Alloy Nanoparticles Encapsulated in N-Doped Carbon towards Efficient Hydrogen Evolution Reaction.

Adjusting the crystal phase of a metal alloy is an important method to optimize catalytic performance. However, detailed understanding about the phase-property relationship for the hydrogen evolution reaction (HER) is still limited. In this work, the crystal phase-activity relationship of NiRu nanoparticles is studied employing N-doped carbon shell coated NiRu nanoparticles with different phase contents. It is found that the NiRu@NC (mix) with both face-centred cubic (fcc) and thermodynamically unstable hexagonal close-packed (hcp) phase NiRu give the best HER performance. Further activity studies demonstrate that hcp NiRu has better HER performance, and NiRu@NC (mix) with rich (∼70 %) hcp phase presented outstanding performance with an overpotential of only 27 mV @ 10 mA ⋅ cm-2 . The high HER activity of NiRu@NC (mix) is attributed to the formation of hcp phase. This finding indicates that the regulation of crystal structure can provide a new strategy for optimizing HER activity.

Facile fabrication of graphene encapsulating 3d transition metal nanoparticles as highly active and anti-poisoning catalysts for selective hydrogenation of nitroaromatics.

Graphene encapsulating 3d transition metal nanoparticles (Ni, Co, Fe@G) are successfully fabricated through pyrolysis of complexes which are simply prepared via "acid-base reactions" between metal hydroxides and carboxylic acid such as citric acid. In particular, the Ni@G catalyst exhibits outstanding catalytic activity and selectivity (>99%) toward the reduction of various nitroaromatics under mild conditions (1 MPa H2, 60 °C), even in the presence of poisons (CO and thiophene etc.). This "acid-base reactions" based method provides a facile and scalable approach to prepare graphene encapsulating 3d transition metals with wide ranges of applications.

Dual-functional Pt-on-Pd supported on reduced graphene oxide hybrids: peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic.

In this study, a facile hydrothermal method was developed to synthesize Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids. Because of the synergistic effect between Pt-on-Pd and RGO, the obtained Pt-on-Pd/RGO had superior peroxidase-mimic activities in H2O2 reduction and TMB oxidation. The reaction medium was optimized and a sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 µM of H2O2. In addition, the characteristic of electrocatalytic oxidation of methanol was investigated. The peak current density value, j(f), for the Pt-on-Pd/RGO hybrid (328 mA mg(Pt)(-1)) was about 1.85 fold higher than that of commercial Pt black (177 mA mg(Pt)(-1)) and, also, more durable electrocatalytic activity could be obtained. For the first time, the dual-functional Pt-on-Pd/RGO with peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic was reported.

Non-enzymatic electrochemical glucose sensor based on platinum nanoflowers supported on graphene oxide.

A non-enzymatic electrochemical method was developed for glucose detection using a glassy carbon electrode modified with platinum nanoflowers supported on graphene oxide (PtNFs-GO). PtNFs-GO was synthesized using a nontoxic, rapid, one-pot and template-free method. Low-cost, green solvent ethanol acted as the reductant, and the advanced and effective 2D carbon material-GO nanosheet acted as the stabilizing material. Their morphologies were characterized using transmission electron microscopy. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards glucose in neutral media. The modified electrode exhibited strong and sensitive amperometric responses to glucose even in the presence of a high concentration of chloride ions. The response time was within 5s. The interference effects from ascorbic acid and uric acid were comparatively small when operated at suitable potential. Under optimal detection potential (0.47 V with a saturated calomel reference electrode) the PtNFs-GO modified electrode performed a current response towards glucose at a broad concentration range from 2 µM to 20.3mM. Two linear regions could be observed at 2 µM to 10.3mM with a sensitivity of 1.26 µA mM(-1)cm(-2) (correlation coefficient 0.9968), and at 10.3mM to 20.3mM with a sensitivity of 0.64 µA mM(-1)cm(-2)(correlation coefficient 0.9969). The LOD of 2 µM was lower than many non-enzymatic electrochemical glucose sensors. The modified electrode was also applied to the determination of glucose in glucose injection solutions, and the satisfactory results obtained indicated that it was promising for the development of a novel non-enzymatic electrochemical glucose sensor.

An electrochemical ascorbic acid sensor based on palladium nanoparticles supported on graphene oxide.

In this study, an electrochemical ascorbic acid (AA) sensor was constructed based on a glassy carbon electrode modified with palladium nanoparticles supported on graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6 nm were homogeneously deposited on GO sheets by the redox reaction between PdCl(4)(2-) and GO. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards the oxidation of AA in neutral media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA (0.006 V) at PdNPs-GO modified electrode was shifted negatively, and the large anodic peak potential separation (0.172 V) of AA and dopamine (DA), which could contribute to the synergistic effect of GO and PdNPs, was investigated. A further amperometric experiment proved that the proposed sensor was capable of sensitive and selective sensing of AA even in the presence of DA and uric acid. The modified electrode exhibited a rapid response to AA within 5s and the amperometric signal showed a good linear correlation to AA concentration in a broad range from 20 µM to 2.28 mM with a correlation coefficient of R=0.9991. Moreover, the proposed sensor was applied to the determination of AA in vitamin C tablet samples. The satisfactory results obtained indicated that the proposed sensor was promising for the development of novel electrochemical sensing for AA determination.

Graphene and graphene-based nanomaterials: the promising materials for bright future of electroanalytical chemistry.

Similar to its popular older cousins of fullerene and carbon nanotubes (CNTs), the latest form of nanocarbon, graphene, is inspiring intensive research efforts in its own right. As an atomically thin layer of sp(2)-hybridized carbon, graphene possesses spectacular electronic, optical, magnetic, thermal and mechanical properties, which make it an exciting material in a variety of important applications. In this review, we present the current advances in the field of graphene electroanalytical chemistry, including the modern methods of graphene production, and graphene functionalization. Electrochemical (bio) sensing developments using graphene and graphene-based materials are summarized in more detail, and we also speculate on their future and discuss potential progress for their applications in electroanalytical chemistry.

Encoding electrochemiluminescence using Ru(bpy)3(2+) and fluorescein isothiocyanate co-doped silica nanoparticles.

In this paper, an electrochemiluminescence (ECL) encoding method was developed for the first time, based on a dual-dye system including Ru(bpy)(3)(2+) as an ECL emitter and fluorescein isothiocyanate (FITC) as a coding dye.

Synthesis of "clean" and well-dispersive Pd nanoparticles with excellent electrocatalytic property on graphene oxide.

Ultrafine Pd nanoparticles monodispersed on graphene oxide (GO) surfaces were successfully prepared by the redox reaction between PdCl(4)(2-) and GO. The as-made catalyst is very "clean" as a result of the surfactant-free formation process, allowing it to express high electrocatalytic ability in formic acid and ethanol oxidation relative to a commercial Pd/C catalyst. This simple and straightforward method is of significance for the facile preparation metal nanocatalysts with high catalytic activity on proper supporting materials.

A novel electrochemiluminescence sensor based on bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) covalently combined with graphite oxide.

This communication reports a novel electrochemiluminescence (ECL) sensor based on covalently linking bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (Ru(II)-NH2) with graphite oxide (GO) on a glassy carbon electrode. 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride and N-hydroxy-succinimide were applied to activate the carboxyl groups on the GO surface and catalyze the formation of amido link between Ru(II)-NH2 and carboxyl groups on GO. The composite film was characterized using atomic force microscopy, transmission electron microscopy and Fourier transform infrared absorption spectroscopy. Based on ECL experimental results, the composite film modified electrode displayed high electrochemical activity towards the oxidation of 2-(dibutylamino) ethanol (DBAE). Under optimized conditions, the linear response of ECL intensity to DBAE concentration was valid in the range 6.0×10(-7)-2.0×10(-4) mol L(-1) (r2=0.9948) with a detection limit (S/N=3) of 5.0×10(-8) mol L(-1). Furthermore, the ECL sensor presented good characteristics in terms of stability and reproducibility, promising the development of ECL sensors for biologically important compounds.