It is commonly accepted that it is almost not possible to realize the large-scale practical application of fuel cells if the expensive noble metal-based electrocatalysts for oxygen reduction reactions (ORR) cannot be replaced by other low-cost, efficient, and stable ones. Herein, our studies demonstrate that iron phthalocyanine (FePc) supported on chemically reduced graphene through π–π interaction can act as a noble metal-free electrocatalyst with a comparable activity, long-term operation stability, and better tolerance to methanol crossover and CO poisoning compared with commercial Pt/C for ORR in alkaline media. The improved electrochemical activity and stability of FePc by graphene is mainly attributed to the inherent properties of graphene and the π-stacking interaction between FePc and planar aromatic structure of graphene. The as-prepared graphene–iron phthalocyanine (g-FePc) composite exhibits an efficient 4-electron pathway and can be used as a promising Pt-free ORR electrocatalyst.Keywords: fuel cells; graphene; iron phthalocyanine; noble metal-free electrocatalyst; oxygen reduction reaction

Graphene-supported PtPd alloy nanocubes (PtPd/RGO) were synthesized via a facile and versatile one-pot hydrothermal synthetic strategy, which proved to be a universal technique for preparing other graphene-supported alloy nanocrystals. In acidic electrolyte, the PtPd/RGO composites exhibited much enhanced electrocatalytic activity toward methanol oxidation compared to the unsupported PtPd alloy nanocubes with a similar size and shape, and the commercial Pt/C catalyst. More interestingly, we found that CO stripping is an efficient method to remove the surfactants wrapped on the particle surface and thus enhance the electrocatalytic performance of the Pt-based nanocrystals. After CO stripping treatment, the PtPd/RGO composites exhibited a much more negative onset potential of methanol oxidation than those of the unsupported PtPd alloy nanocubes and the commercial Pt/C catalyst. Moreover, the treated PtPd/RGO displayed a mass-specific methanol oxidation activity of 198 mA/mg Metal at 0.62 V (vs Ag/AgCl), nearly 3.14 times higher than those of the unsupported PtPd alloy nanocubes (63 mA/mgMetal) and the commercial Pt/C catalyst (64 mA/mgMetal). On the other hand, the PtPd/RGO exhibited much higher stability during the methanol electrooxidation with almost no loss of the electrochemical active surface area (ECSA) and activity after 1000 electrochemical cycles. On the contrary, the unsupported PtPd nanocubes and the commercial Pt/C catalyst lost 8.5% and 25.7% of their initial ECSA, and 6.2% and 20.6% of the initial peak current after 1000 cycles of methanol oxidation reaction. The excellent stability of the PtPd/RGO can also be reflected from the fact that the morphology, size, and dispersity of the PtPd nanocubes exhibited no significant change after 1000 potential cycles.

► Porous and alloy-structured PtPd nanorods are successfully synthesized.► The structure of the PtPd nanorods is characterized by TEM, XRD and XPS.► The porous structure can effectively improve the surface area and reduce the noble-metal loading.► The PtPd nanorods exhibit enhanced catalytic activity and improved durability for ORR.► Such porous nanomaterials are promising cathode electrocatalysts for fuel cells.Through a bromide-induced galvanic replacement reaction between Pd nanowires and K2PtCl6, PtPd porous nanorods are successfully synthesized. With such interesting porous and alloy-structured PtPd nanorods as cathode catalyst for oxygen reduction reaction (ORR), obvious advantages are shown evidently in the electrochemical studies. First, the porous structure shows large electrochemical surface area (ECSA), thus providing an efficient way to reduce the usage of expensive noble metals. Second, due to the large surface area and the synergistic effect of alloy crystalline phase, the resulting porous nanorods exhibit enhanced catalytic activity for ORR compared to the Pd nanowires and commercial Pt/C catalyst. Third, the PtPd porous nanorods exhibit excellent durability in ORR with only 5.88% loss of the initial ECSA after the accelerated durability tests (1000 potential cycles), whereas the Pd nanowires and commercial Pt/C catalyst lose 21.6% and 40.4% of their original ECSA. Such porous nanorods appear to be promising cathode electrocatalysts for fuel cells with enlarged surface area, enhanced catalytic activity and improved durability.Graphical abstract

In this study, a sensor for the detection of glucose and hydrogen peroxide was developed on the basis of Cu2O nanocubes wrapped by graphene nanosheets (Cu2O/GNs) as electrocatalysts. Cubic Cu2O nanocrystals/graphene hybrid has been successfully fabricated by a chemical reduction method at low temperature. The morphologies of the synthesized materials were characterized by scanning electron microscopy (SEM) and powder X-ray diffraction measurements (XRD). As a non-enzymatic amperometric sensor, the resulting Cu2O/graphene composite exhibited high sensitivity for the detection of glucose and H2O2. Moreover, the graphene coating was found to be able to effectively improve the electrochemical cycling stability of the fabricated sensor. With the Cu2O/GNs modified electrode, amperometric sensing of glucose was realized with a linear response over the concentration range from 0.3 to 3.3 mM, a detection limit of 3.3 μM (S/N=3), high selectivity and short response time (<9 s). Compared to unsupported Cu2O nanocubes, the graphene-wrapped Cu2O nanocubes exhibited higher catalytic activity for glucose oxidation with higher sensitivity and lower detection limit. The enzymeless sensor also exhibited good response toward H2O2, with the linear response ranging from 0.3 to 7.8 mM at −0.4 V and the detection limit of 20.8 μM. Moreover, because the surface is covered by graphene nanosheets, the as-synthesized Cu2O/GNs exhibited improved electrochemical stability. Such novel graphene nanosheets wrapped Cu2O nanocubes represent promising enzyme-free glucose and hydrogen peroxide sensors with high sensitivity and selectivity, improved stability and fast amperometric response.Highlights► Graphene nanosheets wrapped Cu2O nanocubes (Cu2O/GNs) are successfully fabricated by the chemical reduction method at low temperature. ► As a non-enzymatic amperometric sensor, the Cu2O/GNs exhibit high sensitivity and selectivity for the detection of glucose. ► The enzymeless sensor exhibits good response toward H2O2 with the detection limit of 20.8 μM. ► Because the surface is covered by graphene nanosheets, the as-synthesized Cu2O nanocubes exhibit improved electrochemical stability.

Sensitive and selective detection of 2,4,6-trinitrotoluene (TNT) has attracted considerable attention due to the wide applications of TNT as explosive material. Many efforts have been made to develop various sensors for detecting TNT in recent years. We herein report a novel sensor based on p-aminothiophenol (PATP) functionalized silver nanoparticles supported on graphene nanosheets (Ag/GNs), which was found to be a kind of effective chemosensor for the ultratrace detection of TNT by using surface enhanced Raman scattering (SERS). In the present hybrid material, PATP is paired together to form a corresponding azo compound p, p′-dimercaptoazobenzene (DMAB) and thus can be used as a model Raman probe. The π-donor–acceptor interaction between π-acceptor TNT and π-donor DMAB-Ag/GNs complex can effectively induce the “hot spots” for SERS. The intense spectral resonance from the DMAB–TNT–DMAB bridges formed between the Ag/GNs nanosheets could result in enhanced Raman signals of DMAB molecules with the presence of ultratrace TNT. SERS measurements demonstrated that TNT with concentration as low as 10−11 M can be detected by using the present SERS platform. The present study not only provides a facile method for ultrasensitive and selective detection of TNT but also could develop a graphene-based SERS platform.Highlights► Graphene nanosheets supported silver nanoparticles (Ag/GNs) are successfully synthesized. ► p-aminothiophenol (PATP) functionalized Ag/GNs (PATP-Ag/GNs) can be used as a model Raman probe. ► PATP-Ag/GNs is a kind of effective chemosensor for the ultratrace detection of TNT by using SERS. ► This study provides a facile method for TNT detection and a novel graphene-based SERS platform.

Sub-nanometre sized metal clusters, with dimensions between metal atoms and nanoparticles, have attracted more and more attention due to their unique electronic structures and the subsequent unusual physical and chemical properties. However, the tiny size of the metal clusters brings the difficulty of their synthesis compared to the easier preparation of large nanoparticles. Up to now various synthetic techniques and routes have been successfully applied to the preparation of sub-nanometre clusters. Among the metals, gold clusters, especially the alkanethiolate monolayer protected clusters (MPCs), have been extensively investigated during the past decades. In recent years, silver and copper nanoclusters have also attracted enormous interest mainly due to their excellent photoluminescent properties. Meanwhile, more structural characteristics, particular optical, catalytic, electronic and magnetic properties and the related technical applications of the metal nanoclusters have been discovered in recent years. In this critical review, recent advances in sub-nanometre sized metal clusters (Au, Ag, Cu, etc.) including the synthetic techniques, structural characterizations, novel physical, chemical and optical properties and their potential applications are discussed in detail. We finally give a brief outlook on the future development of metal nanoclusters from the viewpoint of controlled synthesis and their potential applications.

Bimetallic alloy PdAg nanowires were synthesized by a facile one-step wet chemical strategy. The unique nanostructure with large surface area and active surface (111) planes make them promising electrocatalysts for direct-liquid fuel cells. The electrochemical studies indicated that the PdAg alloy nanowires exhibit enhanced electrocatalytic activity toward formic acid oxidation with larger oxidation current density, higher tolerance to CO poisoning, and more negative onset potential in comparison with the commercial Pd/C catalysts. At the same potentials, the as-synthesized PdAg nanowires show higher long-term stability than Pd/C catalysts in the chronoamperometric analyses. The electron transfer kinetics of HCOOH oxidation on the PdAg nanowires was studied with electrochemical impedance spectroscopy (EIS). It was found that the charge transfer resistance (RCT) of formic acid oxidation on PdAg nanowires is much smaller than that obtained from a Pd/C catalyst, which suggests that the electron-transfer kinetics for formic acid oxidation at the synthesized PdAg nanowires is highly facilitated. The present work highlights the facile synthesis of the homogeneous PdAg alloy nanowires and their potential application as anode electrocatalyst of fuel cells.Keywords: electrocatalysis; electrochemical impedance spectroscopy; formic acid oxidation; fuel cell; PdAg nanowire;

Graphene and graphene oxide (GO) attract increasing attention due to their unique physical and chemical properties and thus the potential applications in optics and electronics. However, the gapless band structure greatly limits their wide applications in opto-electronic devices. Surface functionalization was found to be an effective method to tune the properties of graphene and GO. In the present report, GO hybrid materials with blue-emission were fabricated through the GO surface functionalization with aryl diazonium salts of 2-aminoanthracene. The obtained hybrids were carefully characterized with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), Raman spectroscopy and UV-Vis absorption spectroscopy. Significantly different from the cyan emission (∼491 nm) of monomeric 2-aminoanthracene, the as-synthesized GO hybrid composites exhibited strong blue photoluminescence centered at ca. 400 nm. The large blue shift of the luminescence (∼91 nm) obtained from the functionalized GO could be partly ascribed to the rigid chemical environment with anthryl moieties chemically bonded onto GO surface. Such surface-functionalized GO hybrids with unique optical properties render them exciting materials for opto-electronic devices.

Well-dispersed Pd nanoparticles supported on carbon nanodots are synthesized successfully with a facile and green method without any additional surfactant and reductant. The synthesized Pd–C hybrid nanoparticles provide high electrical conductivity and non-blocked active surfaces for organic molecular fuels oxidation. Compared to the commercial Pd/C catalysts, the present Pd–C hybrid nanocomposites exhibit more negative onset potential and much higher current density for methanol oxidation in alkaline media. The excellent electrocatalytic performance displayed in the electrochemical measurements indicates that such “naked” Pd nanoparticles have potential applications as promising anode catalysts in alkaline fuel cells.Graphical abstractHighlights► “Naked” Pd nanoparticles supported on carbon nanodots are synthesized. ► The structure of the Pd–C hybrid nanomaterials are characterized with TEM, XRD and XPS measurements. ► The Pd–C hybrid nanocomposites exhibit high catalytic activity for methanol oxidation in alkaline media.

Two different sized silver nanoclusters are prepared by two different synthetic routs. First, a small nanocluster (NC) which is 0.7 nm in diameter was synthesized by using meso-2, 3-dimercapto-succinic acid (DMSA) as a capping ligand, and second a larger nanoparticle (NP) which is 3.3 nm in diameter was prepared by chemical reduction and coated with DMSA. The as-prepared silver nanoclusters or nanoparticles are then loaded onto a glassy carbon electrode and the size effect on their electrocatalytic activity toward oxygen reduction reaction (ORR) is investigated with electrochemical techniques in alkaline electrolyte. The cyclic voltammetric (CV) studies show that the onset potential of ORR on 0.7 nm silver nanoclusters is 150 mV more positive than that from 3.3 nm silver nanoparticles. And compared to the larger nanoparticles, five times higher current density of ORR at −0.80 V is obtained from the 0.7 nm silver nanoclusters. These CV results indicate that the smaller Ag nanoclusters exhibit higher catalytic performance for ORR. Rotating disk voltammetric studies show ORR on both DMSA monolayer-protected silver clusters is dominated first by a two-electron transfer pathway to produce H2O2 and then peroxide is reduced by 2 more electrons to produce water.Highlights► 0.7 and 3.3 nm silver nanoclusters are synthesized. ► 0.7 nm Ag nanoclusters exhibit higher catalytic activity toward ORR than that of the larger clusters. ► Two-electron transfer pathway of ORR is dominated with Ag nanoclusters as catalysts.

In the present study, we demonstrate a novel method to synthesize the graphene-supported AgPd alloy nanocrystals (AgPd/GO) which exhibit unique hollow structure and excellent electrocatalytic activity for H2O2 reduction. The hybrid nanomaterials were synthesized via a two-step method. The graphene supported Ag nanoparticles (Ag/GO) were first synthesized by using sodium citrate as both reducing and stabilizing agents. AgPd alloy nanoparticles supported on graphene (AgPd/GO) were then prepared through a galvanic displacement reaction at 100 °C. The structure of the prepared materials was characterized with UV-visible spectroscopy and transmission electron microscopy (TEM). The electrochemical measurements showed that the AgPd/GO have excellent electrocatalytic activity toward the reduction of hydrogen peroxide. Such hollow Ag/Pd alloy nanoparticles supported on graphene exhibited a low detection limit (1.4 μM) and good linear ranges (0.01–1.4 mM) for H2O2 detection, which render them the suitable electrochemical sensors for hydrogen peroxide detection in practical applications.

Metal nanoclusters with a core size smaller than 2 nm have attracted much attention because of their unique physical and chemical properties. Among the studied metal nanoclusters, gold and silver have been studied extensively by size-controlled synthesis, structural characterization and properties investigations. Recently, considerable research effort has been devoted to the investigation of copper nanoclusters. In this review, we highlight recent progress in the study of copper nanoclusters in terms of synthesis methods, characterization techniques and their novel optical and catalytic properties.

Subnanometer-sized copper nanoclusters were prepared by a one-pot procedure based on wet chemical reduction. The structural characteristics of the 2-mercapto-5-n-propylpyrimidine-protected nanoclusters, Cun (n ≤ 8), were determined by mass spectrometry. The Cu nanoclusters displayed apparent luminescence, with dual emissions at 425 and 593 nm, with quantum yields of 3.5 and 0.9%, respectively, and high electrocatalytic activity in the electoreduction of oxygen.

Copper nitride nanocubes are synthesized in a facile one-phase process. The crystal size could be tuned easily by using different primary amines as capping agents. Such Pt-free nanocrystals exhibit electrocatalytic activity toward oxygen reduction and appear to be promising cathodic electrocatalysts in alkaline fuel cells.

Nanostructured copper sulfides have attracted much attention due to their unique electronic and optical properties and potential applications in many areas. This article presents a high-temperature precursor-injection method to synthesize covellite copper sulfide (CuS) nanoplates by using oleylamine as capping ligands. The synthesized CuS nanoplates were found to be self-assembled into face-to-face one-dimensional columnar arrays with the longest column of 0.75 μm. Further studies showed that the reaction temperature has strong effects on the size, size distribution and the self-assembly behaviors of the CuS nanoplates. The self-assembly behaviors were found to be tuned by the reaction temperature. In the range of 140–180 °C, the face-to-face self-assembly is formed over the entire substrate, whereas only edge-to-edge arrangements were observed at the reaction temperature of 200 °C. As the temperature further increases, the product exhibits a mixture of large and small nanocrystals and there is not any presence of self-assembly. The present study highlights the size-controlled synthesis of copper sulfide nanoplates and their self-assembly behaviors dependent on reaction temperature.

Hydrogen storage is one of the vital and challenging issues for the commercialization of hydrogen-powered fuel cells. In this report, the synthesized PdAg nanotubes exhibit enhanced hydrogen-storage ability. The highest capacity for hydrogen absorption obtained on the PdAg nanotubes with 15% of Pd was over 200 times greater than the pure Pd nanoparticles.

IrxPt100−x alloy nanoparticles with varied compositions (x = 100, 75, 67, 50, 34, and 0) were synthesized by a thermolytic process at varied ratios of the IrCl3 and PtCl2 precursors. High-resolution transmission electron microscopic (HRTEM) measurements showed that the nanoparticles all exhibited well-defined crystalline structures with the average core diameters around 2 nm; and the elemental compositions were determined by X-ray photoelectron spectroscopic (XPS) measurements. The electrocatalytic activities of the IrxPt100−x nanoparticles toward formic acid oxidation were then examined by electrochemical measurements, including cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). In the CV studies, it was found that both the current density of formic acid oxidation and the tolerance to CO poisoning were strongly dependent on the composition of the iridium-platinum alloy nanoparticles, with the best performance found with the Ir50Pt50 nanoparticles. Due to heavy CO poisoning, Pt nanoparticles exhibited the lowest catalytic performance among the series of nanoparticles (excluding Ir nanoparticles). The Ir50Pt50 nanoparticles also showed the maximum current density and stability in chronoamperometric measurements. Consistent results were obtained in electrochemical impedance spectroscopic studies of the electron transfer kinetics involved. Notably, of all the nanoparticle electrocatalysts, an inductive component, i.e. negative impedance, was observed in the potential windows where CO was removed by electro-oxidation; and the charge transfer resistance was found to be the lowest with the Ir50Pt50 nanoparticles. Based on the current density and peak potential of formic acid oxidation, the ratio of the anodic peak current density to the cathodic peak current density measured in CV studies, the stability manifested in chronoamperometric measurements and the tolerance to CO poisoning displayed in EIS measurements, the electrocatalytic performance of the IrPt alloy nanoparticles was found to decrease in the order of Ir50Pt50 > Ir67Pt33 > Ir75Pt25 > Ir34Pt66 > Pt. That is, among the series of IrPt alloy nanoparticles, the sample with the Ir/Pt atomic ratio of 1:1 showed the highest electrocatalytic activity towards formic acid oxidation, which might be ascribed to the bifunctional reaction mechanism of bimetallic alloy electrocatalysts.

We demonstrate the synthesis of monodisperse, heterostructured Pt–Ru nanocrystals with a novel core–shell structure by a one-step method. The Pt–Ru nanocrystals show excellent electrocatalytic activity towards formic acid oxidation. Such core–shell structured Pt–Ru nanocrystals are potential candidates as anode catalysts in fuel cells.

Uniform and ultralong silver nanorods are synthesized with a wet chemical reduction method by using PVP as a stabilizer. The crystal structure and morphology of the synthesized nanorods are characterized with transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and UV–vis absorption spectroscopy. The electrocatalytic activity of the Ag nanorods with and without PVP stabilizer, towards oxygen reduction reaction (ORR), is studied and compared by cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements in alkaline solution. Compared to the low current density and incomplete two-electron reaction process of ORR with PVP-protected Ag nanorods, the catalytic activity of the Ag nanorods with removal of the PVP is found to be enhanced remarkably with much higher oxygen reduction current density and the most efficient four-electron process.

Nanoneedle-covered palladium−silver nanotubes were synthesized through a galvanic displacement reaction with Ag nanorods at 100 °C (PdAg-100) and room temperature (PdAg-25). Transmission and scanning electron microscopic measurements displayed that the synthesized PdAg nanotubes exhibit a hollow structure with a nanoneedle-covered surface, providing the perfect large surface area for catalytic reactions. The PdAg nanotubes formed at 100 °C exhibit a more uniform surface morphology than those obtained at room temperature. The high-resolution TEM, energy-dispersive X-ray analysis, and powder X-ray diffraction measurements indicated that the surface of the nanotubes is decorated with crystalline Pd nanoparticles with Pd(111) planes, and meanwhile, Ag and AgCl particles are dispersed in the inner space of the nanotubes. The electrocatalytic activity of the synthesized PdAg nanotubes toward formic acid oxidation was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). With the same loading on a glassy carbon electrode, the PdAg-100 nanotubes show high catalytic activity and stability from the CV and chronoamperometric analyses, which may be ascribed to the annealing process of the nanotube surface structures at 100 °C. The reaction kinetics of the HCOOH oxidation on the PdAg nanotubes was then examined by EIS measurements. It was found that the impedance responses are strongly dependent on the electrode potentials. With the potential increasing, the reaction kinetics evolve from resistive to pseudoinductive and then to inductive behaviors. On the basis of the proposed equivalent circuits, the synthesized PdAg nanotubes exhibit a much lower (almost 3 orders of magnitude smaller) charge-transfer resistance (RCT, a characteristic quantity for the rate of charge transfer for the electrooxidation of formic acid) than that obtained at the Pt-based nanoparticles reported previously. It was also found that the RCT at the PdAg-100 nanorods is much smaller than that at the PdAg-25 nanorods, indicating the electron-transfer kinetics for formic acid oxidation at the PdAg-100 nanorods is much better facilitated. The present work highlights the application of the nanoneedle-covered PdAg nanotubes with high surface areas as anode electrocatalysts in fuel cells and the influence of surface structure on their catalytic activity.

Sub-nanometre sized metal clusters, with dimensions between metal atoms and nanoparticles, have attracted more and more attention due to their unique electronic structures and the subsequent unusual physical and chemical properties. However, the tiny size of the metal clusters brings the difficulty of their synthesis compared to the easier preparation of large nanoparticles. Up to now various synthetic techniques and routes have been successfully applied to the preparation of sub-nanometre clusters. Among the metals, gold clusters, especially the alkanethiolate monolayer protected clusters (MPCs), have been extensively investigated during the past decades. In recent years, silver and copper nanoclusters have also attracted enormous interest mainly due to their excellent photoluminescent properties. Meanwhile, more structural characteristics, particular optical, catalytic, electronic and magnetic properties and the related technical applications of the metal nanoclusters have been discovered in recent years. In this critical review, recent advances in sub-nanometre sized metal clusters (Au, Ag, Cu, etc.) including the synthetic techniques, structural characterizations, novel physical, chemical and optical properties and their potential applications are discussed in detail. We finally give a brief outlook on the future development of metal nanoclusters from the viewpoint of controlled synthesis and their potential applications.

IrxPt100−x alloy nanoparticles with varied compositions (x = 100, 75, 67, 50, 34, and 0) were synthesized by a thermolytic process at varied ratios of the IrCl3 and PtCl2 precursors. High-resolution transmission electron microscopic (HRTEM) measurements showed that the nanoparticles all exhibited well-defined crystalline structures with the average core diameters around 2 nm; and the elemental compositions were determined by X-ray photoelectron spectroscopic (XPS) measurements. The electrocatalytic activities of the IrxPt100−x nanoparticles toward formic acid oxidation were then examined by electrochemical measurements, including cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). In the CV studies, it was found that both the current density of formic acid oxidation and the tolerance to CO poisoning were strongly dependent on the composition of the iridium-platinum alloy nanoparticles, with the best performance found with the Ir50Pt50 nanoparticles. Due to heavy CO poisoning, Pt nanoparticles exhibited the lowest catalytic performance among the series of nanoparticles (excluding Ir nanoparticles). The Ir50Pt50 nanoparticles also showed the maximum current density and stability in chronoamperometric measurements. Consistent results were obtained in electrochemical impedance spectroscopic studies of the electron transfer kinetics involved. Notably, of all the nanoparticle electrocatalysts, an inductive component, i.e. negative impedance, was observed in the potential windows where CO was removed by electro-oxidation; and the charge transfer resistance was found to be the lowest with the Ir50Pt50 nanoparticles. Based on the current density and peak potential of formic acid oxidation, the ratio of the anodic peak current density to the cathodic peak current density measured in CV studies, the stability manifested in chronoamperometric measurements and the tolerance to CO poisoning displayed in EIS measurements, the electrocatalytic performance of the IrPt alloy nanoparticles was found to decrease in the order of Ir50Pt50 > Ir67Pt33 > Ir75Pt25 > Ir34Pt66 > Pt. That is, among the series of IrPt alloy nanoparticles, the sample with the Ir/Pt atomic ratio of 1:1 showed the highest electrocatalytic activity towards formic acid oxidation, which might be ascribed to the bifunctional reaction mechanism of bimetallic alloy electrocatalysts.

Graphene and graphene oxide (GO) attract increasing attention due to their unique physical and chemical properties and thus the potential applications in optics and electronics. However, the gapless band structure greatly limits their wide applications in opto-electronic devices. Surface functionalization was found to be an effective method to tune the properties of graphene and GO. In the present report, GO hybrid materials with blue-emission were fabricated through the GO surface functionalization with aryl diazonium salts of 2-aminoanthracene. The obtained hybrids were carefully characterized with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), Raman spectroscopy and UV-Vis absorption spectroscopy. Significantly different from the cyan emission (∼491 nm) of monomeric 2-aminoanthracene, the as-synthesized GO hybrid composites exhibited strong blue photoluminescence centered at ca. 400 nm. The large blue shift of the luminescence (∼91 nm) obtained from the functionalized GO could be partly ascribed to the rigid chemical environment with anthryl moieties chemically bonded onto GO surface. Such surface-functionalized GO hybrids with unique optical properties render them exciting materials for opto-electronic devices.

We demonstrate the synthesis of monodisperse, heterostructured Pt–Ru nanocrystals with a novel core–shell structure by a one-step method. The Pt–Ru nanocrystals show excellent electrocatalytic activity towards formic acid oxidation. Such core–shell structured Pt–Ru nanocrystals are potential candidates as anode catalysts in fuel cells.