Motion‐Based,High‐Yielding,and Fast Separation of Different Charged Organics in Water

We report a self‐propelled Janus silica micromotor as a motion‐based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self‐propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s^?1. Biotin‐functionalized Janus micromotors can specifically capture and rapidly transport streptavidin‐modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self‐propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab‐on‐chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications.     

Rolled‐Up Monolayer Graphene Tubular Micromotors: Enhanced Performance and Antibacterial Property

The motion of catalytic tubular micromotors are driven by the oxygen bubbles generated from chemical reaction and is influenced by the resistance from the liquid environment. Herein, we fabricated a rolled‐up graphene tubular micromotor, in which the graphene layer was adopted as the outmost surface. Due to the hydrophobic property of the graphene layer, the fabricated micromotor performed a motion pattern that could escape from the attraction from the bubbles. In addition, Escherichia coli and Staphylococcus culture experiments proved that the graphene outer surface displays antibacterial property. Considering the bubble‐avoiding and antibacterial properties, the rolled‐up graphene tubular micromotor holds great potential for various applications such as in vivo drug delivery and biosensors.     

Nanosized IrOx–Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost‐Effective Procedure

We have developed a highly active nanostructured iridium catalyst for anodes of proton exchange membrane (PEM) electrolysis. Clusters of nanosized crystallites are obtained by reducing surfactant‐stabilized IrCl₃ in water‐free conditions. The catalyst shows a five‐fold higher activity towards oxygen evolution reaction (OER) than commercial Ir‐black. The improved kinetics of the catalyst are reflected in the high performance of the PEM electrolyzer (1 mg_Ir cm^?2), showing an unparalleled low overpotential and negligible degradation. Our results demonstrate that this enhancement cannot be only attributed to increased surface area, but rather to the ligand effect and low coordinate sites resulting in a high turnover frequency (TOF). The catalyst developed herein sets a benchmark and a strategy for the development of ultra‐low loading catalyst layers for PEM electrolysis.     

One‐step synthesis of Pt@three‐dimensional graphene composite hydrogel: an efficient recyclable catalyst for reduction of 4‐nitrophenol

A Pt@three‐dimensional graphene (Pt@3DG) composite hydrogel with a unique porous nanostructure was prepared and used as an efficient, recyclable and robust catalyst for the reduction of 4‐nitrophenol to 4‐aminophenol under mild conditions. The influence of graphene architecture on catalytic activities was comparatively investigated by loading the same amount of Pt on reduced graphene oxide. Pt@3DG exhibits a very high catalytic activity owing to the three‐dimensional macroporous framework with high specific surface area, numerous activation sites and efficient transport pathways. Moreover, catalyst separation can be easily achieved by simple filtration, and the catalyst can be reused for at least five runs, maintaining its high catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

An Efficient RuTe2/Graphene Catalyst for Electrochemical Hydrogen Evolution Reaction in Acid Electrolyte

Developing efficient powder catalysts for hydrogen evolution reaction (HER) in the acidic electrolyte is significant for hydrogen generation in the proton exchange membrane (PEM) water electrolysis technique. Herein, we demonstrated an efficient catalyst for HER in the acid media based on the graphene supported ruthenium telluride nanoparticles (RuTe₂/Gr). The catalysts were easily fabricated by a facile microwave irradiation/thermal annealing approach, and orthorhombic RuTe₂ crystals were found anchored over the graphene surface. The defective structure was demonstrated in the aberration‐corrected transmission electron microscopy images for RuTe₂ crystals and graphene support. This catalyst required an overpotential of 72 mV to drive 10 mA cm^?2 for HER when loading on the inert glass carbon electrode; Excellent catalytic stability in acidic media was also observed to offer 10 mA cm^?2 for 10 hours. The Volmer‐Tafel mechanism was indicated on RuTe₂/Gr catalyst by Tafel slope of 33 mV dec^?1, similar to that of Pt/C catalysts. The high catalytic performance of RuTe₂/Gr could be attributed to its high dispersion on the graphene surface, high electrical conductivity and low charge transfer resistance. This powder catalyst has potential application in the PEM water electrolysis technique because of its low cost and high stability.     

Micromotor‐Based Energy Generation

A micromotor‐based strategy for energy generation, utilizing the conversion of liquid‐phase hydrogen to usable hydrogen gas (H₂), is described. The new motion‐based H₂‐generation concept relies on the movement of Pt‐black/Ti Janus microparticle motors in a solution of sodium borohydride (NaBH₄) fuel. This is the first report of using NaBH₄ for powering micromotors. The autonomous motion of these catalytic micromotors, as well as their bubble generation, leads to enhanced mixing and transport of NaBH₄ towards the Pt‐black catalytic surface (compared to static microparticles or films), and hence to a substantially faster rate of H₂ production. The practical utility of these micromotors is illustrated by powering a hydrogen–oxygen fuel cell car by an on‐board motion‐based hydrogen and oxygen generation. The new micromotor approach paves the way for the development of efficient on‐site energy generation for powering external devices or meeting growing demands on the energy grid.     

Iridium(I)‐Catalyzed Regioselective CH Activation and Hydrogen‐Isotope Exchange of Non‐aromatic Unsaturated Functionality

Isotopic labelling is a key technology of increasing importance for the investigation of new C?H activation and functionalization techniques, as well as in the construction of labelled molecules for use within both organic synthesis and drug discovery. Herein, we report for the first time selective iridium‐catalyzed C?H activation and hydrogen‐isotope exchange at the β‐position of unsaturated organic compounds. The use of our highly active [Ir(cod)(IMes)(PPh₃)][PF₆] (cod=1,5‐cyclooctadiene) catalyst, under mild reaction conditions, allows the regioselective β‐activation and labelling of a range of α,β‐unsaturated compounds with differing steric and electronic properties. This new process delivers high levels of isotope incorporation over short reaction times by using low levels of catalyst loading.     

CC Coupling of Ketones with Methanol Catalyzed by a N‐Heterocyclic Carbene–Phosphine Iridium Complex

An N‐heterocyclic carbene–phosphine iridium complex system was found to be a very efficient catalyst for the methylation of ketone via a hydrogen transfer reaction. Mild conditions together with low catalyst loading (1 mol %) were used for a tandem process which involves the dehydrogenation of methanol, C?C bond formation with a ketone, and hydrogenation of the new generated double bond by iridium hydride to give the alkylated product. Using this iridium catalyst system, a number of branched ketones were synthesized with good to excellent conversions and yields.     

Synthesis of Ti‐MCM‐41 directly from silatrane and titanium glycolate and its catalytic activity1

Titanium is successfully incorporated in hexagonal mesoporous silica to form Ti‐MCM41 at low temperature. Silatrane and titanium glycolate synthesized from the oxide one‐pot synthesis process are used as the precursors. Using the cationic surfactant cetyltrimethylammonium bromide as a template, the resulting meso‐structure mimics the liquid‐crystal phase. The percentage of titanium loading is varied in the range 1–35%. The temperatures used in the preparation are 60 °C and 80 °C. After heat treatment, very high surface area mesoporous silica was obtained and characterized using diffuse reflectance UV (DRUV) spectroscopy, X‐ray diffraction (XRD), BET surface area, X‐ray fluorescence, energy dispersive spectroscopy and transmission electron microscopy (TEM). At 35% titanium, the titanium atom is also in the framework showing the pattern of hexagonal mesostructure, as shown by DRUV, XRD and TEM results. The surface area is extraordinarily high, up to more than 2300 m² g^?1, and the pore volume is as high as 1.3 cm³ g^?1 for a titanium loading range of 1–5%. Oxidative bromination reaction using Ti‐MCM‐41 as catalyst showed impressive results, with the 60 °C catalysts having higher activity. Copyright © 2005 John Wiley & Sons, Ltd.     

Defect‐Rich Co−CoOx‐Graphene Nanocatalysts for Efficient Hydrogen Production from Ammonia Borane

Chemical hydrogen storage ammonia borane has attracted extensive attention as a method of efficient utilization of hydrogen energy. The high‐efficiency catalysts are the main factor restricting the hydrogen production of ammonia borane. In this paper, the synergistic effect of Co and CoO_x supported on graphene (named Co?CoO_x@GO‐II) promotes the efficient hydrogen production of ammonia borane, and its catalytic hydrogen production rate can reach 5813 mL min^?1 g_Co^?1 at 298 K, the corresponding TOF is 15.33 min^?1. After five stability tests, Co?CoO_x @GO‐II maintained 65% of its original catalytic performance. The synergy of metal and metal oxide and the defects in the atomic arrangement ensure the catalytic activity, the large specific surface area of graphene ensures the dispersion and fixation. This strategy may provide a possibility to design high‐performance transition metal catalysts.     

Hyperporous‐Carbon‐Supported Nonprecious Metal Electrocatalysts for the Oxygen Reduction Reaction

Highly porous carbonaceous nonprecious metal catalysts for the oxygen reduction reaction are prepared by carbonization of low‐cost metalloporphyrin‐based hyper‐crosslinked polymers (MPH‐X). With high surface area (2768 m² g⁻¹), hierarchical porous structure, and high metal loading (9.97 wt %), the obtained hyperporous carbon MPH‐Fe/C catalyst exhibits high oxygen reduction reaction (ORR) activity with a half‐wave potential (0.816 V) that is comparable to the 0.819 V of commercial Pt/C. Stability tests reveal that MPH‐Fe/C also exhibits outstanding long‐term durability and methanol tolerance. Our findings may offer an alternative approach to produce nonprecious metal ORR catalysts on a large scale owing to the low‐cost MPH‐X precursors with diverse metal types.     

Label‐free Electrochemical Aptasensor for Carcino‐embryonic Antigen Based on Ternary Nanocomposite of Gold Nanoparticles,Hemin and Graphene

In this report, a label‐free electrochemical aptasensor for carcino‐embryonic antigen (CEA) was successfully developed based on a ternary nanocomposite of gold nanoparticles, hemin and graphene nanosheets (AuNPs‐HGNs). This nanocomposite was prepared by decorating gold nanoparticles on the surface of hemin functionalized graphene nanosheets via a simple wet‐chemical strategy. The aptamer can be assembled on the surface of AuNPs‐HGNs/GCE (glassy carbon electrode) through Au‐S covalent bond to form the sensing interface. Hemin absorbed on the graphene nanosheets not only acts as a protective agent of graphene sheets, but also as an in situ probe base on its excellent redox properties. Gold nanoparticles provide with both numerous binding sites for loading CEA binding aptamer (CBA) and good conductivity to promote the electron transfer. The current changes, which are caused by CEA specifically binding on the modified electrode, are exploited for the label‐free detection of CEA in a very rapid and convenient protocol. Therefore, the method has advantages of high sensitivity, wide linear range (0.0001–10 ng mL^?1), low detection limit (40 fg mL^?1) and attractive specificity. The results illustrate that the proposed label‐free electrochemical aptasensor has a potential application in the biological or clinical target analysis for its simple operation and low cost.     

Carbon‐Supported Copper Nanomaterials: Recyclable Catalysts for Huisgen [3+2] Cycloaddition Reactions

Highly disperse copper nanoparticles immobilized on carbon nanomaterials (CNMs; graphene/carbon nanotubes) were prepared and used as a recyclable and reusable catalyst to achieve Cu^I‐catalyzed [3+2] cycloaddition click chemistry. Carbon nanomaterials with immobilized N‐heterocyclic carbene (NHC)‐Cu complexes prepared from an imidazolium‐based carbene and Cu^I show excellent stability including high efficiency at low catalyst loading. The catalytic performance evaluated in solution and in bulk shows that both types of Cu‐CNMs can function as an effective recyclable catalysts (more than 10 cycles) for click reactions without decomposition and the use of external additives.     

Achieving Simultaneous CO2 and H2S Conversion via a Coupled Solar‐Driven Electrochemical Approach on Non‐Precious‐Metal Catalysts

Carbon dioxide (CO₂) and hydrogen sulfide (H₂S) are generally concomitant with methane (CH₄) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO₂ and H₂S into value‐added products is attractive; however it has not received enough attention. A solar‐driven electrochemical process is demonstrated using graphene‐encapsulated zinc oxide catalyst for CO₂ reduction and graphene catalyst for H₂S oxidation mediated by EDTA‐Fe²⁺/EDTA‐Fe³⁺ redox couples. The as‐prepared solar‐driven electrochemical system can realize the simultaneous conversion of CO₂ and H₂S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits.     

Ultrafine Molybdenum Carbide Nanoparticles Composited with Carbon as a Highly Active Hydrogen‐Evolution Electrocatalyst

The replacement of platinum with non‐precious‐metal electrocatalysts with high efficiency and superior stability for the hydrogen‐evolution reaction (HER) remains a great challenge. Herein, we report the one‐step synthesis of uniform, ultrafine molybdenum carbide (Mo₂C) nanoparticles (NPs) within a carbon matrix from inexpensive starting materials (dicyanamide and ammonium molybdate). The optimized catalyst consisting of Mo₂C NPs with sizes lower than 3 nm encapsulated by ultrathin graphene shells (ca. 1–3 layers) showed superior HER activity in acidic media, with a very low onset potential of ?6 mV, a small Tafel slope of 41 mV dec^?1, and a large exchange current density of 0.179 mA cm^?2, as well as good stability during operation for 12 h. These excellent properties are similar to those of state‐of‐the‐art 20 % Pt/C and make the catalyst one of the most active acid‐stable electrocatalysts ever reported for HER.     

Sensitivity Enhancement in Nickel Hydroxide/3D‐Graphene as Enzymeless Glucose Detection

A nickel hydroxide (Ni(OH)₂)/3D‐graphene composite is used as monolithic free‐standing electrode for enzymeless electrochemical detection of glucose. Ni(OH)₂ nanoflakes are synthesized by using a simple solution growth procedure on 3D‐graphene foam which was grown by chemical vapor deposition (CVD). The pore structure of 3D‐graphene allows easy access to glucose with high surface area, which leads to glucose detection with an ultrahigh sensitivity of 3.49 mA mM^?1 cm^?2 and a significant lower detection limit up to 24 nM. Cyclic voltammetry (CV) and potentionstatic mode is used for non‐enzymatic glucose sensing. The impedance and effective surface area have been studied well. The high sensitivity, low detection limit and simple configuration of Ni(OH)₂/three dimensional (3D)‐graphene composite electrodes can evoke its industrial application in glucose sensing devices.     

Hydrogen Bond Directed ortho‐Selective C−H Borylation of Secondary Aromatic Amides

Reported is an iridium catalyst for ortho‐selective C?H borylation of challenging secondary aromatic amide substrates, and the regioselectivity is controlled by hydrogen‐bond interactions. The BAIPy ‐Ir catalyst forms three hydrogen bonds with the substrate during the crucial activation step, and allows ortho‐C?H borylation with high selectivity. The catalyst displays unprecedented ortho selectivities for a wide variety of substrates that differ in electronic and steric properties, and the catalyst tolerates various functional groups. The regioselective C?H borylation catalyst is readily accessible and converts substrates on gram scale with high selectivity and conversion.     

Graphitic Carbon Nitride Nanoribbons: Graphene‐Assisted Formation and Synergic Function for Highly Efficient Hydrogen Evolution

The development of new promising metal‐free catalysts is of great significance for the electrocatalytic hydrogen evolution reaction (HER). Herein, a rationally assembled three‐dimensional (3D) architecture of 1D graphitic carbon nitride (g‐C₃N₄) nanoribbons with 2D graphene sheets has been developed by a one‐step hydrothermal method. Because of the multipathway of charge and mass transport, the hierarchically structured g‐C₃N₄ nanoribbon–graphene hybrids lead to a high electrocatalytic ability for HER with a Tafel slope of 54 mV decade^?1, a low onset overpotential of 80 mV and overpotential of 207 mV to approach a current of 10 mA cm^?2, superior to those non‐metal materials and well‐developed metallic catalysts reported previously. This work presents a great advance for designing and developing highly efficient metal‐free catalyst for hydrogen evolution.     

Facile Fabrication of Graphene‐Containing Foam as a High‐Performance Anode for Microbial Fuel Cells

Facile fabrication of novel three‐dimensional anode materials to increase the bacterial loading capacity and improve substrate transport in microbial fuel cells (MFCs) is of great interest and importance. Herein, a novel graphene‐containing foam (GCF) was fabricated easily by freeze‐drying and pyrolysis of a graphene oxide–agarose gel. Owing to the involvement of graphene and stainless‐steel mesh in the GCF, the GCF shows high electrical conductivity, enabling the GCF to be a conductive electrode for MFC applications. With the aid of agarose, the GCF electrode possesses a supermacroporous structure with pore sizes ranging from 100–200 μm and a high surface area, which greatly increase the bacterial loading capacity. Cell viability measurements indicate that the GCF possesses excellent biocompatibility. The MFC, equipped with a 0.4 mm‐thick GCF anode, shows a maximum area power density of 786 mW m^?2, which is 4.1 times that of a MFC equipped with a commercial carbon cloth anode. The simple fabrication route in combination with the outstanding electrochemical performance of the GCF indicates a promising anode for MFC applications.     

Graphene‐Based Composite with γ‐Fe2O3 Nanoparticle for the High‐Performance Removal of Endocrine‐Disrupting Compounds from Water

Graphene is a 2D sp²‐hybridized carbon sheet and an ideal material for the adsorption‐based separation of organic pollutants. However, such potential applications of graphene are largely limited, owing to their poor solubility and extensive aggregation properties through graphene? graphene interactions. Herein, we report the synthesis of graphene‐based composites with γ‐Fe₂O₃ nanoparticle for the high‐performance removal of endocrine‐disrupting compounds (EDC) from water. The γ‐Fe₂O₃ nanoparticles partially inhibit these graphene? graphene interactions and offer water dispersibility of the composite without compromising much of the high surface area of graphene. In their dispersed form, the graphene component offers the efficient adsorption of EDC, whilst the magnetic iron‐oxide component offers easier magnetic separation of adsorbed EDC.