A strategy to overcome the unsatisfying catalytic performance and the durability of monometallic iron‐based materials for the electrochemical oxygen evolution reaction (OER) is provided by heterobimetallic iron–metal systems. Monometallic Fe catalysts show limited performance mostly due to poor conductivity and stability. Here, by taking advantage of the structurally ordered and highly conducting FeSn2 nanostructure, for the first time, an intermetallic iron material is employed as an efficient anode for the alkaline OER, overall water‐splitting, and also for selective oxygenation of organic substrates. The electrophoretically deposited FeSn2 on nickel foam (NF) and fluorine‐doped tin oxide (FTO) electrodes displays remarkable OER activity and durability with substantially low overpotentials of 197 and 273 mV at 10 mA cm−2, respectively, which outperform most of the benchmarking NiFe‐based catalysts. The resulting superior activity is attributed to the in situ generation of α‐FeO(OH)@FeSn2 where α‐FeO(OH) acts as the active site while FeSn2 remains the conductive core. When the FeSn2 anode is coupled with a Pt cathode for overall alkaline water‐splitting, a reduced cell potential (1.53 V) is attained outperforming that of noble metal‐based catalysts. FeSn2 is further applied as an anode to produce value‐added products through selective oxygenation reactions of organic substrates.
The synthesis of structurally ordered non-noble intermetallic cobalt stannide (CoSn 2 )n anocrystals and their utilization for high-performance electrocatalytic overall watersplitting is presented. The structurally and electronically beneficial properties of the tetragonal CoSn 2 exhibit ac onsiderably low overpotential for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) on fluorinedoped tin oxide (FTO) and Ni foam (NF). Loss of Sn from the crystal lattices and oxidation of Co under strongly alkaline conditions furnishes highly disordered amorphous active CoO x (H), the catalytically active structure for OER. The Co 0 atoms in the CoSn 2 act as active sites for HER and the presence of Sn provides efficient electrical conductivity.T his intermetallic phase is an ovel type of cost-effective and competitive bifunctional electrocatalysts and predestinated for overall water-splitting devices:At wo-electrode electrolyzer with CoSn 2 on NF delivers ac ell voltage of merely 1.55 Va t 10 mA cm À2 maintaining long-term stability.Intermetallic nanocrystals are considered to be an important class of nanomaterials in the field of superconductivity, ferromagnetism, thermoelectricity,s hape-memory effects, and catalysis owing to their intriguing chemical and physical properties. [1] Recently,i ntermetallic compounds have gained enormous attention in heterogeneous catalysis by virtue of their unusual and attractive crystallographic and electronic properties. [2] It has been shown that the extent of atomic ordering and the relative concentration of both metals drastically influence the overall reactivity efficiency. The recent development of structurally ordered intermetallic materials based on noble metals (Pt, Pd) and early transition metals (Fe, Co,N i) have been successfully used for efficient oxygen reduction reaction (ORR) and HER. Intermetallic compounds containing non-noble metals (main group and transition metals) were also shown to be potential candidates for application in data storage,m agnetic materials,e lectronics,a nd sensors to electrodes in rechargeable batteries. [3] However,t he geometric and electronic influence of such materials for the energy conversion and storage applications are still scarcely investigated.As acentral part for asustainable realization of renewable energy conversion, the development of inexpensive materials for technologies capable of electrochemical water-splitting into hydrogen and oxygen in an economically viable way is highly desired. [4] Currently,n oble-metal-based materials (Pt, RuO 2, and IrO 2 )have been considered as the state-of-the-art electrocatalysts for HER and OER;however,relatively high costs and scarcity of the materials greatly stint their widespread industrial applications. [5] Recently,h igh-performance bifunctional OER and HER electrocatalysts based on nonnoble transition-metal oxides/hydroxides, [6] carbonate/ hydroxides, [7] chalcogenides, [8] phosphides, [9] borides, [10] phosphates, [11] and phosphite [12] functioning in ac ommon elect...
Core-shell nanoparticles provide a unique morphology to exploit electronic interactions between dissimilar materials conferring them new or improved functionalities. MoS2 is a layered transitionmetal disulfide that has been studied extensively for the hydrogen evolution reaction (HER) but still suffers from low electrocatalytic activity due to its poor electronic conductivity. To understand the fundamental aspects of the MoS2-Au hybrids with regard to their electrocatalytic activity, a single to a few layers of MoS2 were deposited over Au nanoparticles via a versatile procedure that allows for complete encapsulation of Au nanoparticles of arbitrary geometries. High-resolution transmission electron microscopy of the Au@MoS2 nanoparticles provides direct evidence of the core-shell morphology and also reveals the presence of morphological defects and irregularities in the MoS2 shell that are known to be more active for HER than the pristine MoS2 basal plane.Electrochemical measurements show a significant improvement in the HER activity of Au@MoS2 nanoparticles relative to free-standing MoS2 or Au-decorated MoS2. The best electrochemical performance was demonstrated by the Au nanostars -the largest Au core employed hereencapsulated in an MoS2 shell. Density-functional theory calculations show that charge transfer occurs from the Au to the MoS2 layers, producing a more conductive catalyst layer and a better electrode for electrochemical HER. The strategies to further improve the catalytic properties of such hybrid nanoparticles are discussed.
30 receptors in waiting position: In the porous (pentagon)(12)(linker)(30)-type molybdenum oxide capsule (see picture), the 30 positively charged linkers (five unsaturated shown for illustration in green, the others contain CO(3)(2-) ligands) can act as receptors for neutral and negatively charged ligands. Bubbling CO(2) into the solution containing the acetate-type capsules leads to the upload of CO(2) based on 30 coordinated CO(3)(2-) ligands.
Distinguished hybrid clusters with hydrophilic and hydrophobic interiors embedded within cationic surfactant shells are spontaneously inserted into lipid bilayers, showing well-defined ionic conductance behaviors. The transport via the narrow pore gates acting as selectivity filters is controlled by the dehydration energy of the cations.
The colourless crystals of (PPh ) [PW O ]⋅3 C H NO (1) are converted to the dark blue crystals of {(PPh ) [PW O ]⋅3C H NO} {(PPh ) (C H NO) [PW W O ] ⋅2C H NO)} (2) upon irradiation with visible light in an interesting single crystal to single crystal transformation. This photochromic conversion is accompanied by the reduction of concerned Keggin anion from {PW } to {PW W }. This redox conversion is characterized by various spectroscopic techniques including single crystal X-ray diffraction studies. The photochromic properties of compound 1 can be controlled reversibly through the dimethylformamide (DMF) molecule as a function of temperature and proton exposure in a gas-solid reaction. The present work can be described as a new concept of programmable photochromism with the formation of photochromic pockets in crystalline 1 host (solid state), wherein a solvent can be plugged at a time to show light induced coloration.
The synthesis of structurally ordered non‐noble intermetallic cobalt stannide (CoSn2) nanocrystals and their utilization for high‐performance electrocatalytic overall water‐splitting is presented. The structurally and electronically beneficial properties of the tetragonal CoSn2 exhibit a considerably low overpotential for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) on fluorine‐doped tin oxide (FTO) and Ni foam (NF). Loss of Sn from the crystal lattices and oxidation of Co under strongly alkaline conditions furnishes highly disordered amorphous active CoOx(H), the catalytically active structure for OER. The Co0 atoms in the CoSn2 act as active sites for HER and the presence of Sn provides efficient electrical conductivity. This intermetallic phase is a novel type of cost‐effective and competitive bifunctional electrocatalysts and predestinated for overall water‐splitting devices: A two‐electrode electrolyzer with CoSn2 on NF delivers a cell voltage of merely 1.55 V at 10 mA cm−2 maintaining long‐term stability.
The mechanism for the hydration of CO2 within a Keplerate nanocapsule is presented. A network of hydrogen bonds across the water layers in the first metal coordination sphere facilitates the proton abstraction and nucleophilic addition of water. The highly acidic properties of the polyoxometalate cluster are crucial for explaining the catalysed hydration.
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