Synthesis of an imine-type nickel complex and investigation of its electrocatalytic activity for H evolution.

We report on the synthesis and characterization of an imine-type nickel complex produced the complexation of an generated 2-(iminomethyl)phenol ligand with Ni ion. The use of this complex as an electrocatalyst for H evolution in a DMF solution, with acetic acid as the proton source, was investigated in detail, employing both experimental analyses (electrochemical analysis, spectroscopy analysis) and theoretical analysis (plateau current analysis). The overpotential required for H evolution is about 590 mV with a faradaic efficiency of 49% after 3 hours bulk electrolysis, competing with the two-electron reduction of free-imine groups in the ligand.

Achieving Excellent H Evolution Activity of Silver Nanocatalyst by a Simple Electrochemical Treatment Process.

Silver nanoparticles (AgNPs) were synthesized in an aqueous solution via the reduction of AgNO employing citrate reducing agent. The resultant AgNPs were first assayed for the catalytic H evolution in an acidic electrolyte, namely pH 0.3 HSO solution, showing negligible activity.

A novel method for preparing BiOI nanoplates and their use as precursors to synthesize porous BiVO water oxidation photocatalysts.

In this work, we report an innovative method for synthesizing BiOI nanoplate powder by a slow basification of an aqueous solution constituted of Bi(NO) and KI. The basification was done with NH vapor which was naturally generated on top of an NHOH solution kept in a closed space. The impact of the basification rate on the morphology and crystallinity of the BiOI product was investigated.

Fabrication of inverse opal molybdenum sulfide and its use as a catalyst for H evolution.

Amorphous molybdenum sulfide (MoS) and crystalline molybdenum disulfide (MoS) are attractive noble-metal-free electrocatalysts for the H evolution reaction from water. Their actual activities depend on the quantity of active sites which are exposed to the electrolyte, which in turn, is influenced by their specific electrochemical surface area. Herein we report on the fabrication of regular inverse opal MoS and MoS films by employing polystyrene nanoparticles with diameters in the range of 30-90 nm as hard templates.

[Mo S ] Complex as a Precursor for In-situ Generation of Molybdenum Sulfide Catalyst During the H Evolution.

For decades, the sulfido molybdenum complexes like [MoS ] , [Mo S ] , [Mo S ] have gained great attention because of their chemical versatility as well as their structural similarity to the edge-plan of the molybdenum disulfide (MoS ) which shows promising catalytic ability for the H generation. In this work, we report on the investigation of the dinuclear complex [Mo S ] in both organic and aqueous solution. We demonstrate that [Mo S ] is not intact during the H evolution catalysis when it is assayed as a homogeneous catalyst in an electrolyte solution (e.

Exploring the Sub-nanoscale Structure of Cobalt Molybdenum Sulfide and the Role of a Cobalt Promoter in Catalytic Hydrogen Evolution.

Cobalt-promoted molybdenum sulfide (CoMoS) is known as a promising catalyst for H evolution reaction and hydrogen desulfurization reaction. This material exhibits superior catalytic activity as compared to its pristine molybdenum sulfide counterpart. However, revealing the actual structure of cobalt-promoted molybdenum sulfide as well as the plausible contribution of a cobalt promoter is still challenging, especially when the material has an amorphous nature.

Crystallization Pathways and Evolution of Morphologies and Structural Defects of α-MnO under Air Annealing.

Manganese dioxide nanomaterials have wide applications in many areas from catalysis and Li-ion batteries to gas sensing. Understanding the crystallization pathways, morphologies, and formation of defects in their structure is particularly important but still a challenging issue. Herein, we employed an arsenal of X-ray diffraction (XRD), scanning electron microscopy (SEM), neutron diffraction, positron annihilation spectroscopies, and calculations to investigate the evolution of the morphology and structure of α-MnO nanomaterials prepared via reduction of KMnO solution with CHOH prior to being annealed in air at 200-600 °C.

Electrocatalytic H evolution using binuclear cobalt complexes as catalysts.

We report herein on the use of two binuclear cobalt complexes with the ,'-bis(salicylidene)-phenylmethanediamine ligand as catalysts for the H evolution in DMF solution with acetic acid as proton source. Both experimental analyses (electrochemical analysis, spectroscopy analysis) and theoretical analysis (foot-of-the wave analysis) were employed. These catalysts required an overpotential of 470 mV to catalyze the H evolution and generated H gas with a faradaic efficiency of 85-95% as calculated on the basis of after 5 hour bulk electrolysis.

Synthesis of NiFeOx nanocatalysts from metal-organic precursors for the oxygen evolution reaction.

Production of hydrogen from a renewable source that is water requires the development of sustainable catalytic processes. This implies, among others, developing efficient catalytic materials from abundant and low-cost resources and investigating their performance, especially in the oxidation of water as this half-reaction is the bottleneck of the water splitting process. For this purpose, NiFe-based nanoparticles with sizes .

Water-Splitting Artificial Leaf Based on a Triple-Junction Silicon Solar Cell: One-Step Fabrication through Photoinduced Deposition of Catalysts and Electrochemical Operando Monitoring.

Solar hydrogen generation via water splitting using a monolithic photoelectrochemical cell, also called artificial leaf, could be a powerful technology to accelerate the transition from fossil to sustainable energy sources. Identification of scalable methods for the fabrication of monolithic devices and gaining insights into their operating mode to identify solutions to improve performance and stability represent great challenges. Herein, we report on the one-step fabrication of a CoWO|ITO|3jn-a-Si|Steel|CoWS monolithic device via the simple photoinduced deposition of CoWO and CoWS as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalyst layers, respectively, onto an illuminated ITO|3jn-a-Si|Steel solar cell using a single-deposition bath containing the [Co(WS)] complex.

Covalent Grafting of Ruthenium Complexes on Iron Oxide Nanoparticles: Hybrid Materials for Photocatalytic Water Oxidation.

The present environmental crisis prompts the search for renewable energy sources such as solar-driven production of hydrogen from water. Herein, we report an efficient hybrid photocatalyst for water oxidation, consisting of a ruthenium polypyridyl complex covalently grafted on core/shell nanoparticles a phosphonic acid group. The photoelectrochemical measurements were performed under 1 sun illumination in 1 M KOH.

Highly porous Co-doped NiO nanorods: facile hydrothermal synthesis and electrocatalytic oxygen evolution properties.

Highly porous 3d transition metal oxide nanostructures are opening up the exciting area of oxygen evolution reaction (OER) catalysts in alkaline medium thanks to their good thermal and chemical stability, excellent physiochemical properties, high specific surface area and abundant nanopores. In this paper, highly porous Co-doped NiO nanorods were successfully synthesized by a simple hydrothermal method. The porous rod-like nanostructures were preserved with the added cobalt dopant ranging from 1 to 5 at% but were broken into aggregated nanoparticles at higher concentrations of additional cobalt.

Effects of CO and temperature on phytolith dissolution.

Phytoliths, silica structures derived from plant residues in silicon (Si)-accumulating plant species, have recently been recognized as a sink and source of nutrients and a hosting phase for carbon sequestration in soil. While the solubility of phytoliths in relation to their respective nature and solution chemistry has been intensively studied, the combined effects of CO and temperature, two highly variable parameters in soil, have not been fully understood. We hypothesized that changes in CO and temperature may affect the dissolution rate, thereby resizing the soil phytolith pool.

Embedding Amorphous Molybdenum Sulfide within a Porous Poly(3,4-ethylenedioxythiophene) Matrix to Enhance its H -evolving Catalytic Activity and Robustness.

Amorphous molybdenum sulfide (MoS ) is a promising alternative to Pt catalyst for the H evolution in water. However, it is suffered of an electrochemical corrosion. In this report, we present a strategy to tack this issue by embedding the MoS catalyst within a porous poly(3,4-ethylenedioxythiophene) (PEDOT) matrix.

Investigation on the Growth Mechanism of Cu MoS Nanotube, Nanoplate and its use as a Catalyst for Hydrogen Evolution in Water.

Cu MoS is a ternary transition-metal sulfide that shows great potential in the field of energy conversion and storage, namely catalytic H evolution in water and Li-, Na- or Mg-ion battery. In this work, we report on a growth mechanism of the single-crystalline Cu MoS nanotube from (NH ) MoS salt and Cu O nanoparticle. By probing the nature and morphology of solid products generated in function of reaction conditions we find that the crystalline Cu(NH )MoS nanorod is first generated at ambient conditions.

Gold nanorod/molybdenum sulfide core-shell nanostructures synthesized by a photo-induced reduction process.

Coupling of plasmonic nanostructures and semiconductors gives promising hybrid nanostructures that can be used in different applications such as photosensing and energy conversion. In this report, we describe an approach for fabricating a new hybrid material by coupling a gold nanorod (Au NR) core and amorphous molybdenum sulfide (MoS) shell. The Au NR/MoS core-shell structure is achieved by exploiting the hot electrons generated in the plasmonic excitation of Au NRs to drive the reduction of [MoS], which is pre-adsorbed on the Au NR surface, producing a thin MoS layer.

Insights into the Electrochemical Polymerization of [Mo S ] Generating Amorphous Molybdenum Sulfide.

Amorphous molybdenum sulfide is an attractive electrode material for Li/Mg batteries and an efficient Pt-free catalyst for the hydrogen evolution reaction in water. By using the electrochemical quartz crystal microbalance (EQCM) analysis, new insights were gained into the electrochemical polymerization of the [Mo S ] cluster, which generates amorphous molybdenum sulfide thin films. In this work, it is shown that, at the anodic potential, a two-electron oxidative elimination of the terminal disulfide ligand within the [Mo S ] cluster induces the polymerization.

Electrodeposited Amorphous Tungsten-doped Cobalt Oxide as an Efficient Catalyst for the Oxygen Evolution Reaction.

Thin film of amorphous tungsten-doped cobalt oxide (W:CoO) was successfully grown on a conducting electrode via an electrochemical oxidation process employing a [Co(WS ) ] deposition bath. The W:CoO catalyst displays an attractive performance for the oxygen evolution reaction in an alkaline solution. In an NaOH solution of pH 13, W:CoO operates with a moderate onset overpotential of 230 mV and requires 320 mV overpotential to generate a catalytic current density of 10 mA cm .

Gold nanoparticles as an outstanding catalyst for the hydrogen evolution reaction.

An electrode made of Au nanoparticles, ca. 13 nm in diameter, displays outstanding catalytic activity for the hydrogen evolution reaction in water. At an overpotential of 200 mV it operates with a catalytic rate TOF of 0.

Novel Amorphous Molybdenum Selenide as an Efficient Catalyst for Hydrogen Evolution Reaction.

Amorphous molybdenum selenide nanopowder, obtained by refluxing Mo(CO) and Se precursors in dichlorobenzene, shows several structural and electrochemical similarities to the amorphous molybdenum sulfide analogue. The molybdenum selenide displays attractive catalytic properties for the hydrogen evolution reaction in water over a wide range of pH. In a pH 0 solution, it operates with a small onset overpotential of 125 mV and requires an overpotential of 270 mV for generating a catalytic current of 10 mA/cm.

Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid.

We report here on a new series of CO-reducing molecular catalysts based on Earth-abundant elements that are very selective for the production of formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency of 90 ± 10%) at moderate overpotentials (500-700 mV in DMF measured at the middle of the catalytic wave). The [CpCo(PN)I] compounds contain diphosphine ligands, PN, with two pendant amine residues that act as proton relays during CO-reduction catalysis and tune their activity. Four different PN ligands with cyclohexyl or phenyl substituents on phosphorus and benzyl or phenyl substituents on nitrogen were employed, and the compound with the most electron-donating phosphine ligand and the most basic amine functions performs best among the series, with turnover frequency >1000 s.

Disulfide-Bridged (Mo3S11) Cluster Polymer: Molecular Dynamics and Application as Electrode Material for a Rechargeable Magnesium Battery.

Exploring novel electrode materials is critical for the development of a next-generation rechargeable magnesium battery with high volumetric capacity. Here, we showed that a distinct amorphous molybdenum sulfide, being a coordination polymer of disulfide-bridged (Mo3S11) clusters, has great potential as a rechargeable magnesium battery cathode. This material provided good reversible capacity, attributed to its unique structure with high flexibility and capability of deformation upon Mg insertion.

Coordination polymer structure and revisited hydrogen evolution catalytic mechanism for amorphous molybdenum sulfide.

Molybdenum sulfides are very attractive noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) from water. The atomic structure and identity of the catalytically active sites have been well established for crystalline molybdenum disulfide (c-MoS2) but not for amorphous molybdenum sulfide (a-MoSx), which exhibits significantly higher HER activity compared to its crystalline counterpart. Here we show that HER-active a-MoSx, prepared either as nanoparticles or as films, is a molecular-based coordination polymer consisting of discrete [Mo3S13](2-) building blocks.