FeNiS-A Potent Bifunctional Efficient Electrocatalyst for the Overall Electrochemical Water Splitting in Alkaline Electrolyte.

For a carbon-neutral society, the production of hydrogen as a clean fuel through water electrolysis is currently of great interest. Since water electrolysis is a laborious energetic reaction, it requires high energy to maintain efficient and sustainable production of hydrogen. Catalytic electrodes can reduce the required energy and minimize production costs.

Trimetallic Pentlandites (Fe,Co,Ni)S for the Electrocatalytical HER in Acidic Media.

Recently, pentlandite materials have been shown to exhibit promising properties with respect to the hydrogen evolution reaction (HER). A whole series of trimetallic FeCoNi-pentlandite materials and composites have been synthesized from the elements using high-temperature synthesis and categorized in terms of purity. Furthermore, the electrocatalytic properties regarding the HER were determined and correlated to hydrogen adsorption energies, which were determined by means of density functional theory (DFT) calculations.

Boosting the overall electrochemical water splitting performance of pentlandites through non-metallic heteroatom incorporation.

We report on synthesis of the heterotrimetallic pentlandite-type material FeCoNiS (FCNS) in presence of suitable phosphorus-(FCNSP) and nitrogen-(FCNSN) donors for the overall electrochemical water splitting. Throughout the experiments, a preferential incorporation of N into the FCNS-lattice is observed whereas the addition of phosphorus generally leads to metal-phosphate-FCNS composites. The obtained FCNSP, FCNSN, and FCNSNP facilitate the oxygen evolution reaction (OER) at 100 mAcm in 1.

Sustainable and rapid preparation of nanosized Fe/Ni-pentlandite particles by mechanochemistry.

In recent years, metal-rich sulfides of the pentlandite type (MS) have attracted considerable attention for energy storage applications. However, common synthetic routes towards pentlandites either involve energy intensive high temperature procedures or solvothermal methods with specialized precursors and non-sustainable organic solvents. Herein, we demonstrate that ball milling is a simple and efficient method to synthesize nanosized bimetallic pentlandite particles (FeNiS, Pn) with an average size of 250 nm in a single synthetic step from elemental- or sulfidic mixtures.

Enhancing the CO Electroreduction of Fe/Ni-Pentlandite Catalysts by S/Se Exchange.

The electrochemical reduction of CO is an attractive strategy towards the mitigation of environmental pollution and production of bulk chemicals as well as fuels by renewables. The bimetallic sulfide Fe Ni S (pentlandite) was recently reported as a cheap and robust catalyst for electrochemical water splitting, as well as for CO reduction with a solvent-dependent product selectivity. Inspired by numerous reports on monometallic sulfoselenides and selenides revealing higher catalytic activity for the CO reduction reaction (CO RR) than their sulfide counterparts, the authors investigated the influence of stepwise S/Se exchange in seleno-pentlandites Fe Ni S Se (Y=1-5) and their ability to act as CO reducing catalysts.

Accessing different binding sites of a multifunctional molecule: IR spectroscopy of propargyl alcoholwater complexes in helium droplets.

We report high-resolution infrared spectroscopic studies on complexes of propargyl alcohol with water (D2O) molecules, formed in superfluid helium droplets. The spectra were recorded in the frequency ranges of 2605-2700 cm-1 and 2730-2820 cm-1, covering the symmetric and antisymmetric stretching vibrations of the bound D2O. Mass-selective infrared spectroscopic measurements, a variation of the band intensities with dopant partial pressures (pickup curves) and ab initio calculations, performed at the MP2/6-311++G(d,p) level of theory, reveal the formation of two local minimum structures for the 1 : 1 PAD2O cluster.

Seleno-analogues of pentlandites (FeNiSSe, Y = 1-6): tuning bulk Fe/Ni sulphoselenides for hydrogen evolution.

We herein present a series of hitherto unprecedented seleno-pentlandites (Fe4.5Ni4.5S8-YSeY).

FeNiS (x = 3-6) as potential photocatalysts for solar-driven hydrogen production?

The efficient reduction of protons by non-noble metals under mild conditions is a challenge for our modern society. Nature utilises hydrogenases, enzymatic machineries that comprise iron- and nickel- containing active sites, to perform the conversion of protons to hydrogen. We herein report a straightforward synthetic pathway towards well-defined particles of the bio-inspired material FexNi9-xS8, a structural and functional analogue of hydrogenase metal sulfur clusters.

Bio-inspired design: bulk iron-nickel sulfide allows for efficient solvent-dependent CO reduction.

The electrocatalytic reduction of carbon dioxide (CORR) to valuable bulk chemicals is set to become a vital factor in the prevention of environmental pollution and the selective storage of sustainable energy. Inspired by structural analogues to the active site of the enzyme CODH, we envisioned that bulk Fe/Ni sulfides would enable the efficient reduction of CO. By careful adjustment of the process conditions, we demonstrate that pentlandite (FeNiS) electrodes, in addition to HER, also support the CORR reaching a peak faradaic efficiency of 87% and 13% for the formation of CO and methane, respectively at 3 mA cm.

Local Surface Structure and Composition Control the Hydrogen Evolution Reaction on Iron Nickel Sulfides.

In order to design more powerful electrocatalysts, developing our understanding of the role of the surface structure and composition of widely abundant bulk materials is crucial. This is particularly true in the search for alternative hydrogen evolution reaction (HER) catalysts to replace platinum. We report scanning electrochemical cell microscopy (SECCM) measurements of the (111)-crystal planes of Fe Ni S , a highly active HER catalyst.

Operando Phonon Studies of the Protonation Mechanism in Highly Active Hydrogen Evolution Reaction Pentlandite Catalysts.

Synthetic pentlandite (FeNiS) is a promising electrocatalyst for hydrogen evolution, demonstrating high current densities, low overpotential, and remarkable stability in bulk form. The depletion of sulfur from the surface of this catalyst during the electrochemical reaction has been proposed to be beneficial for its catalytic performance, but the role of sulfur vacancies and the mechanism determining the reaction kinetics are still unknown. We have performed electrochemical operando studies of the vibrational dynamics of pentlandite under hydrogen evolution reaction conditions using Fe nuclear resonant inelastic X-ray scattering.

Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications.

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements.