Efficient Electrocatalyst For Hydrogen Evolution Research Articles

Easily-prepared dinickel phosphide (Ni2P) nanoparticles as an efficient and robust electrocatalyst for hydrogen evolution

Polydispersed dinickel phosphide (Ni2P) nanoparticles were synthesized by a simple and scalable solid-state reaction. These nanoparticles are an excellent and robust catalyst for the electrochemical hydrogen evolution reaction, operating in both acidic and basic solutions.

Hydrogen Evolution by Tungsten Carbonitride Nanoelectrocatalysts Synthesized by the Formation of a Tungsten Acid/Polymer Hybrid In Situ

A step forward for tungsten: Nitrogen-rich tungsten carbonitride (WCN) nanomaterials can act as stable and efficient hydrogen evolution electrocatalysts with a much higher activity than conventional WCN materials. The use of a polymerization process provides a unique synthetic route to H2 WO4 nanoparticles, which can then be used to synthesize the WCN-derived catalysts.

Exfoliated MoS2 nanosheets as efficient catalysts for electrochemical hydrogen evolution

An efficient electrocatalyst for hydrogen evolution has been developed based on liquid exfoliation of bulk MoS2 via a direct dispersion and ultrasonication method. Transmission electron microscopy and atomic force microscopy measurements show that the exfoliated MoS2 consists of two-dimensional nanosheets. The exfoliated MoS2 nanosheets modified glass carbon electrode (E-MoS2/GCE) with various loadings is fabricated via a drop-casting method. The electrocatalytic activity of E-MoS2/GCE toward hydrogen evolution reaction is examined using linear sweep voltammetry. It is shown that the E-MoS2/GCE with an electrode loading of 48μgcm−2 exhibits a high catalytic activity for hydrogen evolution with a low overpotential (−0.12V) and a high current density (1.26mAcm−2, at η=150mV).

Facile synthesis of porous 3D CoNiCu nano-network structure and their activity towards hydrogen evolution reaction

Nanostructured alloys have recently attracted great attention for hydrogen evolution due to their unique electron structure and large surface area. Herein, we reported a facile electrochemical method to prepare three-dimensional (3D) nano-network structures and demonstrated their feasibility as efficient electrocatalyst for hydrogen evolution. These 3D CoNiCu nano-network structure exhibited good performance in hydrogen evolution reaction (HER).

Nanocomposite of MoS2 on ordered mesoporous carbon nanospheres: A highly active catalyst for electrochemical hydrogen evolution

An efficient electrocatalyst for hydrogen evolution has been developed based upon in situ reduction of MoS2 on ordered mesoporous carbon nanospheres (MoS2/MCNs). The properties of MoS2/MCNs were characterised by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Polarisation curves and electrochemical impedance measurements were obtained for MoS2/MCNs modified glassy carbon electrodes. The MoS2/MCNs exhibit high catalytic activity for hydrogen evolution with a low overpotential and a very high current density. A theory outlining the origins of the Tafel slope for a Volmer-Heyrovsky (rate determining step) mechanism of hydrogen evolution at MoS2 catalytic edge sites is presented.

Cobalt and nickel diimine-dioxime complexes as molecular electrocatalysts for hydrogen evolution with low overvoltages.

Hydrogen production through the reduction of water appears to be a convenient solution for the long-run storage of renewable energies. However, economically viable hydrogen production requests platinum-free catalysts, because this expensive and scarce (only 37 ppb in the Earth's crust) metal is not a sustainable resource [Gordon RB, Bertram M, Graedel TE (2006) Proc Natl Acad Sci USA 103:1209-1214]. Here, we report on a new family of cobalt and nickel diimine-dioxime complexes as efficient and stable electrocatalysts for hydrogen evolution from acidic nonaqueous solutions with slightly lower overvoltages and much larger stabilities towards hydrolysis as compared to previously reported cobaloxime catalysts. A mechanistic study allowed us to determine that hydrogen evolution likely proceeds through a bimetallic homolytic pathway. The presence of a proton-exchanging site in the ligand, furthermore, provides an exquisite mechanism for tuning the electrocatalytic potential for hydrogen evolution of these compounds in response to variations of the acidity of the solution, a feature only reported for native hydrogenase enzymes so far.

Hydrogen Oxidation and Production Using Nickel-Based Molecular Catalysts with Positioned Proton Relays

Highly efficient electrocatalysts for both hydrogen evolution and hydrogen oxidation have been designed, synthesized, and characterized. The catalysts in their resting states are air-stable, mononuclear nickel(II) complexes containing cyclic diphosphine ligands with nitrogen bases incorporated into the ligand backbone. X-ray diffraction studies have established that the cation of [Ni(P(Ph)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2), 6a, (where P(Ph)(2)N(Ph)(2) is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane) is a trigonal bipyramid with bonds to four phosphorus atoms of the two bidentate diphosphine ligands and the nitrogen atom of an acetonitrile molecule. Two of the six-membered rings formed by the diphosphine ligands and Ni have boat conformations with an average Ni- - -N distance to the two pendant bases of 3.4 A. The cation of [Ni(P(Cy)(2)N(Bz)(2))(2)](BF(4))(2), 6b, (where Cy = cyclohexyl and Bz = benzyl) is a distorted square planar complex. For 6b, all four six-membered rings formed upon coordination of the diphosphine ligands to the metal are in the boat form. In this case, the average Ni- - -N distance to the pendant base is 3.3 A. Complex 6a is an electrocatalyst for hydrogen production in acidic acetonitrile solutions, and compound 6b is an electrocatalyst for hydrogen oxidation in basic acetonitrile solutions. It is demonstrated that the high catalytic rates observed with these complexes are a result of the positioning of the nitrogen base so that it plays an important role in the formation and cleavage of the H-H bond.

Trends in the Exchange Current for Hydrogen Evolution

A density functional theory database of hydrogen chemisorption energies on close packed surfaces of a number of transition and noble metals is presented. The bond energies are used to understand the trends in the exchange current for hydrogen evolution. A volcano curve is obtained when measured exchange currents are plotted as a function of the calculated hydrogen adsorption energies and a simple kinetic model is developed to understand the origin of the volcano. The volcano curve is also consistent with Pt being the most efficient electrocatalyst for hydrogen evolution. © 2005 The Electrochemical Society. All rights reserved.

AB5-catalyzed hydrogen evolution cathodes

Abstract The AB 5 metal compounds are highly efficient hydrogen evolution electrocatalysts in alkaline electrolyte. Three types of AB 5 -catalyzed cathode structures were made, using the hydride-forming AB 5 compounds in particulate form. Plastic-bonded cathodes containing >90 w/o AB 5 (finished-weight basis) were the most efficient, giving hydrogen evolution overpotentials (ν H2 ) of about 0.05 V at 200 mA cm −2 . However, they tended to swell and shed material during electrolysis. Pressed, sintered cathodes containing 40–70 w/o catalyst in a nickel binder gave ν H2 ∼ 0.08 V; catalyst retention was excellent. Porous, sintered cathode coatings were made with 30–70 w/o AB 5 catalyst loadings. Their overpotentials were similar to those of the pressed, sintered cathodes. However, at catalyst loadings below about 40 w/o, high overpotentials characteristic of the nickel binder were observed. The structural and electrochemical properties of the three AB 5 -catalyzed cathodes are discussed.