Hydrogen adsorption on various transition metal (111) surfaces in water: a DFT forecast.

The hydrogen adsorption and hydrogen evolution at the M(111), (M = Ag, Au Cu, Pt, Pd, Ni & Co) surfaces of various transition metals in aqueous suspensions were studied computationally using the DFT methods. The hydrogens are adsorbed dissociatively on all surfaces except on Ag(111) and Au(111) surfaces. The results are validated by reported experimental and computational studies.

The Competition between 4-Nitrophenol Reduction and BH Hydrolysis on Metal Nanoparticle Catalysts.

Assessing competitive environmental catalytic reduction processes via NaBH is essential, as BH is both an energy carrier (as H) and a reducing agent. A comprehensive catalytic study of the competition between the borohydride hydrolysis reaction (BHR, releasing H) and 4-nitrophenol reduction via BH on M- and M/M' (alloy)-nanoparticle catalysts is reported. The results reveal an inverse correlation between the catalytic efficiency for BH hydrolysis and 4-nitrophenol reduction, indicating that catalysts performing well in one process exhibit lower activity in the other.

Chemically Etched Prussian Blue Analog-WS Composite as a Precatalyst for Enhanced Electrocatalytic Water Oxidation in Alkaline Media.

The electrochemical water-splitting reaction is a promising source of ecofriendly hydrogen fuel. However, the oxygen evolution reaction (OER) at the anode impedes the overall process due to its four-electron oxidation steps. To address this issue, we developed a highly efficient and cost-effective electrocatalyst by transforming Co-Fe Prussian blue analog nanocubes into hollow nanocages using dimethylformamide as a mild etchant and then anchoring tungsten disulfide (WS) nanoflowers onto the cages to boost OER efficiency.

Enhancing the catalytic OER performance of MoS Fe and Co doping.

Enhancing the sluggish kinetics of the electrochemical oxygen evolution reaction (OER) is crucial for many clean-energy production technologies. Although much progress has been made in recent years, developing active, stable, and cost-effective OER electrocatalysts is still challenging. The layered MoS, based on Earth-abundant elements, is widely explored as a promising hydrogen evolution electrocatalyst but exhibits poor OER activity.

W Doping in NiP as a Platform to Enhance Overall Electrochemical Water Splitting.

Bifunctional electrocatalysts for efficient hydrogen generation from water splitting must overcome both the sluggish water dissociation step of the alkaline hydrogen evolution half-reaction (HER) and the kinetic barrier of the anodic oxygen evolution half-reaction (OER). Nickel phosphides are a promising catalysts family and are known to develop a thin active layer of oxidized Ni in an alkaline medium. Here, NiP was recognized as a suitable platform for the electrochemical production of γ-NiOOH─a particularly active phase─because of its matching crystallographic structure.

The Role of Common Alcoholic Sacrificial Agents in Photocatalysis: Is It Always Trivial?

Photocatalytic hydrogen production is proposed as a sustainable energy source. Simultaneous reduction and oxidation of water is a complex multistep reaction with high overpotential. Photocatalytic processes involving semiconductors transfer electrons from the valence band to the conduction band.

Radicals in 'biologically relevant' concentrations behave differently: Uncovering new radical reactions following the reaction of hydroxyl radicals with DMSO.

Methyl radicals play key roles in various chemical and biological processes. Mechanistic studies of methyl radicals with their precursor, Dimethyl Sulfoxide (DMSO), were extensively studied. Though the involved mechanisms seemed to be clarified, essentially none of the studies have been performed at conditions relevant to both biological and catalytic systems, i.

New insights into HER catalysis: the effect of nano-silica support on catalysis by silver nanoparticles.

Supported metal catalysts have recently attracted considerable attention in the field of catalysis. The effect of surface chemical groups (SiO/SiOH) on SiO-Ag-NPs along with the average negative charge induced by (CH)COH˙ radicals on the catalytic reduction of HO/HO towards the hydrogen evolution reaction (HER) is reported. The results indicate that similar effects are observed both above and below the point of zero charge (PZC) of silica.

Manganese Doping of MoSe Promotes Active Defect Sites for Hydrogen Evolution.

Transition-metal dichalcogenides (TMDs) are being widely pursued as inexpensive, earth-abundant substitutes for precious-metal catalysts in technologically important reactions such as electrochemical hydrogen evolution reaction (HER). However, the relatively high onset potentials of TMDs relative to Pt remain a persistent challenge in widespread adoption of these materials. Here, we demonstrate a one-pot synthesis approach for substitutional Mn-doping of MoSe nanoflowers to achieve appreciable reduction in the overpotential for HER along with a substantial improvement in the charge-transfer kinetics.

The Chemical Properties of Hydrogen Atoms Adsorbed on M -Nanoparticles Suspended in Aqueous Solutions: The Case of Ag -NPs and Au -NPs Reduced by BD.

The nature of H-atoms adsorbed on M -nanoparticles is of major importance in many catalyzed reduction processes. Using isotope labeling, we determined that hydrogen evolution from transient {(M -NP)-H } proceeds mainly via the Heyrovsky mechanism when n is large (i.e.

Enhancing the catalytic activity of the alkaline hydrogen evolution reaction by tuning the S/Se ratio in the Mo(SSe) catalyst.

The alkaline hydrogen evolution reaction (HER) plays a key role in photo(electro)catalytic water splitting technologies, particularly in water-alkali electrolyzers. Unfortunately, although transition metal dichalcogenide (TMD) materials, especially MoS2 and MoSe2, are considered efficient, Earth-abundant catalysts for the HER in an acidic electrolyte, they are much less effective under high pH conditions due to a sluggish water dissociation process (Volmer-step) and strong adsorption of the OH- intermediate on their surfaces. Herein we show a novel synergetic effect obtained by tailoring the S/Se ratio in Mo(SxSe1-x)2 alloys.

Improved catalytic activity of MoWSe alloy nanoflowers promotes efficient hydrogen evolution reaction in both acidic and alkaline aqueous solutions.

Layered transition metal dichalcogenides are noble-metal free electrocatalysts for the hydrogen evolution reaction (HER). Instead of using the common hydrothermal synthesis, which requires high pressure and temperature, herein a relatively simple and controlled colloidal synthesis was used to produce an alloy of MoWSe with nanoflower morphology as a model system for the electrocatalysis of hydrogen evolution in both acidic and alkaline environments. The results show that MoWSe alloys exhibit better catalytic activity in both acidic and alkaline solutions with low overpotentials compared to pure MoSe and WSe.

Coating Platinum Nanoparticles with Methyl Radicals: Effects on Properties and Catalytic Implications.

It was recently reported that the reaction of methyl radicals with Pt(0) nanoparticles (NPs), prepared by the reduction of Pt(SO4)2 with NaBH4, is fast and yields as the major product stable (Pt(0)-NPs)-(CH3)n and as side products, in low yields, C2H6, C2H4, and some oligomers. We decided to study the effect of this coating on the properties of the Pt(0)-NPs. The results show that the coating can cover up to 75% of the surface Pt(0) atoms.

H/D kinetic isotope effect as a tool to elucidate the reaction mechanism of methyl radicals with glycine in aqueous solutions.

The H/D kinetic isotope effect (KIE) for the reaction of methyl radicals with glycine in aqueous solutions at pH 10.6 equals 16 ± 3. This result proves that the methyl radical abstracts a hydrogen atom from the methylene group of glycine and not an electron from the unpaired couple on the nitrogen atom.

On the lifetime of the transients (NP)-(CH3)n (NP = Ag0, Au0, TiO2 nanoparticles) formed in the reactions between methyl radicals and nanoparticles suspended in aqueous solutions.

Methyl radicals react in fast reactions, with rate constants k>1×10(8)  M(-1)  s(-1), with Au(0), Ag(0) and TiO(2) nanoparticles (NPs) dispersed in aqueous solutions to form intermediates, (NP)-(CH(3))(n), in which the methyl groups are covalently bound to the NPs. These intermediates decompose to form ethane. As n≥2 is required for the formation of C(2)H(6), the minimal lifetime (τ) of the methyls bound to the NPs, (NP)-CH(3), can be estimated from the rate of production of the CH(3)(·) radicals and the NPs concentration.

On the reactions of methyl radicals with TiO2 nanoparticles and granular powders immersed in aqueous solutions.

Methyl radicals react with TiO(2) nanoparticles (NPs) immersed in aqueous solutions to form transients in which the methyls are covalently bound to the particles. The rate constant for this reaction approaches the diffusion-controlled limit and increases somewhat with the number of methyls bound to the particle. The transients decompose to yield ethane.