First-row transition metal carbonates catalyze the electrochemical oxygen evolution reaction: iron is master of them all.

In pursuing green hydrogen fuel, electrochemical water-splitting emerges as the optimal method. A critical challenge in advancing this process is identifying a cost-effective electrocatalyst for oxygen evolution on the anode. Recent research has demonstrated the efficacy of first-row transition metal carbonates as catalysts for various oxidation reactions.

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.

Electrochemical degradation of per- and poly-fluoroalkyl substances in the presence of natural organic matter.

Per- and poly-fluoroalkyl substances (PFAS), a contentious group of highly fluorinated, persistent, and potentially toxic chemicals, have been associated with human health risks. Currently, treatment processes that destroy PFAS are challenged by transforming these contaminants into additional toxic substances that may have unknown impacts on human health and the environment. Electrochemical oxidation (EO) is a promising method for scissoring long-chain PFAS, especially in the presence of natural organic matter (NOM), which interferes with most other treatment approaches used to degrade PFAS.

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.

DFT Study of the BH Hydrolysis on Au(111) Surface.

The mechanism of the catalytic hydrolysis of BH on Au(111) as studied by DFT is reported. The results are compared to the analogous process on Ag(111) that was recently reported. It is found that the borohydride species are adsorbed stronger on the Au -NP surface than on the Ag -NP surface.

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.

Redox Properties of CeDOTA in Carbonated Aqueous Solutions. A Radiolytic and an Electrochemical Study.

The redox chemistry of CeDOTA in carbonate solutions was studied using electrochemistry and radiolysis techniques (continuous radiolysis and pulse radiolysis). Spectroscopic measurements point out that the species present in the solutions at high bicarbonate concentrations are [CeDOTA(CO)] (or less plausible [CeDOTA(HCO)]) with the carbonate (bicarbonate) anion as the ninth ligand versus [CeDOTA(HO)] present in the absence of bicarbonate. Electrochemical results show a relatively low increase in the thermodynamic stabilization of the redox couple Ce in the presence of carbonate versus its aqueous analogue.

NO and SO Flue Gas Treatment System Based on Sulfur-Enriched Organic Oil in Water Emulsion.

Nitrogen (NO ) and sulfur (SO ) oxides, the major gaseous pollutants emitted from fossil fuel combustion, have significant health and environmental concerns. Environmental regulations limit these pollutant emissions to tolerable levels. Currently, these pollutants are treated by flue gas desulfurization (SO removal) and selective catalytic reduction (NO removal) processes.

On the Differences in the Mechanisms of Reduction of AuCl and Ag(HO) with BH.

The mechanism of reduction of AuCl/AuClOH by BH was analyzed by density functional theory (DFT). The results point out that Au are not intermediates in the process. The derived mechanism differs considerably from that reported for the analogous process involving the reduction of Ag(HO) by BH.

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.

On the mechanism of reduction of M(HO) by borohydride: the case of Ag(HO).

The redox potentials of M(H2O)mn+/M0(atom) couples are often far too negative to enable the formation of M0(atom) by most reducing agents. Therefore, one has to reconsider the mechanism of formation of M0-NPs by the bottom-up procedure. A deep and detailed theoretical analysis of the reduction of Ag(H2O)2+ by BH4- points out that silver cations act mainly as catalysts of the reactions BH4- + 4H2O → B(OH)4- + 4H2.

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.

Water oxidation catalyzed by cobalt(II) adsorbed on silica nanoparticles.

A novel, highly efficient, and stable water oxidation catalyst was prepared by a pH-controlled adsorption of Co(II) on ~10 nm diameter silica nanoparticles. A lower limit of ~300 s(-1) per cobalt atom for the catalyst turnover frequency in oxygen evolution was estimated, which attests to a very high catalytic activity. Electron microscopy revealed that cobalt is adsorbed on the SiO(2) nanoparticle surfaces as small (1-2 nm) clusters of Co(OH)(2).

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.

Photochemical induced growth and aggregation of metal nanoparticles in diode-array spectrophotometer via excited dimethyl-sulfoxide.

Ag(0) and Au(0) nanoparticles suspended in dilute aqueous solutions containing (CH(3))(2)SO are photochemically unstable. The light source of a diode-array spectrophotometer induces, within less than a minute, particle growth and aggregation. The results indicate that this process is triggered by UV light absorption by the (CH(3))(2)SO.

Reactions of alkyl-radicals with gold and silver nanoparticles in aqueous solutions.

Silver and gold nanoparticles are very efficient catalysts for the dimerization of methyl-radicals in aqueous solutions. The rate constants for the reaction of methyl-radicals with the gold and silver nanoparticles were measured and found to be 3.7 x 10(8) M(-1) s(-1) and 1.