Construction of Ternary ZnCuCoO Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High-Energy-Density Asymmetric Supercapacitor Application.

Developing nanostructured multi-transition metal-based spinel architectures represents a strategic approach for boosting the energy density of supercapacitors while preserving high power density. Here, the influence of incorporating Zn and Cu into CoO spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, CoO), binary (ZnCoO, CuCoO), and ternary (ZnCuCoO) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower-like structures of ZnCuCoO, comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics.

Experimental and Theoretical Insights of Anion Regulation in MOF-Derived Ni-Co-Based Nanosheets for Supercapacitors and Anion Exchange Membrane Water Electrolyzers.

The anionic components have a significant role in regulating the electrochemical properties of mixed transition-metal (MTM)-based materials. However, the relationship between the anionic components and their inherent electrochemical properties in MTM-based materials is still unclear. Herein, we report the anion-dependent supercapacitive and oxygen evolution reaction (OER) properties of in situ grown binary Ni-Co-selenide (Se)/sulfide (S)/phosphide (P) nanosheet arrays (NAs) over nickel foam starting from MOF-derived Ni-Co layered double hydroxide precursors.

Morphology-dependent adsorption energetics of Ru nanoparticles on hcp-boron nitride (001) surface - a first-principles study.

Active B-sites on Ru catalysts can be exploited for various catalytic applications; in particular, the epitaxial formation of Ru nanoparticles with hexagonal planar morphologies on hexagonal boron nitride sheets increases the number of active B-sites along the nanoparticle edges. The energetics of adsorption of Ru nanoparticles on hexagonal boron nitride were investigated using density functional theory calculations. Then, to understand the fundamental reason for this morphology control, adsorption studies and charge density analysis were performed on fcc and hcp Ru nanoparticles heteroepitaxially formed on a hexagonal boron nitride support.

Unveiling the positive effect of mineral induced natural organic matter (NOM) on catalyst properties and catalytic dechlorination performance: An experiment and DFT study.

Herein, we report the significant effects of natural organic matter contained in natural zeolite (Z-NOM) on the physicochemical characteristics of a Ni/Fe@natural zeolite (NF@NZ) catalyst and its decontamination performance toward the dechlorination of trichloroethylene (TCE). Z-NOM predominantly consists of humic-like substances and has demonstrable utility in the synthesis of bimetallic catalysts. Compared to NF@NZ (devoid of Z-NOM), NF@NZ had increased dispersibility and mobility and showed significant enhancement in the catalytic dechlorination of TCE owing to the encapsulation of Ni/Fe nanoparticles by Z-NOM.

Heteroepitaxial Growth of B -Site-Rich Ru Nanoparticles Guided by Hexagonal Boron Nitride for Low-Temperature Ammonia Dehydrogenation.

Ruthenium is one of the most active catalysts for ammonia dehydrogenation and is essential for the use of ammonia as a hydrogen storage material. The B -type site on the surface of ruthenium is expected to exhibit the highest catalytic activity for ammonia dehydrogenation, but the number of these sites is typically low. Here, a B -site-rich ruthenium catalyst is synthesized by exploiting the crystal symmetry of a hexagonal boron nitride support.

Controlled syngas production by electrocatalytic CO reduction on formulated Au(SR) and PtAu(SR) nanoclusters.

Syngas, a gaseous mixture of CO and H, is a critical industrial feedstock for producing bulk chemicals and synthetic fuels, and its production via direct CO electroreduction in aqueous media constitutes an important step toward carbon-negative technologies. Herein, we report controlled syngas production with various H/CO ratios via the electrochemical CO reduction reaction (CORR) on specifically formulated Au and PtAu nanoclusters (NCs) with core-atom-controlled selectivities. While CO was predominantly produced from the CORR on the Au NCs, H production was favored on the PtAu NCs.

Formic acid dehydrogenation over PdNi alloys supported on N-doped carbon: synergistic effect of Pd-Ni alloying on hydrogen release.

Bimetallic PdNi alloys supported on nitrogen-doped carbon (PdNi/N-C, x = 0.37, 1.3 and 3.

Mobility of multiple heavy metalloids in contaminated soil under various redox conditions: Effects of iron sulfide presence and phosphate competition.

The mobility of heavy metalloids including As, Sb, Mo, W, and Cr in soil was investigated under both reducing and oxidizing conditions. The effects of soil mineralogy and the presence of competitive anions were studied as important factors affecting the mobility of these contaminants. Batch experiments conducted with the addition of oxidized and fresh FeS exhibited enhanced sorption rates for As and W under oxidizing conditions, and for Mo under reducing conditions.

Hierarchical cobalt-nitride and -oxide co-doped porous carbon nanostructures for highly efficient and durable bifunctional oxygen reaction electrocatalysts.

Here we report the preparation of hollow microspheres with a thin shell composed of mixed cobalt nitride (Co-N) and cobalt oxide (Co-O) nanofragments encapsulated in thin layers of nitrogen-doped carbon (N-C) nanostructure (Co-N/Co-O@N-C) arrays with enhanced bifunctional oxygen electrochemical performance. The hybrid structures are synthesized via heat treatment of N-doped hollow carbon microspheres with cobalt nitrate, and both the specific ratio of these precursors and the selected annealing temperature are found to be the key factors for the formation of the unique hybrid structure. The as-obtained product (Co-N/Co-O@N-C) presents a large specific surface area (493 m g), high-level heteroatom doping (Co-N, Co-O, and N-C), and hierarchical porous nanoarchitecture containing macroporous frameworks and mesoporous walls.

Transition metal alloying effect on the phosphoric acid adsorption strength of Pt nanoparticles: an experimental and density functional theory study.

The effect of alloying with transition metals (Ni, Co, Fe) on the adsorption strength of phosphoric acid on Pt alloy surfaces was investigated using electrochemical analysis and first-principles calculations. Cyclic voltammograms of carbon-supported PtM/C (M = Ni, Co, and Fe) electrocatalysts in 0.1 M HClO with and without 0.

Highly Durable and Active PtFe Nanocatalyst for Electrochemical Oxygen Reduction Reaction.

Demand on the practical synthetic approach to the high performance electrocatalyst is rapidly increasing for fuel cell commercialization. Here we present a synthesis of highly durable and active intermetallic ordered face-centered tetragonal (fct)-PtFe nanoparticles (NPs) coated with a "dual purpose" N-doped carbon shell. Ordered fct-PtFe NPs with the size of only a few nanometers are obtained by thermal annealing of polydopamine-coated PtFe NPs, and the N-doped carbon shell that is in situ formed from dopamine coating could effectively prevent the coalescence of NPs.

Highly efficient and durable TiN nanofiber electrocatalyst supports.

To date, carbon-based materials including various carbon nanostructured materials have been extensively used as an electrocatalyst support for proton exchange membrane fuel cell (PEMFC) applications due to their practical nature. However, carbon dissolution or corrosion caused by high electrode potential in the presence of O2 and/or water has been identified as one of the main failure modes for the device operation. Here, we report the first TiN nanofiber (TNF)-based nonwoven structured materials to be constructed via electrospinning and subsequent two-step thermal treatment processes as a support for the PEMFC catalyst.

Structure dependent active sites of NixSy as electrocatalysts for hydrogen evolution reaction.

Structure effects of NiS and Ni3S2 nanoparticles were investigated for their electrocatalytic activity in the hydrogen evolution reaction in both acid and alkaline media. Owing to the different atomic configurations and crystalline structures, there is a hydrogen adsorption energy difference, which induces a difference in the activity. From density functional theory calculations and experimental observations, the importance of designing an electrocatalyst with an appropriate atomic configuration is evident.

Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles.

The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface.

P-modified and carbon shell coated Co nanoparticles for efficient alkaline oxygen reduction catalysis.

Described herein is the development of a novel Co-based oxygen electrode catalyst coupled with unique carbon structures. The present carbon shell coated Co nanoparticles of which the surface composites are modified by phosphorus incorporation, exhibit efficient oxygen reduction activities as well as oxygen evolving properties.

Mechanisms of enhanced sulfur tolerance on samarium (Sm)-doped cerium oxide (CeO2) from first principles.

The role of samarium (Sm) 4f states and Sm-perturbed O 2p states in determining the sulfur tolerance of Sm-doped CeO2 was elucidated by using the density functional theory (DFT) + U calculation. We find that the sulfur tolerance of Sm-doped CeO2 is closely related to the modification of O 2p states by the strong interaction between Sm 4f and O 2p states. In particular, the availability of unoccupied O 2p states near the Fermi level is responsible for enhancing the sulfur tolerance of Sm-doped CeO2 compared to the pure CeO2 by increasing the activity of the surface lattice oxygen toward sulfur adsorption, by weakening the interaction between Sm-O, and by increasing the migration tendency of the subsurface oxygen ion toward the surface.

Carbon dioxide conversion into hydrocarbon fuels on defective graphene-supported Cu nanoparticles from first principles.

Density functional theory studies demonstrate that defective graphene-supported Cu nanoparticles can modify the structural and electronic properties of copper for enhancing electrochemical reduction of carbon dioxide (CO2) into hydrocarbon fuels (CH4, CO, and HCOOH). We not only provide improved understanding of CO2 conversion mechanisms on both Cu and the Cu nanoparticle system, but also explain a key factor for enhanced CO2 conversion. A promising catalytic material for CO2 conversion into hydrocarbon fuels may allow for geometry flexibility upon interaction with a key intermediate of CHO*.

Edge-exposed MoS2 nano-assembled structures as efficient electrocatalysts for hydrogen evolution reaction.

Edge-exposed MoS2 nano-assembled structures are designed for high hydrogen evolution reaction activity and long term stability. The number of sulfur edge sites of nano-assembled spheres and sheets is confirmed by Raman spectroscopy and EXAFS analysis. By controlling the MoS2 morphology with the formation of nano-assembled spheres with the assembly of small-size fragments of MoS2, the resulting assembled spheres have high electrocatalytic HER activity and high thermodynamic stability.

Heterogeneous mercury oxidation on au(111) from first principles.

Density functional theory (DFT) studies of mercury oxidation on Au(111) are conducted to determine the potential Hg oxidation mechanisms taking place on catalytic gold surfaces by using the Perdew and Wang approximation (PW91) described by a generalized gradient approximation (GGA). The Hg oxidation was examined via a Langmuir-Hinshelwood mechanism where each Hg(0) and Cl2 (or HCl) species is separately adsorbed on the gold surface and the bimolecular reaction occurs through the formation of bound HgCl and HgCl2. For this, the Climbing Image-Nudged Elastic Band (CI-NEB) method has been employed to calculate the activation energies of HgCl and HgCl2 formation pathways.

Investigation of adsorption behavior of mercury on Au(111) from first principles.

The structural and electronic properties of Hg, SO(2), HgS, and HgO adsorption on Au(111) surfaces have been determined using density functional theory with the generalized gradient approximation. The adsorption strength of Hg on Au(111) increases by a factor of 1.3 (from -9.

A dynamic multimedia environmental and bioaccumulation model for brominated flame retardants in Lake Huron and Lake Erie, USA.

Polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) may pose a worldwide pollution problem because of their persistence, long-range transport capability, and predisposition to bioaccumulate. The ubiquitous presence of PBBs and PBDEs has heightened interest in determination of their fate. We report results for a fugacity-based dynamic environmental and bioaccumulation model of the fate of hexabromobiphenyl (hexaBB) discharged into the Saginaw Bay region of Lake Huron, USA.

Ability of Beijerinckia indica to degrade phenanthrene and reduce hydraulic conductivity.

This study evaluates the ability of Beijerinckia indica (B. indica) as a biomaterial for aerobic biofilm barriers. B.

Stereocontrolled synthesis of oxygen-bridged polycycles via intermolecular [3+2] cyclization of platinum-bound pyrylium with alkenes.

2-(3-Benzyloxy)prop-1-ynyl)benzaldehyde with PtCl(2) in toluene would form Pt-pyryliums that underwent [3+2] cycloaddition with alkenes to the oxygen-bridged (5H-benzo[7]annulen-5-ylidene)platinum(ii) intermediates with good stereoselectivities. Their tandem rearrangement afforded diverse types of polycycles depending on the electronic nature of the alkenes.

Density functional theory studies on the relative reactivity of chloroethenes on zerovalent iron.

The gas-phase dissociation of perchloroethene (PCE), trichloroethene (TCE), and cis-dichloroethene (cis-DCE) on zerovalent iron Fe(110) was investigated using periodic density functional theory (DFT) with the generalized gradient approximation (GGA) and climbing image nudged elastic band method (CI-NEB). Activation energies and dechlorination rate constants for reductive beta-elimination of the chloroethene compounds were calculated using an Arrhenius equation with theoretically calculated vibrational frequencies for the compounds. Activation energies were found to decrease as the chlorination number increases.

Density functional theory studies of chloroethene adsorption on zerovalent iron.

Adsorption of perchloroethene (PCE), trichloroethene (TCE), and cis-dichloroethene (cis-DCE) on zerovalent iron is investigated using density functional theory (DFT) to evaluate hypotheses concerning the relative reactivity of these compounds on zerovalent iron. Four different chloroethene adsorption modes on the Fe(110) surface were studied using periodic DFT and the generalized gradient approximation (GGA). Of the adsorption sites examined, the atop site, where the chloroethene C==C bond straddles a surface iron atom, was the most energetically favorable site for the adsorption of all three chloroethenes.