Adsorption Of Bi Research Articles

Improved Bi(III) absorption and selectivity in cubic TiP2O7 with three-dimensional ion channels

TiP2O7 with enhanced adsorption capacity and selectivity removal ability has emerged as a promising adsorbent for the treatment of heavy metal ions. Herein, layered and cubic TiP2O7@C (LTO and CTO) were prepared by a solvothermal method combined with calcination at 700 and 800 °C, respectively. Compared to the large and non-uniform particles of LTO, the prepared CTO exhibits a honeycomb-like interconnected porous structure composed of uniformly sized ∼25 nm particles and provides a higher concentration of P–OH and Ti–O bonds. Benefiting from the advantages of the physicochemical structure, the adsorption capacity of CTO for Bi(III) was about 1.9 times higher than that of LTO, with a value as high as 54.5 mg g−1. Furthermore, the removal efficiency of Bi(III) from a mixed solution containing eleven ions at a concentration of 10 mg L−1 was as high as 97.5 %, demonstrating its exceptional selective adsorption capacity for Bi(III). The Bi(III) adsorption process is controlled by surface hydroxyl functional groups and follows a quasi-secondary kinetic model. This work may shed light on the synthesis of TiP2O7 and its application in water purification.

In-Situ AFM Studies of Surfactant Adsorption on Stainless Steel Surfaces during Electrochemical Polarization

Corrosion inhibitors are one of the best practices to prevent the far-reaching negative impacts of corrosion on ferrous alloys. A thorough understanding of their corrosion-inhibiting effects is essential for a sustainable economy and environment. Anionic surfactants are known to act efficiently as corrosion inhibitors. Here, we present that in-situ atomic force microscopy (AFM) measurements can provide deep insights into the adsorption and inhibition mechanism of surfactants on stainless steel surfaces during local corrosion. These include the configuration of surfactant molecules on the surface and how the microstructure of the stainless steel surface influences the inhibition process. Three different anionic surfactants, namely palm kernel oil (PKO), linear alkylbenzene sulfonate (LAS), and fatty alcohol ether sulfate (FAES), were investigated on a titanium-stabilized ferritic stainless steel (1.4510) in NaCl solution. For PKO, the results show random adsorption of bi- and multilayer whereas LAS and FAES adsorb only as local corrosion occurs. Thereby, LAS accumulates only locally and especially at the titanium precipitates of the 1.4510 and FAES forms a densely packed monolayer on the surface. This leads to better corrosion inhibiting properties for LAS and FAES compared to PKO.

Adsorption on UiO-66 for preconcentration, matrix separation, slurry sampling and in situ hydride generation-atomic fluorescence spectrometric determination of trace bismuth in alloy and water

The determination of trace bismuth in environmental or alloy samples are rather challenging due to the low abundance and interferences arising from complicated sample matrix including heavy metals. In this work, Zr-based metal organic frameworks (UiO-66) was prepared and utilized to selectively extract Bi(III) from water samples or digests of iron alloy. Following simple centrifugation separation, Bi(III)-adsorbed UiO-66 was re-suspended in dilute hydrochloric acid for direct slurry sampling and in-situ hydride generation for atomic fluorescence spectrometric (HG-AFS) detection of bismuth. Experimental conditions affecting the adsorption of Bi(III) on UiO-66 as well as the slurry sampling HG-AFS process were carefully investigated. Under the experimental conditions, a limit of detection (LOD) of 0.1 ng/mL was achieved for bismuth. Inspiringly, the method could resist interferences from transition metals like Cu(II), Ni(II) and Fe(III), and this ensured reliable analytical results for the determination of trace bismuth in high-purity iron alloy, seawater, and river water samples.

Electrodeposition-Assisted Crystal Growth Regulation of PdBi Clusters on Carbon Cloths for Ethanol Oxidation.

Carbon-supported Pd-based clusters are one of the most promising anodic catalysts for ethanol oxidation reaction (EOR) due to their encouraging activity and practical applications. However, unclear growth mechanism of Pd-based clusters on the carbon-based materials has hindered their extensive applications. Herein, we first introduce multi-void spherical PdBi cluster/carbon cloth (PdBi/CC) composites by an electrodeposition routine. The growth mechanism of PdBi clusters on the CC supports has been systemically investigated by evaluating the selected samples and tuning their compositions, which involve the big difference in standard redox potential between Pd2+/Pd and Bi3+/Bi and easy adsorption of Bi3+ on the surface of Pd-rich seeds. Benefitting from the ensembles of many nanocrystal subunits, multi-void spherical PdBi clusters can present collective properties and novel functionalities. In addition, the outstanding characteristics of CC supports enable PdBi clusters with stable nanostructures. Thanks to the unique structure, Pd20Bi/CC catalysts manifest higher EOR activity and better stability compared to Pd/CC. Systematic characterizations and a series of CO poisoning tests further confirm that the dramatically enhanced EOR activity and stability can be attributed to the incorporation of Bi species and the strong coupling of the structure between PdBi clusters and CC supports.

Role of grain boundary character on Bi segregation-induced embrittlement in ultrahigh-purity copper

Bismuth (Bi), as an impurity element in copper and copper-based alloys, usually has a strong tendency of grain boundary (GB) segregation, which depends on the GB characters. However, the influence of such a segregation on the properties of ultrahigh-purity copper has been rarely reported and the exact structural arrangements of Bi atoms at different GBs remain largely unclear. In this study, we investigated the influence of trace amounts of Bi (50-300 wt ppm) on the ductility of an ultrahigh-purity copper (99.99999%) in the range of room temperature to 900 °C. The tensile results show that the addition of Bi seriously damages the ductility of the ultrahigh-purity copper at temperatures of 450–900 °C, which is due to the GB segregation of Bi. On this basis, such a segregation behavior at different types of GBs, including high and low angle GBs (HAGBs/LAGBs), and twin boundaries (TBs), via the scanning electron microscope-electron backscattered diffraction (SEM-EBSD) and aberration-corrected scanning transmission electron microscope (AC-STEM) investigations, combined with the first-principles calculations were systematically studied. The atomistic characterizations demonstrate an anisotropic Bi segregation, where severe enrichment of Bi atoms typically occurs at the HAGBs, while the absence of Bi adsorption prevails at LAGBs or TBs. In particular, the segregated Bi at random HAGBs exhibited the directional bilayer adsorption, while the special symmetrical Σ7 HAGB presented a unique Bi-rich cluster superstructure. Our findings provide a comprehensive experimental and computational understanding on the atomic-scale segregation of impurities in metallic materials.

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

The mechanism underlying -stimulated bottom-up Au filling and self-passivation in trenches and vias in slightly alkaline electrolytes is explored. The impacts of electrolyte components and and potential-dependent kinetic factors on the rate of Au electrodeposition are quantified experimentally. Derived parameters are applied within the surfactant conservation Curvature Enhanced Accelerator Coverage model to simulate the filling of high aspect ratio trenches. It is observed that Bi adsorption accelerates the Au deposition rate with a non-linear dependence occurring around a critical coverage. Further, the impact of electrolyte composition is such that gradients of and derived from reduction of during deposition accentuate deposition farther from the feature opening. These factors and surface area reduction result in Bi enrichment at the bottoms of filling features that localizes active deposition to feature bottoms. Ultimately, weakening of the concentration gradients and associated kinetics as bottom-up feature filling progresses reduces the Bi coverage on the growth front below the critical value and bottom-up growth terminates. Good agreement is observed with key experimental features including the incubation period of conformal deposition, transition to bottom-up growth, subsequent bottom-up filling and finally self-passivation as the growth front nears the field.

Sn-0.7Cu-10Bi Solder Modification Strategy by Cr Addition

The application of Sn-0.7Cu-based composite solder in electronic packaging is limited due to its high melting point, poor wettability and low mechanical properties. Herein, we propose a strategy of adding Bi and Cr to improve the solderability of Sn-0.7Cu lead-free solder. The results show that the addition of Bi reduces the melting point of the composite solder. Moreover, the Cr particles adsorb at the interface between solder and substrate, thereby reducing the wetting angle of the composite solder. The wetting angle reaches a minimum value of 25.84° when the content of Cr is 0.2 wt.%. The addition of Bi and Cr changes the microstructure of the composite solder. The nucleation rate of β-Sn rises with the increase of Cr content, thus decreasing the size of β-Sn. Furthermore, the addition of Bi and Cr reduces the thickness of the intermetallic compounds (IMCs). This is due to the adsorption of Bi and Cr at the interface of IMCs hinders the atomic diffusion channels and inhibits the growth of IMCs.

First-principles calculation of the resistance to lead-bismuth eutectic corrosion on Fe (111) surface of austenitic stainless steel

The corrosion of liquid metal atoms on the iron surface plays a vital role in the life of the reactor. We use density functional theory (DFT) to study the adsorption energy of Pb and Bi atoms on the Fe (111) surface and the escape energy of Fe atoms on the surface. The adsorption effects of Pb and Bi atom at the fcc site are the best, and the adsorption energies are −2.66 eV and −3.07 eV, respectively. It shows that Bi is more easily adsorbed on the Fe surface than Pb, which is consistent with the experimental phenomena. The escape energies of Fe atoms on clean surface and adsorbed Pb (Bi) surface are 5.11 eV and 4.58 (4.56) eV, respectively, indicating that the adsorption of Pb and Bi on clean Fe (111) surface makes Fe escape more easily. The influence of other alloying elements in steel (Cr, Ni, Ti, Mo, Mn, Si and Al) on corrosion behavior is also studied. The results show that these seven alloying elements all have an inhibitory effect on the adsorption effect of Pb and Bi, thereby weakening the corrosion, but their effects on the escape of Fe are different. Combining the two energies to obtain the total energy (Etot), it shows that both Si and Cr can reduce the dissolution corrosion of steel in LBE.

Oxygen electroreduction on small (

Oxygen reduction reaction (ORR) was studied on {100}-oriented Pt nanoparticles with sizes from 3 to 7 nm in sulphuric acid solution. The distribution and size of nanoparticles was analysed by transmission electron microscopy and metal loading was determined by inductively coupled plasma optical emission spectroscopy. The synthesised nanoparticles have about 40% of Pt(100) facet and 10% Pt(111) as determined from Ge and Bi adsorption, respectively. The four Pt/C catalysts with metal loading from 25 to 38 wt% were tested for ORR activity in 0.5 M H2SO4 solution using the rotating disk electrode method. It was found that the ORR proceeds mainly via a 4-electron pathway with the rate-limiting step being the transfer of the first electron to O2 molecule. The mass activities for ORR increase with decreasing the particle size, but specific activity has a maximum at 4.6 nm particle size. This means the most optimal {100}-oriented Pt size for ORR is around 4.6 nm in sulphuric acid solution.

Rational Design of Catalytic Surfaces for Fuel Cell Technologies by Selective Molecular Patterning

Current green technologies demand for deep and fundamental research. In this sense it has been reported that selective molecular patterning can be employed for the development of highly active electrocatalysts[1,2]. Pt is the most active single-component catalyst for many surface reactions and modifying it with other elements can improve its catalytic performance and stability.Here selective molecular patterning of Pt surfaces with adatoms of Bi and Te at coverages varying from 1/16 ML to 1/4 ML has been studied using DFT to explore changes in the electronic properties of both the adatom and Pt, the sum of which affects catalytic performance of the resulting system.The obtained results indicate that both adatoms are very stable on low-index platinum surfaces at all coverages. The work function of pristine Pt surfaces depends on the exposed plane, and decreases in order (111) > (100) > (110) [4]. In good agreement with experimental data [3] the presence of the adatoms lowers the work function and results in a new trend: (100) > (110) > (111). Further lowering of the model surfaces’ work function with increasing adatoms’ coverage (Table1) also agrees well with the tendencies observed in experimental study of Pt(111) interaction with Bi [3].Table 1. Adatom-Pt(111) WF values. Experimental data for Bi/Pt from ref. [3] is included as well System Coverage Δ WF / eV Experimental value Bi/Pt(111) 0.06 0.73 0.77 0.12 1.26 1.15 0.18 1.65 1.53 0.25 1.96 1.75 Te/Pt(111) 0.06 0.47 — 0.12 0.88 — 0.18 1.22 — 0.24 1.50 — Bi and Te adsorption leads to the charge transfer to the surfaces and the electron density, remaining on the adatoms, gets reorganized to assure the maximal distance from the neighboring Pt atoms, leading to the polarization of the adatom-Pt bond.The adatom-induced changes in the fundamental properties of platinum, such as work function and position of the d-band center, have been observed for both species on all studied surfaces. Even at low 1/16ML coverage Bi and Te not only may block active sites on platinum, but also have a more fundamental impact on its catalytic properties.

Structural and electronic effects of adsorbed Bi on the metallic atomic chains in Au/Si(111)5 [formula omitted] 2

Changes in the structural and electronic properties of the quasi-one-dimensional metal-chain Au/Si(111)5 × 2 reconstruction induced by Bi adsorption were investigated using scanning tunneling microscopy observations, angle-resolved photoelectron spectroscopy measurements and density-functional theory calculations. It was found that Bi atoms substitute the Au atoms in the edge rows of the four-atomic-row Au ridge of the Au/Si(111)5 × 2 reconstruction. The Au/Si(111)5 × 2 surface, which is originally highly heterogenous in its electronic properties, becomes still more heterogeneous upon Bi substitutional adsorption. The overall effect of Bi adsorption resides in the increase of the system Fermi energy due to the electron donation from the Bi atoms to the reconstructed surface. This provides a possibility to tune the metallic properties of the system via controlled Bi dosing.

Study of Surface Stability and Electronic Structure of a Bi-terminated InAs (001) Surface Based on Ab Initio Calculations

In the present work, we have performed a detailed study on the influence of Bi adsorption on the structural and electronic properties of the InAs (001) surface. We have considered five prototypes of Bi/InAs (001)-β2(2 × 4) and α2(2 × 4) structures with different Bi coverage Θ. We have revealed that the substitution of As dimers by Bi atoms introduces structural and geometrical change on the InAs (001) surface. At As-rich conditions, our obtained results prove that the increasing of Bi coverage Θ can stabilize the Bi/InAs (001) structure. The electronic structure of the β2 and α2 are also presented.

Improved Rate for the Oxygen Reduction Reaction in a Sulfuric Acid Electrolyte using a Pt(111) Surface Modified with Melamine.

The feasible commercialization of alkaline, phosphoric acid and polymer electrolyte membrane fuel cells depends on the development of oxygen reduction reaction (ORR) electrocatalysts with improved activity, stability, and selectivity. The rational design of surfaces to ensure these improved ORR catalytic requirements relies on the so-called "descriptors" (e.g., the role of covalent and noncovalent interactions on platinum surface active sites for ORR). Here, we demonstrate that through the molecular adsorption of melamine onto the Pt(111) surface [Pt(111)-Mad], the activity can be improved by a factor of 20 compared to bare Pt(111) for the ORR in a strongly adsorbing sulfuric acid solution. The Mad moieties act as "surface-blocking bodies," selectively hindering the adsorption of (bi)sulfate anions (well-known poisoning spectator of the Pt(111) active sites) while the ORR is unhindered. This modified surface is further demonstrated to exhibit improved chemical stability relative to Pt(111) patterned with cyanide species (CNad), previously shown by our group to have a similar ORR activity increase compared to bare Pt(111) in a sulfuric acid electrolyte, with Pt(111)-Mad retaining a greater than ninefold higher ORR activity relative to bare Pt(111) after extensive potential cycling as compared to a greater than threefold higher activity retained on a CNad-covered Pt(111) surface. We suggest that the higher stability of the Pt(111)-Mad interface stems from melamine's ability to form intermolecular hydrogen bonds, which effectively turns the melamine molecules into larger macromolecular entities with multiple anchoring sites and thus more difficult to remove.

Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory.

Molecular understanding of the electrochemical oxidation of metals and the electro-reduction of metal oxides is of pivotal importance for the rational design of catalyst-based devices where metal(oxide) electrodes play a crucial role. Operando monitoring and reliable identification of reacting species, however, are challenging tasks because they require surface-molecular sensitive and specific experiments under reaction conditions and sophisticated theoretical calculations. The lack of molecular insight under operating conditions is largely due to the limited availability of operando tools and to date still hinders a quick technological advancement of electrocatalytic devices. Here, we present a combination of advanced density functional theory (DFT) calculations considering implicit solvent contributions and time-resolved electrochemical surface-enhanced Raman spectroscopy (EC-SERS) to identify short-lived reaction intermediates during the showcase electro-reduction of Au oxide (AuOx) in sulfuric acid over several tens of seconds. The EC-SER spectra provide evidence for temporary Au-OH formation and for the asynchronous adsorption of (bi)sulfate ions at the surface during the reduction process. Spectral intensity fluctuations indicate an OH/(bi)sulfate turnover period of 4 s. As such, the presented EC-SERS potential jump approach combined with implicit solvent DFT simulations allows us to propose a reaction mechanism and prove that short-lived Au-OH intermediates also play an active role during the AuOx electro-reduction in acidic media, implying their potential relevance also for other electrocatalytic systems operating at low pH, like metal corrosion, the oxidation of CO, HCOOH, and other small organic molecules, and the oxygen evolution reaction.

Intrinsically Fluorescent Biocompatible Terpolymers for Detection and Removal of Bi(III) and Cell Imaging.

Intrinsically fluorescent biocompatible multifunctional multipurpose terpolymers, i.e., methyl methacrylate-co-methyl 3-(N-isopropylacrylamido)-2-methylpropanoate-co-N-isopropylacrylamide (MMA-co-MNIPAMP-co-NIPAm, 1) and methyl methacrylate-co-methyl 3-(N-hydroxymethylacrylamido)-2-methylpropanoate-co-N-hydroxymethylacrylamide (MMA-co-MNHMAMP-co-NHMAm, 2), were synthesized via in situ-attached acrylamido-ester monomers during polymerization of hydrophobic monomers in water medium. These nonconjugated fluorescent terpolymers presenting aggregation-enhanced emissions (AEEs) were suitable for Bi(III) sensors, Bi(III) removal, cell imaging, and security inks. The fluorescence properties, mechanisms of quenching, interactions of Bi(III) with 1 and 2, and Bi(III) adsorption were explored using theoretical analyses of 1, 2, Bi(III)-1, and Bi(III)-2. Considering the overall properties, 1 was more suitable for diverse prospective applications.

Photocatalytic preconcentration of Bi on TiO2 nanoparticles

Titanium dioxide nanoparticles (NP-TiO2) are implemented for the dispersive micro-solid phase extraction of Bi by photocatalytic adsorption by UVA irradiation (365 nm) in the presence of ethanol as a sacrificial agent. The determination of bismuth was carried out by electrothermal atomic absorption spectrometry. The optimization stage was performed using the response surface method, implementing a Box-Behnken design. The proposed methodology does not require pH conditioning of the sample for Bi adsorption on NP-TiO2. The procedure reached limits of detection and quantification of 0.5 and 1.6 ng L−1 respectively. The relative standard deviation was 8.3% for a Bi solution of 50 ng L−1, with a preconcentration factor of 20 when 20 mL of sample were treated with 30 mg of NP-TiO2 and eluted with 1 mL of HNO3. The method was applied to the determination of Bi in digested copper ore samples, obtaining quantitative recoveries.

The electronic, adsorption, and catalytic properties of Bi-, Sb-, and As-nanoclusters

Density functional theory calculations are employed to investigate the electronic, adsorption, and catalytic properties of Bi-, Sb-, and As-nanoclusters. The stability of these clusters are confirmed by the obtained positive binding energies, the change in the free energy, and frequencies, also they can be grown on different substrates such as graphene and hexagonal boron nitride. They have energy gaps ranging from 2.1 to 3 eV that can be controlled by adsorption of different gases or molecules, for instance, adsorption of C2 decreases the gap in Sb-18-a cluster from 2.7 eV to 0.8 eV. These clusters show also interesting adsorption properties where some gases are physically adsorbed (like, N2 and CH4) while others are chemically adsorbed (O2 and SO2). In the first case, the linear N2 molecule has a strong triple bond, from the sp-hybridization, that can’t be broken through the interaction with the clusters, the same occurs also for the sp3-hybridized CH4 with the strong sigma bonds. For the sp2-hybridized O2 molecule, one of the relatively weaker double bond can be broken through the interaction to form another with the cluster. The oxygen evolution reaction (OER) on the edges of these clusters requires lower overpotential than their surfaces due to the moderate adsorption of O by one edge atom with respect to the strong adsorption by two surface atoms. Nanoclusters and quantum dots of Sb provide the best values for the overpotential due to moderate bonding that Sb atoms form with all intermediates not only O, namely overpotentials equal 0.31 and 0.39 V for the nanocluster and the quantum dots, respectively. This significant enhancement of the OER activity makes such clusters strong applicants for water oxidation catalysts.

Pb- and Bi-Modified Pt Electrodes toward Glycerol Electrooxidation in Alkaline Media. Activity, Selectivity, and the Importance of the Pt Atoms Arrangement

Herein we investigated the effect of the adsorption of Bi and Pb on polycrystalline platinum (Ptp) on the electrooxidation of glycerol (EOG) in alkaline media by combining electrochemical, spectros...

Fabricating copper and copper/nickel alloy single crystal bead electrodes with a hydrogen–oxygen torch in ambient air

The use of copper single-crystal electrodes (CSCEs) has revealed the crucial role of electrode structure in electrocatalysis and corrosion. CSCEs, although commercially available, can be prepared in-house by melting the end of a Cu wire to form a single crystal bead (SCB) in ambient air. Unlike the conventional torch used for making Pt and Au SCBs, the torch used in this study allows the Cu bead to cool down to room temperature in a nitrogen stream. The resulting Cu bead is subsequently fabricated into a CSCE with a desired orientation. Copper’s propensity for oxidation does not pose a problem for our method as long as the H2 and O2 fluxes to the flame are well-controlled. The bulk oxide in the Cu SCB prepared as above is below the detection limit of our X-ray photoelectron spectrometer. The devised method opens up an avenue toward the study of electrochemistry at well-defined Cu and possibly other non-noble transition metal electrodes. Moreover, this method can also be used to make alloyed SCBs, as illustrated by the successful fabrication of a Cu/Ni (98.5/1.5) bead. The resulting Cu(1 1 1) and Cu98.5Ni1.5(1 1 1) electrodes are examined by cyclic voltammetry and in situ scanning tunneling microscopy in 0.1 M sulfuric acid. The trace amount of Ni in the Cu(1 1 1) electrode affects the potential, but not the structure, of specific adsorption of the (bi)sulfate anion. A (√3 × √7)–HSO4− structure and the Cu(1 1 1) lattice are imaged by STM at positive and negative potentials.

Removal of Bismuth (III) ions from water solution using a cellulose-based nanocomposite: A detailed study by DFT and experimental insights

Towards determination of trace amount of bismuth (III) ions in real samples, we used cellulose/CBIMMT-resulted-ligand nanocomposite for its preconcentration and separation. The proposed nanocomposite was synthesized by immobilization of a ligand resulted by 4-(4′-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole (CBIMMT) on nanocellulose. The properties of resulted nanocomposite were characterized by TEM, TGA, EDS, elemental analysis CHNS, and BET methods. Moreover, the density functional theory (DFT) was used to deep understanding the changes in the electronic structure of above-mentioned ligand upon Bi(III) adsorption. The most energetically favorable position of adsorption is achieved and the value of adsorption is calculated to be −543.5 kJ/mol that is indication of chemisorption. It is found that the charge distribution of ligand changes significantly upon Bi (III) surface interaction. The operational features such as pH, nanocomposite quantity, extraction time, eluent kind, ionic power and the volume of the sample were optimized for quantifiable determination of bismuth (III) ions. The calibration graph shows a linear range of Bi (III) between 10 and 500 ng mL−1 with the detection limit of 2.68 ng mL−1. The RSD was calculated to be 1.5%. The proposed nanocomposite was utilized as a sensitive sensor of bismuth (III) ions in the real samples.