Adsorption Of Sn Research Articles

Urea Induces Uniform Tin Deposition for Long Cycle‐Life Tin‐based Redox Flow Battery

AbstractAmong multivalent redox flow batteries, the Zn‐based redox flow battery (RFB) has the advantages of high energy density, nontoxicity, and low cost. However, the severe dendrite issue hinders its deployment. Therefore, the Sn‐based RFB is reported as a prospective alternative, particularly in alkaline systems, due to its lower redox potential and four electrons transfer in redox reactions. However, the continuous growth of Sn during charge forms large Sn bulk, which increases the risk of “dead Sn” formation. By combining experiments and theoretical calculations, urea is proposed as an electrolyte additive to regulate Sn deposition on graphite felt. This is achieved through the enhanced adsorption and robust reaction of Sn(OH)62− with graphite felt. Consequently, a more uniform morphology ensues, reducing “dead Sn” formation and thus improving the average discharge voltage and areal capacity. Moreover, the Columbic efficiency becomes more stable, extending the cycle life to over 420 h (>200 cycles) without deep discharge during cycling. This study demonstrates the role of urea in achieving high‐performance Sn‐I flow battery with long cycle life, paving the way for further development of metal‐based hybrid RFBs.

Effectiveness of cork and pine bark powders as biosorbents for potentially toxic elements present in aqueous solution

Cork oak and pine bark, two of the most prolific byproducts of the European forestry sector, were assessed as biosorbents for eliminating potentially toxic elements (PTEs) from water-based solutions. Our research suggests that bioadsorption stands out as a viable and environmental eco-friendly technology, presenting a sustainable method for the extraction of PTEs from polluted water sources. This study aimed to evaluate and compare the efficiency of cork powder and pine bark powder as biosorbents. Specifically, the adsorption of Fe, Cu, Zn, Cd, Ni, Pb and Sn at equilibrium were studied through batch experiments by varying PTEs concentrations, pH, and ionic strength. Results from adsorption-desorption experiments demonstrate the remarkable capacity of both materials to retain the studied PTE. Cork powder and pine bark powder exhibited the maximum retention capacity for Fe and Cd, while they performed poorly for Pb and Sn, respectively. Nevertheless, pine bark showed a slightly lower retention capacity than cork. Increasing the pH resulted in cork showing the highest adsorption for Zn and the lowest for Sn, while for pine bark, Cd was the most adsorbed, and Sn was the least adsorbed, respectively. The highest adsorption of both materials occurred at pH 3.5–5, depending on the PTE tested. The ionic strength also influenced the adsorption of the various PTEs for both materials, with decreased adsorption as ionic strength increased. The findings suggest that both materials could be effective for capturing and eliminating the examined PTEs, albeit with different efficiencies. Remarkably, pine bark demonstrated superior adsorption capabilities, which were observed to vary based on the specific element and the experimental conditions. These findings contribute to elucidating the bio-adsorption potential of these natural materials, specifically their suitability in mitigating PTEs pollution, and favoring the recycling and revalorization of byproducts that might otherwise be considered residue.

Modification of the Ge(0 0 1) subsurface electronic structure after adsorption of Sn

In this work, we investigate how the electronic structure of the Ge(001) surface is modified by the adsorption of Sn atoms. We extend a previously established growth model of the Sn layer formation on Ge(001) with a detailed analysis of surface core-level shifts, observing a prevalence of symmetric Sn ad-dimers at a Sn coverage above onemonolayer. The valence band structure of Ge(001) reveals the appearance of a non-dispersive electronic state after the adsorption of Sn. We correlate the presence of this state to the interaction of electronic states from a Sn ad-dimer configuration with the surface resonances of the Ge up-dimer. Post-deposition annealing leads to full incorporation of Sn and, consequently, to the disappearance of valence band state attributable to Sn ad-atoms. Notably, the adsorption and/or incorporation of Sn removes a Ge(001) surface state above the valence band maximum. The Fermi-level remains pinned close to the valence band maximum, indicating the initial stages of a Schottky barrier formation. Overall, these results provide new fundamental insights into the electronic structure of Sn on Ge(001), crucial for the development of SnGe electronics devices, and more generally of use for understanding the controlled alloying of isoelectronic layered materials.

Controlling the metal work function through atomic-scale surface engineering

Adsorbate induced work function modification of Ni have been investigated by means of first-principles calculations. More specifically, the adsorption of Li, Na, Si, Zr, Pd, Pt, or Sn at various coverages on Ni low-index surface models have been considered. In the case of Sn, a more thorough investigation was performed comparing the adsorption as an overlayer structure with the case of surface alloy formation. Our calculations suggest that the most stable Sn@Ni configuration corresponds to a surface alloy, and here the Ni(100)c(2 × 2)-Sn, Ni(110)c(2 × 2)-Sn, and Ni(111)(3×3)R30∘-Sn surface alloys were found to display similar stability. Concerning the induced work function change, a different behaviour as a function of coverage was observed depending on the nature of the Sn@Ni surface model. Both overlayer adsorption and surface alloying were found to induce a work function decrease already at relatively low coverages (≈ 0.05 atom Å −2), regardless of the underlying surface orientation. However, while the work function obtained for stable surface alloys was found to monotonously decrease as the coverage increases, the work function for the stable overlayer structures goes through a minimum. For all investigated surface modifications, the change in work function was found to be consistent with the orientation of the charge transfer at the adsorbate–surface interface. The computed data in this work may serve as handles for experimental endeavours aiming to optimize properties of active materials through atomic-scale surface engineering.

In-situ STS studies and first principles calculations on bare and Sn adsorbed UHV exfoliated WS2 layers

Abstarct. Two dimensional (2D) derivatives of tin (Sn) have obtained special deliberations recently due to practical realization of planar, as well as, buckled hexagonal lattice of Sn called stanene. However, it has been observed that proper choice of substrate is very important for growth of stanene like films owing to large core size of Sn that prefers sp 3 hybridization over sp 2. Transition metal dichalcogenides (TMDs) like MoS2 or WS2 with honey comb lattice structure seem to be promising substrate candidates for 2D growth of Sn. In the present work, we report mechanical exfoliation of few layers of WS2 under ultra-high vacuum (UHV) conditions and investigations of growth and local electronic structure by in-situ scanning tunneling microscopy (STM) and spectroscopy (STS) studies. Flat WS2 surface with honeycomb lattice structure in the atomic scale with a lattice constant of 0.34 nm is evident in the STM investigations, whereas, STS measurements reveal local density of states (LDOS) of WS2 with a bandgap of approximately 1.34 eV. Density functional theory (DFT) calculations performed by considering bulk WS2 reveal conduction and valence band states comprised of S p and W d at both sides of the Fermi energy (EF) and an indirect bandgap of 1.38 eV. Experimental observations upon Sn adsorption, reveal commensurate growth of Sn atoms on the sulfur `S’ sites with a buckling height of 40 ±10 pm. STS measurements exhibit local electronic structure of the Sn adsorbed surface with clear evidence of in-gap states. DFT calculations quantify the experimental results demonstrating `S’ sites as the most stable sites for the atomic adsorption of Sn with a buckling height of around 80 pm and reveal signature of in-gap hybridized states comprised of Sn p and W d orbitals.

Incorporation of Si and Sn donors in β-Ga2O3 through surface reconstructions

Tin and silicon incorporate on gallium sites in Ga2O3 and act as shallow donors. The monoclinic structure of Ga2O3 has two inequivalent Ga sites; density functional theory calculations for bulk show that Sn prefers the octahedral site, while Si prefers the tetrahedral site. Experiments have indicated that Si and Sn can also incorporate on the thermodynamically less preferred site. We use density functional theory to study the adsorption of Si and Sn and also the co-adsorption of these impurities with Ga and O adatoms on the Ga2O3(010) surface. We identify a number of surface reconstructions in which Si adatoms prefer octahedral sites and Sn adatoms prefer tetrahedral sites. By applying the electron counting rule, we also study the mechanisms of the preferred adsorption sites for Si and Sn. We conclude that Si and Sn can also occupy the thermodynamically unfavored site due to surface reconstructions during the growth, which potentially leads to Si and Sn occupying both octahedral and tetrahedral sites in Ga2O3.

Theoretical study of Sn and Te adsorption over graphene from ab initio calculations

In this work, we report on theoretical calculations for the adsorption of both Sn and Te atoms over a graphene monolayer. Our obtained results show that Sn is chemisorbed over a graphene C–C bond, once the presence of Sn over the substrate changes some of graphene’s C–C sp2-like bond character to a more covalently reactive sp3-like one. On the other hand, Te is physisorbed over a C atom of the graphene sheet, since it is weakly connected to the surface atoms by van der Waals’ forces. However, both Sn and Te are extremely mobile over the graphene monolayer because the energy barriers between the adsorption sites are very small. Considering that SiC surfaces passivated with graphene enhance the strength of the C–Sn bonds in the MBE growth procedure, our results, theoretically, confirm the growth of a SnTe layer on graphene.

Atomic adsorption of Sn on mechanically cleaved WS2 surface at room temperature

Room temperature (RT) adsorption of tin (Sn) under ultra-high vacuum (UHV) conditions on mechanically cleaved tungsten disulfide (WS2) surfaces is reported here. In-situ low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) studies indicate commensurate adsorption of Sn on the hexagonal surface of WS2. Bare WS2 displays an atomic periodicity of lattice constant 0.34 nm. Growth of Sn reveals monomer like a single atom or unpaired (U) and dimer like- or paired (P) adsorptions on the top (`T’) sulfur (S) sites of the trigonal prismatic sublattice within the honeycomb lattice of WS2. The lateral distance between two nearest adsorbed monomers is around 0.34 nm which is exactly similar to the atomic periodicity of the underneath WS2 substrate crystal. For the case of dimer like- adsorption, the separation between two adspecies is 0.293 nm. The bond length of the adsorbed Sn with the surface S atoms is around 40 (±10) pm. We do not find any evidence of Sn adsorption on the bridge (`B’) or hollow (`H’) site of the WS2 lattice. Analysis of the LEED spots and the FFT images of the STM micrographs after Sn adsorption discloses a stretched hexagonal surface which is most likely due to the overall consequence of a perfectly commensurate monomer and nearly commensurate dimer like- adsorptions of the Sn atoms on the WS2 surface.

How the adsorption of Sn on Pt (100) preferentially oriented nanoparticles affects the pathways of glycerol electro-oxidation

In this work we investigate the electro-oxidation of CO and glycerol in acidic media on Pt (100) preferentially oriented nanoparticles unmodified and in presence of Sn adatoms with several coverage degrees. The voltammetric characterization in HClO4 shows that Sn adsorption affects the whole surface, but each domain presents a specific response. Namely, the adsorption of Sn follows the sequence: (100) terraces > (100) short domains > (110) domains. By using CO as surface probe, we demonstrate that the influence of Sn may be both beneficial and detrimental, depending on the nature of the site in which it adsorbs. Specifically, the electro-oxidation of CO on short (110) and (100) domains is anticipated in the presence of Sn, whereas it is hindered on (100) terraces. Concerning the electro-oxidation of glycerol, the influence of Sn is also complex, because Sn adatoms leads to a sensible change in the ways glycerol adsorbs on the surface. Such change anticipates the oxidation steps through a pure bifunctional mechanism that takes place along the surface defects and one-dimensional domains. On the other hand, in bidimensional (100) domains Sn causes a third-body effect that restrains the rupture of CC bonds. Consequently, in situ FTIR analysis shows that the remaining free surface favors the production of species containing carbonyl groups. The global output suggests that the proper combination of well-designed electrocatalysts and adatoms allows the control of the pathways involved in the oxidation of small organic molecules.

Theoretical study of Sn adsorbed on the MgO(100) surface with defects

In this study, the adsorption of Sn atom at various sites on the MgO(100) surface was characterized using a theoretical approach based on density functional theory calculations. Both regular adsorption centers (O 2− and Mg 2+ ) and defects (such as neutral and charged O and Mg vacancies) were considered. Several key parameters for these sites with the adsorbed Sn atom were determined to provide its geometric, energetic, and electronic characterization. The interaction between Sn and the Mg vacancy sites is very strong and is associated with a relatively small distance of the adsorbed Sn atom from the surface and with a large electronic charge transfer from Sn to the surface. A much smaller strength of Sn atom adsorption is observed for the O vacancies and regular sites. Among them, the F s 0 center binds the Sn atom strongest and, in consequence, this atom acquires a significant amount of electronic charge. • The adsorption of Sn at various sites on MgO(100) was characterized theoretically. • Mg vacancies bind Sn very strongly and Sn becomes positively charged. • Regular O 2− sites and O vacancies exhibit much smaller adsorption energies. • Of these sites, the F s 0 center shows the largest magnitude of Sn adsorption energy. • The triplet spin state of Sn is not always preserved upon adsorption.

Nanopowder synthesis of novel Sn(II)-imprinted poly(dimethyl vinylphosphonate) by ultrasound-assisted technique: Adsorption and pre-concentration of Sn(II) from aqueous media and real samples

In this research, a novel Sn(II)-imprinted poly(dimethyl vinylphosphonate) nanopowder (Sn(II)-IPDMVPN) was prepared using Sn2+, dimethyl vinylphosphonate, azobis isobutyronitril and ethylene glycol dimethacrylate as the template, ligand, initiator and cross linker, respectively. The non-imprinted poly(dimethyl vinylphosphonate) nanopowder (NIPDMVPN) was also synthesized utilizing the same procedure without using SnCl2·2H2O in order to compare the results with the Sn(II)-IPDMVPN. The structure, morphology and composition of the products were characterized by XRD, SEM, EDX, XRF, BET, FT-IR and NMR techniques. Some experimental conditions including pH, eluent concentration and sample volume were optimized to maximize Sn(II) adsorption by the Sn(II)-IPDMVPN. It was found that the optimum conditions are pH = 5, 1.00 M of HNO3 as eluent and sample volume up to 50 mL. The results obtained by ICP-MS indicated that the Sn(II)-IPDMVPN had much higher adsorption capacity for Sn(II) ions (about threefold) than the NIPDMVPN. The applicability of the Sn(II)-IPDMVPN was also investigated in three different real samples. Under the best experimental conditions, the calibration graphs were linear in the range of 0.19–90 μg L−1 with a coefficient of determination (R2) of 0.990. The detection limit was calculated to be 0.06 μg L−1. The relative standard deviation (RSD) for six replicate measurements of Sn(II) at 1.00 ng mL−1 was determined to be 1.8%. The results showed that the Sn(II)-IPDMVPN-ICP-MS is a very simple, rapid, sensitive and efficient method for the determination of Sn(II) ions in water samples.

Theoretical study of Sn adsorbed on the Au(1 1 1) surface

In the present work, the adsorption of Sn atoms on the Au(111) surface was theoretically studied in the framework of density functional theory with a slab model. The results show that the most likely site for the adsorption of Sn is the FCC hollow site at low Sn coverage while at full monolayer degeneracy is produced for the four possible adsorption sites. The energy barrier for Sn surface diffusion is of near 0.1eV at low coverage and negligible at high coverage. The magnitude of the Sn adsorption energy, Eads, decreases as the overlayer grows. For high coverage values the Sn-Sn interaction has a predominant contribution to Eads. It was observed that for 1/2ML coverage the adsorbed Sn atoms and the Au atoms of the first and second layers of the substrate can suffer a reordering, resulting in an important surface reconstruction, giving a surface alloy superstructure. An electronic transfer from tin to gold takes place, which is significant at low Sn coverage. The binding of Sn to Au was analyzed in terms of the electronic structure of the Sn/Au(111) system at different values of coverage.

CO electrooxidation on Sn-modified Pt single crystals in acid media

The irreversible adsorption of Sn on the three Pt basal planes (Sn/Pt(111), Sn/Pt(100) and Sn/Pt(110)) and the oxidation of adsorbed carbon monoxide have been studied by cyclic and stripping voltammetry. The presence of Sn adatoms blocks the adsorption of hydrogen on platinum, and leads to the observation of a new oxidation peak ascribed to the four-electron oxidation of the Sn adatom at potentials above 0.5V. The oxidation of adsorbed carbon monoxide is enhanced by the presence of Sn on all three Pt single crystals. On Sn/Pt(111) and Sn/Pt(110), oxidation of adsorbed CO occurs in two distinct potential regions: a pre-peak region at potentials below 0.50V and the main peak at higher potentials. In the pre-peak, the oxidation of adsorbed CO is suggested to take place at the direct interface between Pt and Sn through the formation of an activated water species on Sn that is not observable in the blank voltammetry. In the main peak, the COad oxidation reaction is suggested to occur through the classical bifunctional mechanism of OH adsorbed on Sn with CO adsorbed on Pt atoms no adjacent to Sn atoms. On Sn/Pt(100), the “pre-peak mechanism” is not observed.

Adatom modified shape-controlled platinum nanoparticles towards ethanol oxidation

Different adatom modified shape-controlled Pt nanoparticles have been prepared and their electrocatalytic properties have been evaluated toward ethanol electrooxidation. Based on previous findings with Pt model surfaces, Sn, Rh, Ru and Pb adatoms have been selected as promising surface modifiers. The different adatoms have been gradually incorporated on the surface of the preferentially oriented (100) and (111) Pt nanoparticles under electrochemical conditions. The results obtained in 0.5M H2SO4 indicated that, among the selected adatoms, Sn-modified nanoparticles displayed not only a significant shift to negative values on the onset potential of the ethanol oxidation, but also an important decrease on the hysteresis between the positive and negative sweeps. Interestingly, in chronoamperometic measurements at 0.6V, the oxidation enhancement factors have been found to be dependent on the surface structure of the Pt nanoparticles. On the other hand, Ru and Pb-modified Pt nanoparticles only presented a rather small oxidation enhancement, whereas the activity of the Rh-modified Pt nanoparticles clearly diminished. In alkaline solutions, the oxidation mechanism changes, and the adsorption of Rh, Sn and Pb on the platinum surfaces just displays small catalytic effect at lower coverage for the potential onset in the voltammetric experiments. Ru adsorption does not present any positive effect over the reaction.

Adsorption of Sn(II) on expanded graphite: kinetic and equilibrium isotherm studies

Expanded graphite (EG) was prepared by microwave irradiation at 1000W for 60 s. EG is a novel adsorbent for Sn(II) adsorption and its ability to remove Sn(II) ions from wastewater was investigated. To characterize the adsorptive characteristics of the produced EG, the microstructures of the resultant EG were observed using scanning electron microscopy. Chemical characterization of the surface resultant EG was studied by Fourier transform infrared spectroscopy. The effects of pH, adsorbent dosage, initial concentration, temperature, and contact time on the adsorption surface were studied using the batch process technique. The data fitted with the Langmuir equilibrium isotherm and pseudo-second-order kinetics. The maximum adsorption capacity of Sn(II) on the resultant EG was 378.78 mg g−1.

Adsorption of Sn (II) from Aqueous Solutions on Expanded Graphite

Expanded graphite (EG) was prepared by microwave irradiation at 1000 w for 60 s. It is a novel adsorbent for Sn (Ⅱ) adsorption. This paper aims to investigate the effect of the adsorption of EG. The adsorption behavior of Sn (Ⅱ) from aqueous solution onto EG was investigated with variety of parameters such as pH, adsorbents dosage, initial Sn (Ⅱ) concentration, contact time and temperature. On conditions that the pH was 2.5, the dosage of adsorbent was 0.02 g, the concentration of Sn (Ⅱ) was 200 mg/L and the temperature was 15°C, the maximum removal rate can reach to 98.32%, and the adsorption quantity can reach to 245.7985 mg•g-1. The results showed that the EG was an efficient and novel adsorbent for the removal of stannum from aqueous solution.

Adsorption of Sn on the Ge(111)-(3 × 3) surface studied by ab initio density functional theory

We present detailed ab initio density functional calculations of equilibrium atomic geometry, electronic states, and chemical bonding for the adsorption of the elemental Sn atoms on the Ge(111)-(3 × 3) surface. Three different possible models: (i) IDA model (inequivalent-two-down Sn atoms), (ii) 1U2D model (one-up Sn atom, two-equivalent-down Sn atoms), and (iii) 2U1D model (two-up Sn atoms, one-down Sn atom) have been considered. From these three models, it has been found that the IDA and 1U2D models are energetically favorable than the third model. The energy difference between the IDA and 1U2D model is negligibly small. For the IDA model, the height difference between two down atoms in IDA model is significant. A total of three surface states originating from the Sn adatoms is determined. The results are in good agreement with the recent high-resolution photoemission and scanning tunneling microscopy experiments.

Multilayer Metal Film Plating on Glass

It has been shown that an under-layer of SiO2 · nH2O on a silicate glass surface, promotes the adsorption of Sn(II) hydroxycompounds, resulting in the formation of Sn–O–Si chemical bonds. It also: contributes to the formation of monodispersed Sn(II) compound nanoparticles; levels the glass surface micro-relief; ensures the deposition of fine-grained metal films; increases the rate of Ni–P and Cu electroless plating; and increases the rate of the adhesion interaction between the surface of the silicate glass and metal films. It opens up the possibility of electroless and electrochemical plating of 5–10 μm thick multilayer metal and alloy films.

Theoretical Study of Li, Si, and Sn Adsorption on Single-Walled Boron Nitride Nanotubes

The adsorption of Si, Sn, and Li on single-walled boron nitride nanotubes has been studied by density functional theory calculation. Both single Si or Sn atoms and their dimers are able to adsorb on the outer surface of (8,0) BNNT exothermically. The adsorption of dimers is weaker than that of a single atom. With increasing the tube diameter from (8,0) to (16,0), the adsorption energy of a single atom decreases slightly. The adsorption of single Si and Sn atoms induces magnetism whereas dimers do not. None of the single adatoms or dimers is stable inside the (8,0) BNNT. Except for a single Li atom, all other single adatoms and dimers are stable inside (12,0) BNNT with an adsorption energy of less than −0.4 eV. The alloying of a Li atom with Si or Sn further stabilizes the system, showing that BNNTs encapsulated Si or Sn might be a potential Li storage material.

Characteristics of liquid-liquid immiscibility in Al-Bi-Cu, Al-Bi-Si, and Al-Bi-Sn monotectic alloys: Differential scanning calorimetry, interfacial tension, and density difference measurements

Phase separation in ternary monotectic alloys ${({\mathrm{Al}}_{0.345}{\mathrm{Bi}}_{0.655})}_{90}{X}_{10}$ ($X=\mathrm{Cu},\mathrm{Si},\mathrm{Sn}$; wt %) has been investigated. Experimental work included differential scanning calorimetry and measurements of the liquid-liquid $(l\text{\ensuremath{-}}l)$ interfacial tension and difference in densities of coexisting phases. It is established that the interfacial tension between Al-rich and Bi-rich liquid phases increases when either Cu or Si is added and it decreases when Sn is added to the ${\mathrm{Al}}_{34.5}{\mathrm{Bi}}_{65.5}$ binary. This is related to the size of miscibility gap and is explained by increasing composition gradient across the $(l\text{\ensuremath{-}}l)$ interface upon addition of either Cu or Si and its decreasing upon addition of Sn to the Al-Bi binary. The drop of interfacial tension in liquid ${({\mathrm{Al}}_{0.345}{\mathrm{Bi}}_{0.655})}_{90}{\mathrm{Sn}}_{10}$ against ${\mathrm{Al}}_{34.5}{\mathrm{Bi}}_{65.5}$ is also caused by adsorption of Sn at the interface. Temperature dependences of the interfacial tension and density difference in the alloys studied follow a power law in reduced temperature $({T}_{C}\ensuremath{-}T)$ at approach of the critical point with exponents close to the values predicted by the renormalization group theory of critical behavior.