On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

Meléndez, Ángel M.; Arroyo, R.; González, Ignacio

doi:10.1002/cphc.201000187

Cited by 25 publications

(22 citation statements)

References 32 publications

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“…However, the reactivity of S n 2− and S 0 species on pyrite and other MS has been rarely investigated (Mikhlin et al 1998;Thomas et al 1998;Schaufuss et al 1998;Nava et al 2008;Meléndez et al 2010). Hence, the most active status of the eMPE surfaces was associated with the content, type and availability of S 0 species, as seen for pyrite and other MS studies (Nava et al 2008).…”

Section: Electrochemical Oxidation Of Unmodified Pyrite Surfacesmentioning

confidence: 95%

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Lara

García‐Meza

Cruz

et al. 2011

Appl Microbiol Biotechnol

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Massive pyrite (FeS₂) electrodes were potentiostatically modified by means of variable oxidation pulse to induce formation of diverse surface sulfur species (S(n)²⁻, S⁰). The evolution of reactivity of the resulting surfaces considers transition from passive (e.g., Fe(1-x )S₂) to active sulfur species (e.g., Fe(1-x )S(2-y ), S⁰). Selected modified pyrite surfaces were incubated with cells of sulfur-oxidizing Acidithiobacillus thiooxidans for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the attached cells density and their exopolysaccharides were analyzed by confocal laser scanning microscopy (CLMS) and atomic force microscopy (AFM) on bio-oxidized surfaces; additionally, S(n)²⁻/S⁰ speciation was carried out on bio-oxidized and abiotic pyrite surfaces using Raman spectroscopy. Our results indicate an important correlation between the evolution of S(n)²⁻/S⁰ surface species ratio and biofilm formation. Hence, pyrite surfaces with mainly passive-sulfur species were less colonized by A. thiooxidans as compared to surfaces with active sulfur species. These results provide knowledge that may contribute to establishing interfacial conditions that enhance or delay metal sulfide (MS) dissolution, as a function of the biofilm formed by sulfur-oxidizing bacteria.

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Section: Electrochemical Oxidation Of Unmodified Pyrite Surfacesmentioning

confidence: 95%

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Lara

García‐Meza

Cruz

et al. 2011

Appl Microbiol Biotechnol

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“…22,23 The Ag 3 SbS 3 phase is a p-type semiconductor with a bulk E g in the range of 1.8-2.0 eV. 24,25 It has wide applications in nonlinear optics and photocatalysts. 24,26 To our best knowledge, there has been no reports on the application of Ag 3 SbS 3 as a solar absorber material (preliminary photoelectrochemical study of Ag 3 SbS 3 has been explored, but no photovoltaic data were reported 27 ).…”

mentioning

confidence: 99%

Ag₃SbS₃Liquid-Junction Semiconductor-Sensitized Solar Cells

Chou

Suriyawong

Aragaw

et al. 2016

J. Electrochem. Soc.

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We present a new ternary semiconductor absorber material -Ag 3 SbS 3 -for solar cells. Ag 3 SbS 3 nanoparticles were grown on mesoporous TiO 2 electrodes using a two-stage successive ionic layer adsorption reaction process. Post annealing transformed the double-layered structure into the Ag 3 SbS 3 phase. The energy gap of the synthesized Ag 3 SbS 3 nanoparticles is estimated to be ∼1.5-1.7 eV. Liquid-junction semiconductor-sensitized solar cells were fabricated from the synthesized nanoparticles using a polysulfide electrolyte. The best cell yielded a short-circuit current density J sc of 11.47 mA/cm 2 , an open-circuit voltage V oc of 0.33 V, a fill factor FF of 38.92%, and a power conversion efficiency η of 1.47% under 1 sun. The external quantum efficiency (EQE) spectrum covered the spectral range of 300-850 nm with a maximal EQE = 80% at λ = 500 nm. At the reduced light intensity of 13% sun, the η increased to 2.18% with J sc = 2.46 mA/cm 2 (which could be normalized to 18.9 mA/cm 2 ). The respectable photovoltaic performance indicates that Ag 3 SbS 3 could be a potential solar absorber material. Semiconductor-sensitized solar cells (SSSCs) have drawn a great deal of attention due to their potential application as a low-cost alternative to Si-based photovoltaic sources. The key component of an SSSC is a mesoporous oxide nanoparticles (usually TiO 2 ) coated with a layer of nanostructured light-absorbing semiconductor. An electrolyte is filled into the porous space of the TiO 2 electrode to complete the charge redox process. Depending on the electrolyte, SSSCs can be classified into two types: solid-state SSSCs (also referred to as extremely thin absorber solar cell-ETA) or liquid-junction SSSCs. The most widely used semiconductor absorber materials are the binary metal chalcolgenides such as CdS, CdSe, PbS, Ag 2 S, Sb 2 S 3 , etc.1-5 These nanostructured semiconductor sensitizers have several advantages including (1) tunable absorption range due to the quantumsize effect, 6 (2) large optical absorption coefficient, 7 and (3) multiple electron-hole pairs produced by a single photon. 8 The highest efficiencies achieved for single-layered binary metal chalcogenide sensitizers are ∼5-7%.9-12 Slightly better efficiencies can be obtained for double-layered core-shell binary sensitizers. [13][14][15] In contrast to binary sensitizers, ternary semiconductors are a relatively unexplored subject. Ternary semiconductors are more difficult to synthesize because there are three elements involved and the stoichiometry must be correct. There are several advantages for ternary semiconductor sensitizers: (1) the energy gap E g can be tuned by varying the ratio among the three elements, (2) large optical absorption coefficients near 10 4 -10 5 cm −1 , and (3) many ternary semiconductors have E g near the optimal E g ∼ 1.4 eV for an optimal solar absorber. 16 However, only a small number of ternary semiconductors, such as CuSbS 2 , Pb-Sb-S, AgInS 2 , AgBiS 2 etc., have been employed as solar absorbers in SSSCs to date (the wi...

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“…Synthesis.-We synthesized Ag 3 SbS 3 with a modified procedure from Gonzalez et al, 10 as described before. 16 Typically, stoichiometric amounts of elemental silver (298.8 mg) and antimony (112.4 mg) were weighed and mixed thoroughly under argon.…”

Section: Methodsmentioning

confidence: 99%

“…A film prepared on a glass slide was used to obtain the diffuse spectra of the material with a cutoff consistent with the bandgap, E g = 2.0 eV previously reported. 10 An optical micrograph is given in supplementary material ( Figure S1). Figure 2 shows the SEM of the material synthesized after grinding; the images at different magnifications are consistent with an amorphous material.…”

Section: Methodsmentioning

confidence: 99%

“…14 Pyrargyrite synthesized by a solid state route and its solid solutions of intermediate compositions covering Ag 2 S, Sb 2 S 3 and Ag 3 SbS 3 were studied electrochemically in aqueous cyanide solutions in the context of Ag extraction from Ag 3 SbS 3 and Ag 3 AsS 3 . 10 In acid media, we are aware of two preliminary reports of pyrargyrite: one for mined powder in 25 mM sulfuric acid 15 that does not include photoelectrochemistry, and our own report of synthesized material in 0.1 M acetic acid. 16 In this paper, we present the solid synthesis of phase-pure pyrargyrite and its photoelectrochemical properties in acid media along with the complimentary material characterization by electron microscopy and X-ray photoelectron spectroscopy.…”

mentioning

confidence: 99%

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Photoelectrochemical Study of Pyrargyrite in Acid Media

Parajuli

Chhetri

Barakoti

et al. 2015

J. Electrochem. Soc.

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Silver antimony sulfide (Ag 3 SbS 3 , pyrargyrite) was synthesized by a solid state route from silver, antimony and sulfur powder precursors under an argon atmosphere. The product was characterized by powder X-ray diffraction (XRD) and found to be Ag 3 SbS 3 pyrargyrite alone, with a bandgap (E g ) of 2.0 eV. We analyzed the ground sample by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The bulk composition was found to be consistent with stoichiometric ratios. Surface characterization by X-ray photoelectron spectroscopy (XPS) indicates that the surface is depleted of Ag and S with an excess of Sb. Surface oxygen was found to be predominantly bound to Sb. The electrochemical and photoelectrochemical behavior of films on fluorine-doped tin oxide was compared to the behavior of bulk electrodes prepared from pieces of pyrargyrite grown under Ar. The films' photoelectrochemical behavior was consistent with a p-type material with the conduction band aligned to reduce H + in acid media. The photocurrent showed evidence of states with energies in the forbidden region that were localized at the surface and filled in the dark. Under illumination, photogenerated holes oxidized these surface states and caused recombination. On platinized films, electrons from H 2 oxidation filled these states. Materials with photocatalytic activity in the visible region of solar spectra are of fundamental and practical interest. In applications for solar energy conversion such as water splitting, there is a need for stable materials that can perform electrochemical reactions.1 Since the first report on water splitting with TiO 2 , 2 the development of materials with lower bandgap, E g , than the ca. 3 eV of TiO 2 (e.g., for anatase E g = 3.2 eV) 3,4 has remained a challenge. Although significant progress has been made (e.g., Refs. 5-7) this remains a challenge because as well as E g , the valence band (VB) and conduction band (CB) must be aligned to enable the reaction of interest while the material must be stable. 8 In this paper, we present the preparation of phase-pure pyrargyrite, a material reported 9-11 to be p-type with E g = 2.0 eV. We propose that this material is of interest for water splitting because the conduction band is aligned for H + reduction to H 2 . Pyrargyrite is a naturally occurring silver ore. Its crystal structure has been studied from mined samples;12 natural crystals present high conductivity due to Ag ion mobility 13 with relatively low activation energy (ca. 0.5 eV). 12,13 This is one example of simple Ag-containing sulfosalts 12 that have received increasing attention because of their ionic conductive properties. 14 Pyrargyrite synthesized by a solid state route and its solid solutions of intermediate compositions covering Ag 2 S, Sb 2 S 3 and Ag 3 SbS 3 were studied electrochemically in aqueous cyanide solutions in the context of Ag extraction from Ag 3 SbS 3 and Ag 3 AsS 3 . 10In acid media, we are aware of two preliminary reports of pyrargyrite: one for mined powder in 2...

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On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

Cited by 25 publications

References 32 publications

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Ag₃SbS₃Liquid-Junction Semiconductor-Sensitized Solar Cells

Photoelectrochemical Study of Pyrargyrite in Acid Media

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On the Reactivity of Sulfosalts in Cyanide Aqueous Media: Structural, Bonding and Electronic Aspects

Cited by 25 publications

References 32 publications

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Ag3SbS3Liquid-Junction Semiconductor-Sensitized Solar Cells

Photoelectrochemical Study of Pyrargyrite in Acid Media

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Product

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Ag₃SbS₃Liquid-Junction Semiconductor-Sensitized Solar Cells