Pb-S Bond Research Articles

Consequences of the Pb-S Bond Formation for Lead Halide Perovskites.

Lead halide perovskites are structurally not stable due to their ionic bonds. Using sulfur agents in the crystal growth improves the stability and performance of the photovoltaic and light-emitting devices. In this theoretical work, we use a small toy S-radical in place of A cation in the bulk of lead iodide perovskite, and highlight the significance of the Pb-S covalent-double-bond formation for: the charge redistribution on the neighboring bonds that also turn to be covalent, phase transformation to a stable non-perovskite structure, and superior optoelectronic properties. The chemical analysis was performed with the Quantum Theory of Atoms In Molecules (QTAIM) and Non-Covalent Interactions (NCI) index. Excitonic properties were obtained from the solution of ab initio Bethe-Salpeter equation. Presence of the spin-orbit coupling triggers an interplay between the Frenkel and charge-transfer multiexcitons, switching between the photovoltaic and laser applications. Multiexcitons obey the exciton-fission preconditions.

Density Functional Theory Study on Structure and Properties of Sulfurized Cerussite (110) Surface

Cerussite is an essential lead oxide mineral with increasing economic importance as lead sulfide resources deplete. This study utilizes density functional theory (DFT) to investigate the structural and electronic properties of the sulfurized cerussite (110) surface. The results show that when the cerussite crystal cleaves along the (110) plane, only the surface layer atoms undergo relaxation to reconstruct the surface, while the atoms located deeper have almost no impact on the reconstructed surface structure. The Pb atoms on the cerussite (110) surface react with the sulfurizing agent to form a PbS deposition layer with a structure similar to galena. This PbS deposition layer is tightly adsorbed onto the lead oxide layer through Pb-S bonds formed by S and subsurface lead oxide structure Pb atoms. The chemical reactivity of Pb atoms in the PbS layer on the sulfurized cerussite (110) surface is more potent than that of Pb atoms on the galena surface; additionally, the Pb atoms closer to the lead oxide layer exhibit slightly higher chemical reactivity than those farther away. This study provides insight into sulfurized cerussite surfaces’ structure and properties at an atomic level and assists in explaining the floating behavior of cerussite.

Efficient Large-Area Quantum Cutting Photoconversion Films for Silicon Solar Cells on Photovoltaic Glass Using Knife Coating.

Yb3+ doped perovskite nanocrystals (PNCs) serve as efficient photoconverters, exhibiting quantum cutting emission at ∼980 nm, which aligns precisely with the optimal response region of silicon solar cells (SSCs). However, severe nonradiative recombination caused by defects in the crystal lattice and film boundaries, along with limitations in small-scale film preparation, restricts their commercial application. Here, we used Ru3+ to mitigate lattice defects in CsPbCl3 PNCs and adjusted the quantum cutting luminescence, achieving a 175% photoluminescence quantum yield (PLQY). The results show that Ru3+ ions enter the perovskite lattice, fill lead vacancies, and passivate the lattice defects. Furthermore, cysteine effectively eliminates surface defects in PNCs by forming Pb-S bonds, resulting in films with a remarkable 117% PLQY, demonstrating strong photoconversion capabilities. Uniformly knife-coated on 20 × 20 cm2 photovoltaic glass, these films increased SSC efficiency from 21.45% to 23.15%. This study showcases a cost-effective photoconverter and a scalable coating method to boost the photovoltaic efficiency of large-area SSCs.

Improved Air Stability for High-Performance FACsPbI3 Perovskite Solar Cells via Bonding Engineering.

Despite the fact that perovskite solar cells (PSCs) are widely popular due to their superb power conversion efficiency (PCE), their further applications are still restricted by low stability and high-density defects. Especially, the weak binding and ion-electron properties of perovskite crystals make them susceptible to moisture attack under environmental stress. Herein, we report an overall sulfidation strategy via introduction of 1-pentanethiol (PT) into the perovskite film to inhibit bulk defects and stabilize Pb ions. It has been confirmed that the thiol groups in PT can stabilize uncoordinated Pb ions and passivate iodine vacancy defects by forming strong Pb-S bonds, thus reducing nonradiative recombination. Moreover, the favorable passivation process also optimizes the energy-level arrangement, induces better perovskite crystallization, and enhances the charge extraction in the full solar cells. Consequently, the PT-modified inverted device delivers a champion PCE of 22.46%, which is superior to that of the control device (20.21%). More importantly, the PT-modified device retains 91.5% of its initial PCE after storage in air for 1600 h and over 85% of its initial PCE after heating at 85 °C for 800 h. This work provides a new perspective to simultaneously improve the performance and stability of PSCs to satisfy their commercial applications.

Probing lead acetate in solution using X-ray diffraction

For the purpose of water purification involving toxic metal sensing and removal, high energy X-ray diffraction experiments have been performed on lead acetate Pb(Ac)2 solutions, liquid and amorphous glutathione disulfide (GSSG), and their mixtures. The data have been interpreted using Empirical Potential Structure Refinement and pair distribution function analysis. At the highest concentration of 1 M Pb(Ac)2 in water, the lead molecules are found to cluster and the second shell in the water structure becomes slightly more ordered as the water molecules become compressed. Liquid and amorphous GSSG are found to hydrogen bond primarily via OH-O interactions, while NH-O bonds are much more distorted. Aqueous solutions of Pb(Ac)2 + GSSG show the closest Pb-O (carboxyl) and Pb-N (amine) bonds both at a distance of 2.5 ± 0.1 Å at a concentration of 1 M Pb(Ac)2 in water. At 0.75 M Pb(Ac)2 in water, strong Pb-S bonds are found at a distance of 2.8 ± 0.1 Å. The implications for lead removal using capacitive deionization are discussed.

Interface Modification for Efficient and Stable Inverted Inorganic Perovskite Solar Cells.

Due to their excellent thermal stability and ideal bandgap, metal halide inorganic perovskite based solar cells (PSCs) with inverted structure are considered as an excellent choice for perovskite/silicon tandem solar cells. However, the power conversion efficiency (PCE) of inverted inorganic PSCs still lags far behind that of conventional n-i-p PSCs due to interfacial energy level mismatch and high nonradiative charge recombination. Herein, the performance of inverted PSCs was significantly improved by interfacial engineering of CsPbI3-x Brx films with 2-mercapto-1-methylimidazole (MMI). It is found that the mercapto group can preferably react with the undercoordinated Pb2+ from perovskite by forming Pb-S bonds, which appreciably reduces the surface trap density. Moreover, MMI modification results in a better energy level alignment with the electron transporting material, promoting carrier transfer and reducing voltage deficit. The above combination results in an open circuit voltage enhancement by 120mV, yielding a champion PCE of 20.6% for 0.09 cm2 area and 17.3% for 1 cm2 area. Furthermore, the ambient, operational and heat stabilities of inorganic PSCs with MMI modification are also greatly improved. Our work demonstrates a simple but effective approach for fabricating highly efficient and stable inverted inorganic PSCs. This article is protected by copyright. All rights reserved.

Maldistribution of Chemical Bond Strength Inducing Exceptional Anisotropy of Thermal Conductivity in Non-Layered Materials.

Currently, the efforts to find materials with high κ anisotropy ratios mainly focus on layered materials, however, the limited quantity and lower workability comparing to non-layered ones boost the exploration of non-layered materials with high κ anisotropy ratios. Here, taking PbSnS3 , a typical non-layered orthorhombic compound, as an example, we propose that maldistribution of chemical bond strength can lead to large anisotropy of κ in non-layered materials. Our result reveals that the maldistribution of Pb-S bonds lead to obvious collective vibrations of dioctahedron chain units, resulting in an anisotropy ratio up to 7.1 at 200 K and 5.5 at 300 K, respectively, which is one of the highest ever reported in non-layered materials and even surpasses many classical layered materials such as Bi2 Te3 and SnSe. Our findings can not only broaden the horizon for exploring high anisotropic κ materials but also provide new opportunities for the application of thermal management.

PH-Dependent PdS3 Site in α3DIV Revealed by Single-Molecule Force Spectroscopy.

Lead is a toxic metal harmful to human beings because of its long history and wide use in human society. The interaction of lead with proteins is one of the most common ways it exerts toxicity. Due to its thiophilic property, lead targets thiol-rich proteins with high affinity and forms stable Pb-S bonds, which may replace the originally bound metal ion and incapacitate the protein/enzyme. Thus, the knowledge of the Pb-S bonds in proteins is important. To study Pb-S bonds, we chose a de novo designed protein α3DIV, able to bind Pb(II) via its three cysteines, as the model protein. Using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS), we proved the formation of a triangular pyramidal PbS3 site in α3DIV by detecting specific Pb-S bond rupture signals, including the previously undetected Pb-S(Cys67) bond. Moreover, the pH-dependent weakening of Pb-S bond strength was revealed and quantified, leading to the dissociation of the PbS3 site at pH 4.5.

The effect of composition changes on the structure and electronic properties of jamesonite: a DFT study.

Models of jamesonite with different compositions were built by different amounts of Sb or Pb substitution at Fe sites, and their structures and electronic properties were studied using the DFT method. The structure and properties of jamesonite significantly changed after Sb or Pb substitution. The lengths of the Sb-S and Pb-S bonds are larger than those of the corresponding Fe-S bonds of pure jamesonite, and the polarization of iron atoms adjacent to substitute atoms is weakened. After one Sb atom substitution, the S atoms bonded to Sb (substitution atom) gain more charges than those before Sb substitution. The Sb atom has more positive charges than the corresponding Fe atom before Sb substitution. For one Pb substitution system, the electrons transfer from the substituted Pb to adjacent S atoms, and the larger negative charge of the S atoms causes a slightly stronger Pb-S bond. With increasing Sb or Pb content, the electronic structural changes of the adjacent atoms are similar to those of one Sb or Pb substitution. However, the increase of 4-coordination Sb or 4-coordination Pb with the decrease of Fe atom changes the electronic structure of jamesonite, which will change its flotation performance.

Constructing heterojunctions by surface sulfidation for efficient inverted perovskite solar cells.

A stable perovskite heterojunction was constructed for inverted solar cells through surface sulfidation of lead (Pb)-rich perovskite films. The formed lead-sulfur (Pb-S) bonds upshifted the Fermi level at the perovskite interface and induced an extra back-surface field for electron extraction. The resulting inverted devices exhibited a power conversion efficiency (PCE) >24% with a high open-circuit voltage of 1.19 volts, corresponding to a low voltage loss of 0.36 volts. The strong Pb-S bonds could stabilize perovskite heterojunctions and strengthen underlying perovskite structures that have a similar crystal lattice. Devices with surface sulfidation retained more than 90% of the initial PCE after aging at 85°C for 2200 hours or operating at the maximum power point under continuous illumination for 1000 hours at 55° ± 5°C.

Synthesis of trimethylacetyl thiobenzamide and its flotation separation performance of galena from sphalerite

A novel surfactant trimethylacetyl thiobenzamide (TTBA) was synthesized and first conducted as flotation separation collector for galena and sphalerite. The flotation performance of TTBA and traditional collector sodium isobutyl xanthate (SIBX) was investigated by micro-flotation, which displayed that TTBA possessed stronger collecting ability than SIBX for galena, as well as better selectivity than SIBX for sphalerite. Zeta potential tests indicated that TTBA possessed superior selectivity to adsorb onto galena surfaces against sphalerite surfaces. FTIR and XPS results showed that TTBA chemisorbed onto galena surfaces with the formation of new chemical bonds. However, before and after treatment by TTBA, there was no obvious change on sphalerite surfaces, indicating no chemisorption occurred. DFT calculations revealed that C = S and C = O groups were the main reaction sites of TTBA, meanwhile, TTBA adsorbed onto galena surfaces by the formation of Pb-S and Pb-O bonds.

Uncovering the hydrophobic mechanism of a novel dithiocarbamate-hydroxamate surfactant towards galena

Flotation separation is determined by chemical additives which can enlarge the hydrophobicity difference of minerals. Herein, S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dipropyl dithiocarbamate (HAPTC) was firstly developed for the flotation separation of galena and sphalerite. In situ AFM imaging elucidated a much stronger adsorption affinity of HAPTC towards galena (PbS) than that to sphalerite (ZnS) at pH 6.2 and 9.0. The AFM force findings and the extended DLVO theory analyses indicated that HAPTC adsorption promoted the hydrophobicity of galena surface more significantly than that of sphalerite. The micro-flotation results showed that HAPTC achieved a selective flotation separation of galena against sphalerite at pH around 9.0. FTIR and XPS uncovered that both dithiocarbamate and hydroxamate groups in HAPTC participated in the bonding interaction with Pb sites on galena surface with the formation of Pb-S and Pb-O bonds. The results provide implications on developing novel reagents, and the fundamental understanding of their adsorption and hydrophobization to minerals at nanoscale.

The selective flotation separation of galena from sphalerite with a novel collector of 5-amyl-1, 2, 4-triazole-3-thione

In this paper, 5-amyl-1,2,4-triazole-3-thione (ATT) was firstly applied as a collector in flotation separation of galena (PbS) from sphalerite (ZnS). Micro-flotation results demonstrated that ATT selectively floated out galena from its mixture with sphalerite at pH ≤10.5. FTIR (Fourier transform infrared), adsorption capacity and contact angle indicated that to increase the pulp pH from ~6.2 to 10.0 dramatically reduced the adsorption of ATT on sphalerite, while had an insignificant effect on its adsorption towards galena. In situ AFM (atomic force microscopy) recommended a monolayer adsorption of ATT on galena surfaces at pH ~6.2 and 10.0. FTIR and XPS (X-ray photoelectron spectroscopy) gave out unequivocal evidences that ATT chemisorbed onto galena through combining surface Pb(II) with ATT's exo-S to generate PbS bond, which orientated ATT's amyl group outward for attaching bubbles, thus to realize the hydrophobization flotation of galena particles.

Two-dimensional Bi2OS2 doping improves the performance and stability of perovskite solar cells

• 2D Bi 2 OS 2 nanosheets are introduced as additives into the perovskite active layer. • Addition of 0.02 mg/ml 2D Bi 2 OS 2 increases power conversion efficiency (PCE) of perovskite solar cells (PVSCs). • The lifetime of optimized PVSCs is also prolonged due to addition of 2D Bi 2 OS 2 . • 2D Bi 2 OS 2 assist the formation of highly crystalline of perovskite thin film. • 2D Bi 2 OS 2 nanosheets can suppress the uncoordinated Pb 2+ ions trap states through Pb-S bond. Additive engineering has been proved to be an effective method to increase the performance of perovskite solar cells (PVSCs) by increasing the quality of the perovskite thin film. Two-dimensional (2D) Bi 2 OS 2 nanomaterial is an excellence optoelectronic material because of its tunable direct band gap, ultra-high charge mobility, wide absorption range and high absorption coefficient. In this work, 2D Bi 2 OS 2 nanosheets are synthesized and introduced as additives into the perovskite precursor solution to adjust the film formation process for the first time. Serving as heterogeneous nucleation site, 2D Bi 2 OS 2 can reduce the nucleation barrier and assist the formation of highly crystalline and crystal orientation along the (1 1 0) plane perovskite thin film, which is beneficial to improve the mobility and lifetime of charge carriers. Besides, X-ray photoelectron spectroscopy (XPS) measurement reveals that 2D Bi 2 OS 2 nanosheets can interact with Pb 2+ within the perovskite through Pb-S bond, thus suppressing the uncoordinated Pb 2+ ions trap states. Scanning electron microscope (SEM) demonstrates 2D Bi 2 OS 2 nanosheets can fill up the pin-holes and grain boundaries on the perovskite film surface. Ultraviolet photoelectron spectroscopy (UPS) measurement indicates that the valence band (VB) of optimized perovskite film is 0.28 eV upshifted closer to the highest occupied molecular orbital (HOMO) of the hole transport layer (HTL), which accelerates the charge transportation at perovskite/HTL interface. Consequently, the average power conversion efficiency (PCE) of 18.96% (highest PCE of 19.89%) is achieved upon incorporating 2D Bi 2 OS 2 nanosheets with an optimized concentration of 0.02 mg/ml into MAPbI 3 precursor solution, which is greatly improved compared to the average PCE of 15.71% for the control devices (highest PCE of 16.77%). Besides, the lifetime of optimized PVSCs is also prolonged due to the less defect states and better perovskite film quality. This work not only provides a facile method to increase the PCE and stability of PVSCs, but also reveals 2D Bi 2 OS 2 material has potential applications in PVSCs.

Revelation of the Nature of the Ligand–PbS Bond and Its Implication on Chemical Functionalization of PbS

Chemical functionalization of metal sulfides by adsorption of specially designed ligands is of primary importance in efficiently manipulating the physicochemical properties of the target surface. D...

Synthesis, flotation performance and adsorption mechanism of 3-(ethylamino)-N-phenyl-3-thioxopropanamide onto galena/sphalerite surfaces

In this paper, a novel β-Oxo thioamide surfactant 3-(ethylamino)-N-phenyl-3-thioxopropanamide (EAPhTXPA) was synthesized and first used as flotation collector for galena and sphalerite. The results of micro-flotation tests showed that EAPhTXPA possessed not only stronger collecting ability but also better selectivity to galena against sphalerite than traditional sulfide collector sodium isobutyl xanthate (SIBX). Adsorption tests indicated that EAPhTXPA could adsorb onto galena surfaces more easily than SIBX, while the adsorption affinity of EAPhTXPA to sphalerite was weaker than that of SIBX. The results of FTIR and XPS spectra demonstrated that there was no chemical bond or new chemical state appeared on sphalerite surfaces after treatment by EAPhTXPA, while Pb-EAPhTXPA complexes were formed on galena surfaces by reaction of EAPhTXPA’s C(S), C(O) and NH groups with surface Pb atoms to build PbS, PbO and PbN bonds. DFT calculations further gave an evidence that the dominated interaction between sphalerite and EAPhTXPA was probably van der Walls forces, and EAPhTXPA reacted with galena by the formation of PbS, PbO and PbN bonds.

Surface Modification of Silica Fume and Adsorption Property of Pb (II) ions

In order to recycle the industrial waste, silica fume of industrial waste was modified with r-mercaptopropyltrimethoxysilane coupling agent (KH590). The adsorption of modified silica fume on lead ions (Pb2+) was studied. The structures were characterized by FTIR and X-ray photoelectron spectroscopy (XPS). FTIR showed that the surface of silica fume was successfully grafted with KH590. XPS showed that the Pb2+ adsorbed on the surface of modified silica fume with coordination Pb-S bond. The effects of reaction time, Pb2+ initial concentration, pH value and adsorbent dosage on the adsorption rate were investigated. The results showed that silica fume modified by KH590 was an efficient lead ion adsorbent and the absorption rate of modified silica fume was up to 96.7%.

Revealing the role of thiocyanate anion in layered hybrid halide perovskite (CH3NH3)2Pb(SCN)2I2.

The effect of the SCN- ion on the structural, electronic, optical, and mechanical properties of the layered (MA)2Pb(SCN)2I2 (MA=CH3NH3+) perovskite is investigated by using first-principles calculations. Our results suggest that the introduction of SCN- ions at the apical positions gives rise to shorter Pb-S bond lengths, more distorted octahedra, and more hydrogen bonds, which have important effects on the electronic, optical, mechanical, and piezoelectric properties in (MA)2Pb(SCN)2I2. Furthermore, a strong relativistic Rashba splitting is induced due to the breaking of the inversion symmetry, which helps to suppress the carrier recombination and enhance the carrier lifetime. The analysis of mechanical properties reveals that the incorporation of SCN- ions is beneficial to strengthen Young's modulus of the perovskite materials and it enhances the piezoelectric properties. Our investigation suggests that doping SCN- ions into the perovskite materials could be a promising strategy to improve the stability and mechanical properties of organic-inorganic hybrid halide perovskite compounds.

The effect of water molecules on the thiol collector interaction on the galena (PbS) and sphalerite (ZnS) surfaces: A DFT study

In froth flotation the molecular interaction between reagents and mineral surfaces take place at the solid liquid interface. In this paper, the effect of water molecule on the three typical thiol collectors (xanthate, dithiocarbomate and dithiophosphate) interactions at the galena (PbS) and sphalerite (ZnS) surfaces has been studied adopting density functional theory (DFT). The results suggests that the presence of water molecule shows a greater influence on the electron distribution of ZnS surface than PbS surface, and reduce the reactivity of ZnS surface atoms but improves the reactivity of PbS surface atoms during the reaction with xanthate. Water adsorption could also reduce the covalent binding between Zn and S atoms but have little influence on Pb-S bond. In the presence of water, xanthate, dithiocarbomate (DTC) and dithiophosphate (DTP) could not adsorb on the sphalerite surface. And for galena (PbS) surface, the interaction of DTP is the strongest, then the DTC and the interaction of xanthate is the weakest. These results agree well with the flotation practice.

Quantifying Geometric Strain at the PbS QD-TiO2 Anode Interface and Its Effect on Electronic Structures

Quantum dots (QDs) show promise as the absorber in nanostructured thin film solar cells, but achieving high device efficiencies requires surface treatments to minimize interfacial recombination. In this work, lead sulfide (PbS) QDs are grown on a mesoporous TiO2 film with a crystalline TiO2 surface, versus one coated with an amorphous TiO2 layer by atomic layer deposition (ALD). These mesoporous TiO2 films sensitized with PbS QDs are characterized by X-ray and electron diffraction, as well as X-ray absorption spectroscopy (XAS) in order to link XAS features with structural distortions in the PbS QDs. The XAS features are further analyzed with quantum simulations to probe the geometric and electronic structure of the PbS QD-TiO2 interface. We show that the anatase TiO2 surface structure induces PbS bond angle distortions, which increases the energy gap of the PbS QDs at the interface.