scholarly journals Metallic surface doping of metal halide perovskites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuze Lin ◽  
Yuchuan Shao ◽  
Jun Dai ◽  
Tao Li ◽  
Ye Liu ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metallic Surface ◽  
Grand Challenge ◽  
New Device ◽  
Surface Doping ◽  
N Doping ◽  
Halide Perovskites ◽  
Heavily Doped ◽  
Low Solubility ◽  
Striking Contrast

AbstractIntentional doping is the core of semiconductor technologies to tune electrical and optical properties of semiconductors for electronic devices, however, it has shown to be a grand challenge for halide perovskites. Here, we show that some metal ions, such as silver, strontium, cerium ions, which exist in the precursors of halide perovskites as impurities, can n-dope the surface of perovskites from being intrinsic to metallic. The low solubility of these ions in halide perovskite crystals excludes the metal impurities to perovskite surfaces, leaving the interior of perovskite crystals intrinsic. Computation shows these metal ions introduce many electronic states close to the conduction band minimum of perovskites and induce n-doping, which is in striking contrast to passivating ions such as potassium and rubidium ion. The discovery of metallic surface doping of perovskites enables new device and material designs that combine the intrinsic interior and heavily doped surface of perovskites.

scholarly journals Micro- and Nanostructured Polyaniline for Instant Identification of Metal Ions in Solution

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 231 ◽  
Author(s):  
Agnieszka Michalska ◽  
Sebastian Golczak ◽  
Krzysztof Langer ◽  
Jerzy Langer
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Current Flow ◽  
Integral Intensity ◽  
Ion Current ◽  
Organic Polymer ◽  
Self Assembled Monolayer ◽  
New Device ◽  
Concentration Of Ions ◽  
Easy Operation

The unique properties of nanomaterials enable the creation new analytical devices. Polyaniline (PANI) micro- and nanofiber network, freestanding in the gap between two gold microelectrodes, has been used in a new nanodetector for metal ions in solutions. The gold electrodes were modified with the aid of alkanethiols, forming a self-assembled monolayer (SAM), which is able to block the ion current flow, but also to interact with metal ions when specific functional molecules are incorporated into the layer. The electric field of the trapped metal ions induces change of the electrical conductivity of polyaniline nanofibers in vicinity. A small injected sample (75 μL) of a solution of salt (about 0.5 μg of salt) was enough to induce a reproducible change in the electrical conductivity of polyaniline nano-network, which was registered as a function of time within 10–20 s. The response was proportional to the concentration of ions. It also depends on properties of ions, e.g., the ionic radius, which allows for identification of metal ions by analyzing the parameters of the signal: the retention time (RT), half width (HW), amplitude (A) and integral intensity (INT). The advantage of the new device is the instant responsiveness and easy operation, but also the simple construction based on organic (polymer) technology. The system is “open”—when learned and calibrated adequately, other metal ions can be analyzed. The nanodetector can be used in cases where monitoring of the presence and concentration of metal ions is important.

The effect of carbon element on optical properties of n-doped Ge on silicon substrate

2018 ◽  
Vol 32 (20) ◽  
pp. 1850224
Author(s):  
Thi Kim Phuong Luong
Keyword(s):  
High Energy ◽  
New Approach ◽  
Transmission Electron ◽  
Active Concentration ◽  
Ge Matrix ◽  
N Doping ◽  
Dopant Atoms ◽  
Low Solubility

Highly n-doped Ge on Si has been demonstrated to be a promising candidate for the compatible light source with silicon technology. In the in-situ n-doping process of Ge epilayers, the active concentration is limited below [Formula: see text] due to low solubility of dopant element in Ge matrix. Many dopant atoms are incorporated in the interstitial sites instead of substitution sites. We present a new approach to increase the electron concentration by adding carbon elements into P-doped Ge epilayers. A gain of PL intensity has been obtained with a factor of 2. The crystalline quality of the Ge film is also investigated owing to using a reflection high-energy electron diffraction (RHEED) apparatus and high-resolution transmission electron microscopy (HR-TEM). Phosphorus dopant is incorporated into Ge epilayers from specific GaP solid source.

scholarly journals Environmental photocatalytic processes with POM. The photodecomposition of atrazine and photoreduction of metal ions from aqueous solutions

2002 ◽  
Vol 4 (1) ◽  
pp. 35-40 ◽  
Author(s):  
A. Hiskia ◽  
A. Troupis ◽  
E. Papaconstantinou
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Cyanuric Acid ◽  
Organic Substrate ◽  
Oh Radical ◽  
Waste Waters ◽  
Inorganic Pollutants ◽  
Radical Attack ◽  
Low Solubility ◽  
Photocatalytic Processes

Polyoxometalate anions (POM), resulting from the condensation of tungstate anions in strongly acidified solutions, can absorb efficiently light in the UV-near Vis region.The produced excited state is a very powerful oxidative reagent which can, mainly via OH radical attack, oxidize and mineralize a great variety of organic pollutants in aqueous solutions, while the photocatalytic circle is closed by reoxidation of the reduced POM, mainly, byO2. Metal ions can also serve as oxidants and close the photocatalytic cycle. In the process metal ions are reduced, precipitated and removed from the solution. Thus photocatalytic treatment for decontamination of waste waters from both organic and inorganic pollutants (metal ions) can be, in principle, achieved.POM+S→hνPOMred+SoxPOMred+Mn+→POM+MredAtrazine, a widely used herbicide with s-triazine structure, is photodecomposed to cyanuric acid in presence ofSiW12O404-in aqueous solutions. However, no precipitation of metal ions is obtained when atrazine is the sole organic substrate in aqueous solutions. The low solubility of atrazine produces insufficient concentration of reduced POM to cause precipitation.

scholarly journals Removal of Heavy Metal Ions from Water and Wastewaters by Sulfur-Containing Precipitation Agents

2020 ◽  
Vol 231 (10) ◽  
Author(s):  
Alina Pohl
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Chemical Precipitation ◽  
Metal Hydroxide ◽  
Central Metal Atom ◽  
Central Metal ◽  
Lower Solubility ◽  
Highly Sensitive ◽  
Tetrahedral Bonding ◽  
Low Solubility

Abstract Restrictive requirements for maximum concentrations of metals introduced into the environment lead to search for effective methods of their removal. Chemical precipitation using hydroxides or sulfides is one of the most commonly used methods for removing metals from water and wastewater. The process is simple and inexpensive. However, during metal hydroxide precipitation, large amounts of solids are formed. As a result, metal hydroxide is getting amphoteric and it can go back into the solution. On the other hand, use of sulfides is characterized by lower solubility compared with that of metal hydroxides, so a higher degree of metal reduction can be achieved in a shorter time. Disadvantages of that process are very low solubility of metal sulfides, highly sensitive process to the dosing of the precipitation agent, and the risks of emission of toxic hydrogen sulfide. All these restrictions forced to search for new and effective precipitants. Potassium/sodium thiocarbonate (STC) and 2,4,6-trimercaptotiazine (TMT) are widely used. Dithiocarbamate (DTC) compounds are also used, e.g., sodium dimethyldithiocarbamate (SDTC), and ligands for permanent metal binding, e.g., 1,3-benzenediamidoethanethiol (BDETH2), 2,6-pyridinediamidoethanethiol (PyDET), a pyridine-based thiol ligand (DTPY) or ligands with open chains containing many sulfur atoms, using of a tetrahedral bonding arrangement around a central metal atom. The possibility of improving the efficiency of metal precipitation is obtained by using a higher dose of precipitating agent. However, toxic byproducts are often produced. It is required that the precipitation agents not only effectively remove metal ions from the solution but also effectively bind with dyes or metal complexes.

Metallic surface doping of SiOx nanowires

2014 ◽  
Vol 11 (5/6/7/8) ◽  
pp. 594 ◽  
Author(s):  
Avi Shalav ◽  
Robert G. Elliman
Keyword(s):  
Metallic Surface ◽  
Surface Doping

scholarly journals Study of the modification mechanism of heavy metal ions adsorbed by biomass-activated carbon doped with a solid nitrogen source

RSC Advances ◽  
2019 ◽  
Vol 9 (64) ◽  
pp. 37440-37449
Author(s):  
Wanlan Zheng ◽  
Shuang Chen ◽  
Huie Liu ◽  
Yudi Ma ◽  
Wenlong Xu
Keyword(s):  
Heavy Metal ◽  
Activated Carbon ◽  
Metal Ions ◽  
Nitrogen Source ◽  
Heavy Metal Ions ◽  
Ultrasonic Method ◽  
Carbon Doped ◽  
Solid Nitrogen ◽  
N Doping ◽  
Redox Method

In this study, the N-doping of biomass-activated carbon with dicyandiamide was performed via an ultrasonic method and a redox method.

Defects in Heavily-Doped MBE GaAs

1982 ◽  
Vol 40 ◽  
pp. 442-445
Author(s):  
C.B. Carter ◽  
D.M. DeSimone ◽  
T. Griem ◽  
C.E.C. Wood
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Heavily Doped

Molecular-beam epitaxy (MBE) is potentially an extremely valuable tool for growing III-V compounds. The value of the technique results partly from the ease with which controlled layers of precisely determined composition can be grown, and partly from the ability that it provides for growing accurately doped layers.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

ELNES of Iron Compounds

1990 ◽  
Vol 48 (2) ◽  
pp. 28-29
Author(s):  
Hiroki Kurata ◽  
Kazuhiro Nagai ◽  
Seiji Isoda ◽  
Takashi Kobayashi
Keyword(s):  
Energy Loss ◽  
Metal Ions ◽  
Energy Resolution ◽  
Transition Metal Oxides ◽  
Local Symmetry ◽  
Iron Compounds ◽  
Fine Structures ◽  
Electron Energy Loss ◽  
Fe Ions ◽  
Electron Energy Loss Spectra

Electron energy loss spectra of transition metal oxides, which show various fine structures in inner shell edges, have been extensively studied. These structures and their positions are related to the oxidation state of metal ions. In this sence an influence of anions coordinated with the metal ions is very interesting. In the present work, we have investigated the energy loss near-edge structures (ELNES) of some iron compounds, i.e. oxides, chlorides, fluorides and potassium cyanides. In these compounds, Fe ions (Fe2+ or Fe3+) are octahedrally surrounded by six ligand anions and this means that the local symmetry around each iron is almost isotropic.EELS spectra were obtained using a JEM-2000FX with a Gatan Model-666 PEELS. The energy resolution was about leV which was mainly due to the energy spread of LaB6 -filament. The threshole energies of each edges were measured using a voltage scan module which was calibrated by setting the Ni L3 peak in NiO to an energy value of 853 eV.

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