Patent Application
20190301039
Aspects of the present disclosure involve metal deposits and methods for making the same. In particular, the present disclosure relates to iron deposits and ionic liquid electrolytes used in metal deposition processes.
Conventional metal deposition, such as iron deposition, relies upon caustic aqueous solutions, such as FeSO4/H2SO4 or FeCl2/FeCl3. Large amounts of hydrogen gas evolve at the surface, pitting the substrate and causing the metal deposit to become brittle. The aqueous electrolyte has a narrow stability window of only 1.2 V and a maximum operating temperature between about 80° C. and about 100° C. Conventionally, many metals, such Fe0, cannot be deposited without also decomposing the solvent because of the necessary voltages. Higher temperatures are desired to drive off the hydrogen, but higher temperature lead to unfavorably large crystal grain sizes, which are already a problem because of iron's high intrinsic crystallinity. Moreover, in water, Fe3+ forms at the anode. If low concentrations of Fe3+ migrate to the cathode, then the deposit quality is significantly compromised.
It is with these issues in mind, among others, that aspects of the present disclosure were conceived.
Following the compositions provided herein, a metal deposit on a substrate. The composition consist essentially of a carboxamide, trialkylamine chloride, and a metal salt. The carboxamide may comprise Formula (I):
Also provided herein is a composition for forming an iron deposit on a substrate. The composition consists essentially of a carboxamide, trialkylamine chloride, and a metal salt. The carboxamide may be selected from the group consisting of urea, biuret, triuret, tetrauret, pentauret, hexauret, cyanuric acid, ammelide, ammeline, and combinations thereof. The trialkylamine chloride and the carboxamide may be in molar ratio between 1:1 and 1:30 to form an ionic liquid, wherein the trialkylamine chloride is trimethylamine chloride (TMACl), triethylamine chloride (TEACl), or combinations of the two. The metal salt may have the formula MXy, wherein M is a metal, X is a halide, and y is an oxidation number of M. The metal salt may be in a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid. The iron deposit may have an average grain size between about 0.2 μm and about 3 μm and contains less than about 1 mol % of each oxygen, carbon, and chlorine.
The present disclosure provides a metal deposit formed from any composition described herein. For example, an iron deposit may have an average grain size between about 0.2 μm and about 3 μm and may contain less than about 1 mol % of each oxygen, carbon, and chlorine. This iron deposit may be formed on a substrate by inducing a potential between an iron salt and the substrate through an electrolyte to cause a metal-metal bond to form between the iron salt and metal on the substrate. The electrolyte may comprise trialkylamine halide, urea, and an iron salt. The trialkylamine halide and carboxamide may be in molar ratio between about 1:1 and about 1:30 to form an ionic liquid, such at about 1:1 (mol/mol) or about 1:30 (mol/mol). The iron salt, such as FeCl3, may be at a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid.
Also provided herein a method comprising, inducing a potential between a metal salt and a substrate through an electrolyte to deposit metal onto the substrate by causing a metal-metal bond to form between the metal salt and metal on the substrate. In this method, the potential may have a current density between about 10 mA/cm3 and about 300 mA/cm3 and a reduction potential of between about −0.6 V and about −2.2 V. The electrolyte may comprise trialkylamine chloride, a metal salt, and a carboxamide of Formula (I):
The trialkylamine chloride and carboxamide may be in molar ratio between 1:1 and 1:30 to form an ionic liquid. The trialkylamine chloride may be trimethylamine chloride (TMACl), triethylamine chloride (TEACl), or combinations of the two. The metal salt has the formula MXy, wherein M is a metal, X is a halide, and y is an oxidation number of M. The metal salt may be in a concentration between about 0.2 and about 1.0 moles per liter of the ionic liquid (that is, 0.2-1.0 M). The deposited metal produced from this method may have an average grain size between about 0.2 μm and about 3 μm, such as between about 0.5 μm and about 2 μm, and contains less than about 1 mol % of each oxygen, carbon, and chlorine, as verified through electron microscopy and energy-dispersive spectroscopy.
The present disclosure provides a metal deposit formed by any method described herein. For example, an iron deposit may have an average grain size between about 0.2 μm and about 3 μm and may contain less than about 1 mol % of each oxygen, carbon, and chlorine. This iron deposit may be formed on a substrate by inducing a potential between an iron salt and the substrate through an electrolyte to cause a metal-metal bond to form between the iron salt and metal on the substrate. The electrolyte may comprise trialkylamine halide, carboxamide, and an iron salt. The trialkylamine halide and carboxamide may be in molar ratio between about 1:1 and about 1:30 to form an ionic liquid, such at about 1:2 (mol/mol) or about 1:10 (mol/mol). The iron salt, such as FeCl3, may be at a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid.
Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification, or may be learned by the practice of the embodiments discussed herein. A further understanding of the nature and advantages of certain embodiments may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Example embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.
Provided herein are methods, devices and compositions which deposit highly pure, dense metal deposits onto substrates from an electrolyte. The electrolyte comprises trialkylamine halide, carboxamide, and a metal source, such as an iron salt. In another example, the electrolyte comprises trialkylamine halide and carboxamide in molar ratio between about 1:1 and about 1:30 to form an ionic liquid, such as about 1:2 or about 1:10. The metal source is at a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid (that is, 0.2-1.5 M), such as about 0.3 M. A potential is induced between the metal source and a substrate through the electrolyte. Metal is thereby deposited onto the substrate by causing a metal-metal bond to form between the metal source and metal on the substrate. Included also in this disclosure are metal deposits formed using the methods disclosed herein and compositions employed in the method.
Using the disclosed methods, hydrogen is not evolved at the substrate during metal deposition and denser metal is deposited compared to previously known methods. Voltage and temperature operate in wider windows of the induced potential relative to conventional aqueous electrolytes, and the average grain size of deposited metal is better controlled compared to previous deposits. When iron is present, Fe3+ is reduced completely to Fe0, thus avoiding the catastrophic system failures which plague prior methods and systems. Moreover, as evinced by the microscopic and energy-dispersive spectroscopic data disclosed herein, the metal deposits have surprisingly high purity and conformity. These deposits are corrosion resistant, substantially free from oxygen, carbon, and chlorine, and adhering strongly to the substrates upon which the metal deposit is formed.
The present disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as described above. It is noted that, for purposes of illustrative clarity, certain elements in various drawings may not be drawn to scale, may be represented schematically or conceptually, or otherwise may not correspond exactly to certain physical configurations of embodiments.
The present disclosure provides a method for depositing metal onto a substrate, for example a working electrode (workpiece) of an electrochemical cell. The substrate may be any electrically conductive surface, including metals such as steel or iron, or common electrode materials, such as glassy carbon.
The methods according to this disclosure can be understood with relation to exemplary devices. Referring to
According to the methods of this disclosure, when potential between a metal source and a substrate through an electrolyte, metal is thereby deposited onto the substrate by causing a metal-metal bond to form between the metal source and metal on the substrate. In particular embodiments, a potential may be induced between a metal source and a substrate through an electrolyte to deposit metal onto the substrate by causing a metal-metal bond to form between the metal source and metal on the substrate.
Referring to
The methods disclosed herein induce a potential between a metal source and a substrate through an electrolyte. The potential has features which can be varied to effect the outcome of the method and the characteristics of the deposited metal. These features include current density and a reduction potential.
The potential may have a current density ranging between about 0 mA/cm3 and about 300 mA/cm3. In various embodiments, the current density may be between about 0 mA/cm3 and about 5 mA/cm3, between about 5 mA/cm3 and about 10 mA/cm3, between about 10 mA/cm3 and about 15 mA/cm3, between about 15 mA/cm3 and about 20 mA/cm3, between about 20 mA/cm3 and about 25 mA/cm3, between about 25 mA/cm3 and about 30 mA/cm3, between about 30 mA/cm3 and about 35 mA/cm3, between about 35 mA/cm3 and about 40 mA/cm3, between about 40 mA/cm3 and about 50 mA/cm3, between about 50 mA/cm3 and about 100 mA/cm3, between about 100 mA/cm3 and about 150 mA/cm3, between about 150 mA/cm3 and about 200 mA/cm3, between about 200 mA/cm3 and about 250 mA/cm3, or between about 250 mA/cm3 and about 300 mA/cm3, or any current density therebetween. The current density may be less than about 300 mA/cm3, such as less than about 100 mA/cm3, or less than about 50 mA/cm3. The current density may be more than about 10 mA/cm3, such as more than about 50 mA/cm3, or more than about 100 mA/cm3. In particular, the current density may be about 20 mA/cm3. Alternatively, the current density may be about 40 mA/cm3.
The potential may have a reduction potential ranging of between about −0.6 V and about −2.2 V. A reduction potential of −2.2V is close to the boundary of the electrochemical stability window of the electrolytes disclosed herein, causing the grain structure of the deposited metals to become more varied. Thus, the reduction potential tends to be more positive than about −2.2 V. In various embodiments, the reduction potential may be between about −0.6 V and about −0.7 V, between about −0.7 V and about −0.8 V, between about −0.8 V and about −0.9 V, between about −0.9 V and about −1.0 V, between about −1.0 V and about −1.1 V, between about −1.1 V and about −1.2 V, between about −1.2 V and about −1.3 V, between about −1.3 V and about −1.4 V, between about −1.4 V and about −1.5 V, between about −1.5 V and about −1.6 V, between about −1.6 V and about −1.7 V, between about −1.7 V and about −1.8 V, between about −1.8 V and about −1.9 V, between about −1.9 V and about −2.0 V, between about −2.0 V and about −2.1 V, or between about −2.1 V and about −2.2 V. The reduction potential may be less than about −0.6 V.
The methods described herein use an electrolyte. Generally, the electrolyte comprises an ionic liquid and a metal source, which is a source for new material deposited at the substrate. In particular, the electrolyte may comprise ionic liquid formed from trialkylamine halide and carboxamide. The metal source is mixed with or dissolved in the ionic liquid. The electrolyte may also comprise one or more additives, for example, a silica-providing agent such at tetraethoxysilane (ortho silicate, TEOS).
Generally, the electrolyte comprises an ionic liquid formed from trialkylamine halide and carboxamide in molar ratio between about 1:1 and about 1:30, especially at a molar ratio of about 1:2 or of about 1:10. In another example, the electrolyte may only contain a trace amount of water, such as that absorbed from the atmosphere. That is, the electrolyte may be substantially non-aqueous.
The alkyl groups of the trialkylamine halide may be the same or different. The alkyl groups may be lower alkyl containing from one to eight carbon atoms in the principal chain and up to 20 carbon atoms. The alkyl groups may be straight or branched chain or cyclic and include methyl, ethyl, propyl, isopropyl, butyl, hexyl and the like. The alkyl groups may be optionally substituted with one or more hydroxyl groups, such as a methanol, ethanol, or propanol substituent. As such, the trialkylamine halide may be trimethanolamine halide, triethanolamine halide, or tripropanolamine halide.
The halide in the trialkylamine halide may be fluoride, chloride, bromide, or iodine. For example, the halide may be chloride. In particular, the trialkylamine halide may be a trialkylamine chloride, such as trimethylamine chloride (TMACl), triethylamine chloride (TEACl), or combinations of the two. That is, the trialkylamine halide may be trimethylamine chloride. Alternatively, the trialkylamine halide may be triethylamine chloride.
The carboxamide may comprise Formula (I):
Generally, at least one Q is an O.
The carboxamide of Formula (I) may comprise a compound of Formula (II):
That is, the carboxamide of Formula (II) is a carboxamide of Formula (I), wherein Q is O, and R3 is NR4R5.
The carboxamide of Formula (II) may comprise a compound of Formula (III):
That is, the carboxamide of Formula (III) is a carboxamide of Formula (II), wherein R1, R2, R4, and R5 are each H. Viewed another way, the carboxamide of Formula (III) is a carboxamide of Formula (I), wherein Q is O, R3 is NR4R5, and wherein R1, R2, R4, and R5 are each H. When n is 1, the carboxamide is urea. When n is 2, the carboxamide is biuret. When n is 3, the carboxamide is triuret. When n is 4, the carboxamide is tetrauret. When n is 5, the carboxamide is pentauret. When n is 6, the carboxamide is hexauret.
The carboxamide of Formula (I) may comprise a compound of Formula (IV):
That is, a carboxamide of Formula (IV) is a carboxamide of Formula (I), wherein R1 and R3 have been taken together to form a ring.
The carboxamide of Formula (IV) may comprise a compound of Formula (V):
That is, the carboxamide of Formula (V) is a carboxamide of Formula (IV), where n is 3. Viewed another way, the carboxamide of Formula (V) is a carboxamide of Formula (I), wherein R1 and R3 have been taken together to form a ring, and n is 3; that is, a 6-membered ring.
In some embodiments, the carboxamide of Formula (I) may be selected from the group consisting of urea, biuret, triuret, tetrauret, pentauret, hexauret, cyanuric acid, ammelide, ammeline, and combinations thereof. The carboxamide may be selected from the group consisting of cyanuric acid, ammelide, ammeline, and combinations thereof, encompassing a compound of Formula (V). The carboxamide may be selected from the group consisting of urea, biuret, triuret, tetrauret, pentauret, hexauret, and combinations thereof, encompassing a compound of Formula (III). In particular, the carboxamide may be urea or biuret. In exemplary embodiments, the carboxamide is urea.
Without wishing to be bound by theory, the carboxamide is a proton carrier, which permits the formation of the ionic liquid when combined with the trialkylamine halide in specific molar ratios. Generally, the trialkylamine halide and carboxamide may be in molar ratio between about 1:1 and 1:30. In various embodiments, the trialkylamine halide and carboxamide may be in molar ratio between about 1:1 and about 1:2, between about 1:2 and about 1:3, between about 1:3 and about 1:4, between about 1:4 and about 1:5, between about 1:5 and about 1:6, between about 1:6 and about 1:7, between about 1:7 and about 1:8, between about 1:8 and about 1:9, between about 1:9 and about 1:10, between about 1:10 and about 1:11, between about 1:11 and about 1:12, between about 1:12 and about 1:13, between about 1:13 and about 1:14, between about 1:14 and about 1:15, between about 1:15 and about 1:16, between about 1:16 and about 1:17, between about 1:17 and about 1:18, between about 1:18 and about 1:19, between about 1:19 and about 1:20, between about 1:20 and about 1:21, between about 1:21 and about 1:22, between about 1:22 and about 1:23, between about 1:23 and about 1:24, between about 1:24 and about 1:25, between about 1:25 and about 1:26, between about 1:26 and about 1:27, between about 1:27 and about 1:28, between about 1:28 and about 1:29, or between about 1:29 and about 1:30.
The trialkylamine halide and carboxamide may be in molar ratio of greater than about 1:2, such as greater than about 1:5. The trialkylamine halide and carboxamide may be in molar ratio of less than about 1:30, such as less than about 1:20, or less than about 1:10. In particular, the trialkylamine halide and carboxamide may be in molar ratio of about 1:2. The trialkylamine halide and carboxamide may be also in molar ratio of about 1:5. Alternatively, the trialkylamine halide and carboxamide may be in molar ratio between about 1:10.
In particular, the carboxamide may be urea, wherein the trialkylamine halide and urea may be in molar ratio of greater than about 1:2, such as greater than about 1:5. The trialkylamine halide and urea may be in molar ratio of less than about 1:30, such as less than about 1:20, or less than about 1:10. In particular, the trialkylamine halide and urea may be in molar ratio of about 1:2. The trialkylamine halide and urea may be also in molar ratio of about 1:5. Alternatively, the trialkylamine halide and urea may be in molar ratio between about 1:10.
When the potential is induced, the electrolyte may have at a temperature above 50° C. and below about 300° C., such between about 50° C. and about 60° C., between about 60° C. and about 70° C., between about 70° C. and about 80° C., between about 80° C. and about 90° C., between about 90° C. and about 100° C., between about 100° C. and about 110° C., between about 110° C. and about 120° C., between about 120° C. and about 130° C., between about 130° C. and about 140° C., between about 140° C. and about 150° C., between about 150° C. and about 160° C., between about 160° C. and about 170° C., between about 170° C. and about 180° C., between about 180° C. and about 190° C., between about 190° C. and about 200° C., between about 200° C. and about 210° C., between about 210° C. and about 220° C., between about 220° C. and about 230° C., between about 230° C. and about 240° C., between about 240° C. and about 250° C., between about 250° C. and about 260° C., between about 260° C. and about 270° C., between about 270° C. and about 280° C., between about 280° C. and about 290° C., or between about 290° C. and about 300° C. The temperature may be less than about 300° C., such as less than about 150° C. The temperature may be more than about 0° C., such as more than about 100° C. In particular, the electrolyte may have a temperature between about 80° C. and about 120° C. when the potential is induced, such as at about 100° C.
The pH of the electrolyte may vary depending upon the embodiment. Different metals and composites typically have pH requirements to maintain a stable mixture in solution.
Generally, the electrolyte comprises a metal source. The metal source may be metal particles, such as dissolved or suspended metallic micro- or nanoparticles, or molecular metal ions, such as dissolved metal salts. Referring to
Examples of suitable metals include, but are not limited to, zinc, cadmium, copper, nickel chromium, tin, gold, silver, platinum, lead, ruthenium, rhodium, palladium, osmium, iridium, iron, cobalt, indium, arsenic, antimony, bismuth, manganese, rhenium, aluminum, zirconium, titanium, hafnium, vanadium, niobium, tantalum, tungsten, and molybdenum. Examples of suitable alloys having two metals include, but are not limited to gold-copper-cadmium, zinc-cobalt, zinc-iron, zinc-nickel, brass (an alloy of copper and zinc), bronze (copper-tin), tin-zinc, tin-nickel, and tin-cobalt. Especially suitable metals are molybdenum, tine, iron, and copper. In particular, the metal may be iron.
In some embodiments, the metal source may be provided into the electrolyte by a pressed anode. The pressed anode comprises one or more metals selected from the group consisting of Mo, Sn, Zn, Al, Fe, and Cu. The pressed anode may also be formed from an alloy such as bronze (Cu—Sn). The pressed anode may be produced following the procedure of Example 5 disclosed herein.
Alternatively, or in addition to, the electrolyte may comprise a metal salt. Any metal salt known within the electrochemical arts is suitable for use in this method. In some instances, the metal source may be a metal salt having the formula MXy, wherein M is a metal, X is a halide, and y is an oxidation number of M. In particular, the metal salt MXy may be FeCl3.
M may be any suitable metal, such as those listed above. In particular, M may be Fe. As such, MXy may be FeXy, where X is a halide and y is an oxidation state of Fe. In particular, the metal salt FeXy may be FeCl3.
X may be any halide, such as fluoride, chloride, bromide, or iodide. In particular, X may be Cl. As such, MXy may be MCly. Generally, the halide of the salt is selected to correspond with the halide of the trialkylamine halide. For example, when the trialkylamine halide is a trialkylamine chloride, the metal salt MXy is selected to be MCly, wherein the halide of the metal salt is chloride as well. In particular, the metal salt MCly may be FeCl3.
The number y may be any oxidation number available to the suitable metals, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. y may be 2. y may be 2 or 3. In particular, y may be 3. As such, MXy may be MX3, where M is selected from among suitable metals which can have an oxidation state of 3+. In particular, the metal salt MX3 may be FeCl3.
Generally, the metal source is at a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid; that is, between about 0.2 M and about 1.5 M. In various embodiments, the metal source is at a concentration between about 0.2 M and about 0.25 M, between about 0.25 M and about 0.3 M, between about 0.3 M and about 0.35 M, between about 0.35 M and about 0.4 M, between about 0.4 M and about 0.45 M, between about 0.45 M and about 0.5 M, between about 0.5 M and about 0.55 M, between about 0.55 M and about 0.6 M, between about 0.6 M and about 0.65 M, between about 0.65 M and about 0.7 M, between about 0.7 M and about 0.75 M, between about 0.75 M and about 0.8 M, between about 0.8 M and about 0.85 M, between about 0.85 M and about 0.9 M, between about 0.9 M and about 0.95 M, between about 0.95 M and about 1.0 M, between about 1.0 M and about 1.05 M, between about 1.05 M and about 1.1 M, between about 1.1 M and about 1.15 M, between about 1.15 M and about 1.2 M, between about 1.2 M and about 1.25 M, between about 1.25 M and about 1.3 M, between about 1.3 M and about 1.35 M, between about 1.35 M and about 1.4 M, between about 1.4 M and about 1.45 M, or between about 1.45 M and about 1.5 M. The concentration of metal source may be more than about 0.2 moles per liter of the ionic liquid. The concentration of metal source may be less than about 1.5 moles per liter of the ionic liquid. In particular, the concentration of metal source may be about 0.3 moles per liter of the ionic liquid.
The electrolyte may further comprise one or more additives, including but not limited to, organic solvents, acids, bases, salts, surfactants, thickeners, buffers, ionizable organic compounds, and silica-providing agents. In particular, the electrolyte may comprise thickener to modulate the viscosity and increase the mass of particulates stably suspended in the liquid electrolyte.
The electrolyte compositions may include a silica-providing agent. Examples of silica-providing agents include, but are not limited to, silica, silicon dioxide, silicic oxide, colloidal silica, silica gel, kieselguhr, quartz, tridymite, cristobalite, keatite, moganite, stishovite, seifertite, melanophlogite, sand, and monomeric silanes. The silica-providing agent may be hydrated, precipitated, fumed, fused, fibrous, mesoporous, and/or micronized. The silica provided by the silica-providing agent may be microcrystalline or present on the micrometer or nanometer scale.
When the silica-providing agent is a monomeric silane, the agent can be hydrolyzed, thermally, or electrochemically decomposed to provide microcrystalline silica dispersed throughout the metal deposit. The monomeric silane may be trialkoxysilane, such as triethoxysilane, or a tetraalkoxysilane, such as tetraethoxysilane (e.g. Wacker® TES 28, tetraethyl orthosilicate). Wacker® TES 28 is a monomeric silane, which can be hydrolyzed to form silicon dioxide (silica). Other suitable examples of trialkoxysilanes include trimethoxysilane, tripropoxysilane, and triisopropoxysilane. Other suitable examples of tetraalkoxysilanes include tetramethoxysilane, tetrapropoxysilane, and tetraisopropoxysilane. In particular, the electrolyte comprises tetraethoxysilane.
When present, the organic solvent may be a polar protic solvent, a polar aprotic solvent, a non-polar solvent, or combinations thereof. Suitable examples of polar protic solvents include, but are not limited to alcohols such as methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, s-butanol, t-butanol, and the like; diols such as propylene glycol; organic acids such as formic acid, acetic acid, and so forth; amines such as trimethylamine, or triethylamine, and the like; amides such as formamide, acetamide, and so forth; and combinations of any of the above.
Non-limiting examples of suitable polar aprotic solvents include acetonitrile, dichloromethane (DCM), diethoxymethane, N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylpropionamide, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), 1,3-dimethyl-2-imidazolidinone (DMI), 1,2-dimethoxyethane (DME), dimethoxymethane, bis(2-methoxyethyl)ether, 1,4-dioxane, N-methyl-2-pyrrolidinone (NMP), ethyl formate, formamide, hexamethylphosphoramide, N-methylacetamide, N-methylformamide, methylene chloride, nitrobenzene, nitromethane, propionitrile, sulfolane, tetramethylurea, tetrahydrofuran (THF), 2-methyltetrahydrofuran, trichloromethane, and combinations thereof.
Suitable examples of non-polar solvents include, but are not limited to, alkane and substituted alkane solvents (including cycloalkanes), aromatic hydrocarbons, esters, ethers, combinations thereof, and the like. Specific non-polar solvents that may be employed include, for example, benzene, butyl acetate, t-butyl methylether, chlorobenzene, chloroform, chloromethane, cyclohexane, dichloromethane, dichloroethane, diethyl ether, ethyl acetate, diethylene glycol, fluorobenzene, heptane, hexane, isopropyl acetate, methyltetrahydrofuran, pentyl acetate, n-propyl acetate, tetrahydrofuran, toluene, and combinations thereof.
An electrolyte comprising organic solutions frequently exhibit greater viscosity, which can cause slower molecular diffusion but benefits from increased particle suspension capacity. Electrolyte having organic solvent may also display much larger electrochemical windows (2 V to 6 V), compared to water (about 1.23 V). Organic solvents may also have greater operating temperature ranges above the 100° C. limit for aqueous systems. Generally, organic solutions do not codeposit with the metal during deposition.
The range of concentration of additives in the electrolyte can and will vary. Generally, the concentration of additives in the electrolyte may range between about 10−2 mol/L and about 10−5 mol/L, such as between about 10−2 mol/L and about 10−3 mol/L, between about 10−3 mol/L and about 104 mol/L, or between about 104 mol/L and about 10−5 mol/L.
A metal deposit may be formed by any method described herein. In particular, these metal deposits may be an iron deposit formed from an iron-containing metal source.
Generally, the metal deposit may have an average grain size ranging between about 0.2 μm and about 3 μm. In various embodiments, the grain size may be between about 0.2 μm and about 0.5 μm, between about 0.5 μm and about 1 μm, between about 1 μm and about 1.5 μm, between about 1.5 μm and about 2 μm, between about 2 μm and about 2.5 μm, or between about 2.5 μm and about 3 μm. The average grain size may be between about 0.5 μm and about 2 μm. The average grain size may be more than about 0.2 μm. The grain boundary may be less than about 3 μm. When the metal is iron, the metal deposit may be especially crystalline, where the grain boundaries lie between different crystals in the metal deposit.
Metal deposits produced using methods disclosed herein are surprisingly pure, where atomic elements from the electrolyte other than the metal are not substantially incorporated into the metal deposit. The metal deposit may contain less than about 5 mol % oxygen, such as less than about 4 mol %, less than about 3 mol %, less than about 2 mol %, less than about 1 mol %, less than about 0.5 mol %, less than about 0.1 mol %. The metal deposit may contain less than about 5 mol % carbon, such as less than about 4 mol %, less than about 3 mol %, less than about 2 mol %, less than about 1 mol %, less than about 0.5 mol %, less than about 0.1 mol %. The metal deposit may contain less than about 5 mol % chlorine, such as less than about 4 mol %, less than about 3 mol %, less than about 2 mol %, less than about 1 mol %, less than about 0.5 mol %, less than about 0.1 mol %. In particular embodiments, the metal deposit may contain less than about 5 mol % of each oxygen, carbon and chlorine, such as less than about 4 mol %, less than about 3 mol %, less than about 2 mol %, less than about 1 mol %, less than about 0.5 mol %, less than about 0.1 mol %. These mole percentages may be determined using any method known in the art, including for example electron-dispersive spectroscopy (EDS).
Compositions are disclosed herein which were used as electrolytes in the methods. Broadly, these compositions may comprise a trialkylamine halide, carboxamide, and a metal source. In particular embodiments, these compositions may consist essentially of trialkylamine chloride, carboxamide, and a metal salt. That is, the electrolyte may be of a composition where the trialkylamine halide is a trialkylamine chloride and the metal source may be a metal salt. In another example, the compositions may comprise trialkylamine chloride and carboxamide in molar ratio between 1:1 and 1:30 to form an ionic liquid, wherein the trialkylamine chloride is trimethylamine chloride (TMACl), triethylamine chloride (TEACl), or combinations of the two. In various embodiments, the metal salt may have the formula MXy, wherein M is a metal, X is a halide, and y is an oxidation number of M. The metal salt may be in a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid. Any metal salt MXy described herein is suitable for use in these compositions. Also, any variation of the ranges of molar ratios or concentrations described herein are suitable for these compositions. These compositions encompass any molar ratio, metal salt, or concentration of metal salt described herein.
In particular, the composition may consist essentially of trimethylamine/triethylamine chloride, a carboxamide of Formula (I), and iron chloride. Generally, the trimethylamine/triethylamine chloride and carboxamide may be in molar ratio between 1:1 and 1:30 to form an ionic liquid. In various embodiments, the trimethylamine/triethylamine halide and carboxamide may be in molar ratio between about 1:1 and about 1:2, between about 1:2 and about 1:3, between about 1:3 and about 1:4, between about 1:4 and about 1:5, between about 1:5 and about 1:6, between about 1:6 and about 1:7, between about 1:7 and about 1:8, between about 1:8 and about 1:9, between about 1:9 and about 1:10, between about 1:10 and about 1:11, between about 1:11 and about 1:12, between about 1:12 and about 1:13, between about 1:13 and about 1:14, between about 1:14 and about 1:15, between about 1:15 and about 1:16, between about 1:16 and about 1:17, between about 1:17 and about 1:18, between about 1:18 and about 1:19, between about 1:19 and about 1:20, between about 1:20 and about 1:21, between about 1:21 and about 1:22, between about 1:22 and about 1:23, between about 1:23 and about 1:24, between about 1:24 and about 1:25, between about 1:25 and about 1:26, between about 1:26 and about 1:27, between about 1:27 and about 1:28, between about 1:28 and about 1:29, or between about 1:29 and about 1:30.
The trimethylamine/triethylamine halide and carboxamide may be in molar ratio of greater than about 1:2, such as greater than about 1:5. The trimethylamine/triethylamine halide and carboxamide may be in molar ratio of less than about 1:30, such as less than about 1:20, or less than about 1:10. In particular, the trimethylamine/triethylamine halide and carboxamide may be in molar ratio of about 1:2. The trimethylamine/triethylamine halide and carboxamide may also be in molar ratio of about 1:5. Alternatively, the trimethylamine/triethylamine halide and carboxamide may be in molar ratio of about 1:10.
In particular, the carboxamide may be urea, wherein the trimethylamine/triethylamine halide and urea may be in molar ratio of greater than about 1:2, such as greater than about 1:5. The trimethylamine/triethylamine halide and urea may be in molar ratio of less than about 1:30, such as less than about 1:20, or less than about 1:10. In particular, the trimethylamine/triethylamine halide and urea may be in molar ratio of about 1:2. The trimethylamine/triethylamine halide and urea may also be in molar ratio of about 1:5. Alternatively, the trimethylamine/triethylamine halide and urea may be in molar ratio of about 1:10.
Generally, the iron chloride may be in a concentration between about 0.2 and about 1.5 moles per liter of the ionic liquid; that is, between about 0.2 M and about 1.5 M. In various embodiments, the iron chloride may be at a concentration between about 0.2 M and about 0.25 M, between about 0.25 M and about 0.3 M, between about 0.3 M and about 0.35 M, between about 0.35 M and about 0.4 M, between about 0.4 M and about 0.45 M, between about 0.45 M and about 0.5 M, between about 0.5 M and about 0.55 M, or between about 0.55 M and about 0.6 M. The concentration of iron chloride may be more than about 0.2 moles per liter of the ionic liquid. The concentration of iron chloride may be less than about 1.5 moles per liter of the ionic liquid. In particular, the concentration of iron chloride may be about 0.3 moles per liter of the ionic liquid.
In some embodiments, the composition may consist of trimethylamine/triethylamine chloride, carboxamide and iron chloride. These compositions encompass the molar ratios and concentrations of metal salt described herein
The compounds described herein have asymmetric centers. Compounds of the present disclosure containing an asymmetrically substituted atom may be isolated in optically active or racemic form. All chiral, diastereomeric, racemic forms and all geometric isomeric forms of a structure are intended, unless the specific stereochemistry or isomeric form is specifically indicated.
When introducing elements of the present disclosure or the embodiments(s) thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Two ionic liquids were prepared by mixing triethylamine hydrochloride or trimethylamine hydrochloride with urea in a 1:2 molar ratio at 110° C. Iron electrodeposition used of these ionic liquids at different potentials, current densities, and varying concentrations of iron chloride (FeCl3) under ambient conditions and variable temperature. A Gamry™ Reference 3000 potentiostat/galvanostat/zero-resistance ammeter was employed to conduct the electrochemical experiment within a three-electrode electrochemical cell. The electrochemistry of ionic liquids with and without FeCl3 were investigated using a glassy carbon (geometric area of about 0.07 cm2) working electrode, Pt wire counter electrode, and a Pt electrode reference electrode. Iron was deposited onto mild steel substrates, which were prepared by washing sequentially with 2-propanol, 6 M HCl(aq) and deionized water. In these measurements, an iron plate was used as the counter and reference electrodes.
To examine the surface morphology and elemental compositions of the metal deposits, a Phenom™ XL scanning electron microscope (SEM) with energy-dispersive spectrometer (EDS) working at 15 kV was used. The EDS detector had a resolution of about +/−1%.
Cross-sections of samples were prepared using a Buehler low speed saw with 4″ diamond blade, followed by sequential polishing with 400, 800, 1000, and 1500 grit paper. Current efficiencies were calculated by comparing the total charge (coulomb) of deposition to the net mass change of the substrate.
Referring to
Referring to
“Overpotential” refers to the energy deviation from an electrode's equilibrium potential necessary to initiate a particular reaction. The equilibrium potential accounts for the surface reaction at the electrode if no external energy is applied and is set to V=0. The overpotential is then the equilibrium potential plus the change (V+ΔV), necessary to shift the surface reactions away from equilibrium and toward iron deposition.
The nucleation loop occurs because of the energetic difference between a bare surface (initial surface) and a surface on which some Fe atoms have already nucleated. As more negative potentials are scanned with an initial, smooth surface, the current at X volts past the overpotential is low. Once some iron is deposited, the energy barrier to deposit even more decreases. As such, when X volts is reached in a scan over the other direction, the current is higher in magnitude because of that lower energy barrier.
Referring to
Referring to
Through several series of SEM images, the average grain size of the deposited metals is shown to depend on the characteristics of the electric potential used, including its current density and the voltage of the reducing potential.
The effect of iron salt concentration in the electrolyte was measured at a constant current density.
Referring to
The reduction potential experiment was repeated for the 1:2 (mol/mol) TMACl/urea ionic liquid with a concentration of 0.3 M FeCl3. Referring to
The metal deposits formed following Examples 1 and 2 were exceptionally pure, having very low carbon, oxygen, and chlorine contents.
Furthermore,
The cross-sections of
Referring to
The molar ratios of trialkylamine halide and urea between 1:1 and 1:30 were explored. SEM data indicated that iron was deposited using any ratio of TEACl/urea or TMACl/urea tested, but that the properties of the electrolyte and the deposit varied. At ratios above 1 TEACl to 30 urea, components had difficulty solubilizing homogeneously. Morphology shifted more toward two-dimensional growth across the surface of the substrate when urea ratios increased, demonstrating the role of urea in reducing dissolved iron. As more urea complexed with Fe from anodic stripping or from FeCl3, the overpotential of Fe(II) to the Fe0 deposit decreased. The positive shift of overpotential was greater for triethylamine than for trimethylamine (which had a lower overpotential initially).
When the urea concentration was increased to a molar ratio of 1:10 TEACl/urea, the mixture was liquid and had lower viscosity than the 1:2 ionic liquid. The reduction peak of Fe(II) to Fe0 also shifted to more positive (
The potentials used for iron deposition were tested from 1:10 (mol/mol) TEACl/urea with 0.3 M FeCl3 on steel substrates: −1.0 V (
As seen at
Referring to
Without wishing to be bound by theory, the active species for deposition of iron was the urea-FeClx complex. TEA-HCl or TMA-HCl disrupted the crystallization of this complex to allow dissolution at lower temperatures. TEA-HCl added some conductivity to the solution by supplying CF ions, but the biggest impact was due to lowering the solution viscosity to increase ion mobility. Because the conductivity remained high and similar among all ratios tested, most of the charge-carrying species originated from FeCl3.
Higher ratios of urea to trialkylamine generally resulted in deposits of higher density and better adhesion. Again, without wishing to be bound by theory, adhesion between a deposited layer and the substrate might fail due to impurities at the interface, crystalline differences, and the like, resulting in delamination of the deposited material from the substrate. In these deposits, however, growth is highly epitaxial with a nearly homogenous interface, making delamination unlikely. So the next most likely mechanism of failure is stored stresses in the high-density deposit itself, leading to cracks roughly perpendicular to the substrate's surface. Crack propagation eventually causes portions of material to fall off of the substrate. This stress may be relieved while maintaining excellent adhesion (that is, low delamination probability) by using an ionic liquid with a 1:5 molar ratio, or by using a conventional ON/OFF pulsing program during deposition, where Time-ON>>Time OFF.
Scanning electron microscopy showed that different metals could be deposited from the 1:2 (mol/mol) TMACl/urea ionic liquid by stripping different metals from a pressed powder anode, the sole provider of metal for these experiments.
The pressed anodes were made from metal powders of varying size distribution were mixed together in a vial at selected ratios and then added to a 13-mm diameter pellet die. The interior of the die was evacuated using a vacuum line. The entire die is placed into a hand-operated press. The die was gradually pressed to a final load of 10 tons and held for about 30 minutes to allow compaction of the powder into a solid shape. Pellets could then be removed from the die with final dimensions of about 13-mm diameter and depth between about 3 mm and about 6 mm.
These pellets were seated in a custom-built polyterfluroroethylene (PTFE) electrode holder. The holder contained a seated cover so that, when in operation, exposed 11 mm of the diameter of the pellet to the electrolyte. A wire ran from electrical contact with the pellet through to the top of the holder. When assembled, the holder was configured to be placed into the electrolyte and operated as an electrode.
Besides urea, other carboxamides of Formula (I) described herein may be used for complexing metals, having similar solution melting points and performance when combined with a trialkylamine and FeCl3. For example,
Those skilled in the art will appreciate that the presently disclosed embodiments teach by way of example and not by limitation. Therefore, the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.
the carboxamide comprising Formula (I):
This divisional application is related to and claims priority to U.S. patent application Ser. No. 15/293,096, filed Oct. 13, 2016 entitled “Metal Deposits, Compositions, and Methods for Making the Same,” the entire contents of which is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15293096 | Oct 2016 | US |
| Child | 16438077 | US |
