WO2022185098A1

WO2022185098A1 - Electrolytic process for producing a nanocrystalline carbon with 1 d, 2d, or 3d structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite and/or a mixture thereof at ambient conditions

Info

Publication number: WO2022185098A1
Application number: PCT/IB2021/051792
Authority: WO
Inventors: Joongjai PANPRANOT; Rungkiat NGANGLUMPOOM; Thapong TEERAWATANANOND; Sutasinee WATMANEE; Piriya PINTHONG; Krongkwan POOLBOON; Nattaphon HONGRUTAI; Duangamol TUNGASMITA; Sukkaneste TUNGASMITA; Yuttanant Boonyongmaneerat; Piyasan Praserthdam
Original assignee: Crystallyte Co., Ltd.
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2022-09-09
Also published as: WO2022185166A1; WO2022185167A4; WO2022185167A1; WO2022185166A4

Abstract

A new process for producing nanocrystalline carbon with a 1D, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof, by electrochemically reducing a carbon oxide under ambient conditions at an onset potential not greater than 10 Volt in presence of an electrolyte and at least one electrode, said electrode comprising a metallic material comprising one or more of the following: a post-transition element, a transition element, an oxide, or an alloy thereof. The ambient conditions and the onset potential enabled by embodiments simplify the production, and the nanocrystalline carbon yield can be scaled up to reach a mass production scale. A product obtained from the new process comprises a nanocrystalline carbon with a 1D, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal. Such product can be a mixture that contains various carbon structures, comprising: a nanocrystalline diamond, an amorphous carbon, a graphitic carbon, and a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal. Said product may further comprise a graphite or a graphene. Products according to the embodiments contain substantially more types of structure, and so are more versatile than those currently commercially available.

Description

TITLE OF THE INVENTION

ELECTROLYTIC PROCESS FOR PRODUCING A NANOCRYSTALLINE CARBON WITH 1 D, 2D, OR 3D STRUCTURE AND/OR A NANOCRYSTALLINE DIAMOND AND/OR AN AMORPHOUS CARBON AND/OR A METAL-CARBON NANOMATERIAL COMPOSITE AND/OR A MIXTURE THEREOF AT AMBIENT

CONDITIONS

FIELD OF INVENTION

The present disclosure relates to the production of a carbon nanomaterial, including a 5 nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or transition metal, and/or a mixture thereof, particularly when said production of carbon nanomaterials involves electrochemical reduction.

BACKGROUND OF THE INVENTION

10 Carbon nanomaterials, including a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or transition metal, and/or a mixture thereof, are versatile materials that have technically desirable properties (e.g. high surface area, high conductivity, strength, and many more). Their various applications include 15 those in electronics and medical industries. In the recent decades, the demand for carbon nanomaterials has been growing significantly.

However, carbon-based nanoparticles in nature exist only in negligible quantities and thus cannot satisfy the demand. Most of carbon nanomaterials used in the industries are artificially produced or synthesized. 0 The conventional methods of industrially producing said carbon nanomaterials include pyrolysis, Chemical Vapor Deposition (CVD), arc discharge, laser ablation, and exfoliation, each of which having their major shortcomings. The pyrolysis and CVD methods are known to release a large amount of carbon emission. Electrochemical exfoliation requires a high temperature at about 550 °C which, in turn, results in a high production cost. Arc discharge 5 require a suitable liquid medium to be effective. Furthermore, these conventional methods are energy-intensive. Further, a variant of metal-carbon nanomaterial (so-called “Covetics”) exhibits improvement mechanical property. These variants are conventionally produced by melting the metal inside a graphite crucible in an induction furnace. This process requires an extreme conditions including high temperature in order to melt the metal host.

US patent publication No. US20160115601 A1 discloses a process of producing graphene and/or graphite nanoplate structures by the electrochemical reduction of carbon oxide in an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte. The reduction occurs at the operating temperature not exceeding 110 °C. Nonetheless, the potential difference across the electrodes can be up to 30 V for dissociating the strong C=0 bond, which still requires a high energy and thus a high production cost.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new process for industrially producing the carbon nanomaterials and their abovementioned variants. The inventor has found that embodiments according to the concept of the present invention enable the production of such products at a significantly less energy-intensive condition.

In the first and second aspects, the present invention provides a new process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof. The embodiments’ characterizing features allow said process to be carried out under ambient conditions and at an onset potential not greater than 10 Volt. Said conditions, which simplify the production, are effects that distinguishes a process in accordance with the present invention from the currently available ones. The metal-carbon nanomaterial composite product yield per a single run of an embodiment depends on the type of metal electrode and reaction time of a batch and is approximately 20-50 mg cm^ h ¹, which is conducive to the scale-up to a mass production scale.

An embodiment in accordance with the first aspect is a process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof. Said process is carried out by electrochemically reducing a carbon oxide under ambient conditions at an onset potential not greater than 10 Volt in presence of an electrolyte and at least one electrode. Said electrode comprises a metallic material comprising one or more of the following: a post-transition element, a transition element, an oxide, and an alloy thereof.

Preferably, the metallic material comprises one or more of the post-transition element and the transition element.

Preferably, said at least one electrode is formed of said metallic material in the particulate form deposited upon a substrate.

Optionally, said at least one electrode is formed of said metallic material in the form of a metallic foil. In such case, the deposition of particulate metal is not required.

Preferably, the post-transition element is Bi, Sn, or Pb and the transition element is Zn, Co, or Ag.

Even more preferably, the electrode that is formed of the foregoing metallic material is a cathode.

Preferably, the electrolyte is separated into an anolyte and a catholyte. Even more preferably, the electrolyte is separated by a membrane.

Preferably, the anolyte is an aqueous solution. Said aqueous solution comprises potassium bicarbonate (KHCO3) and water.

Preferably, the catholyte is a mixture containing an ionic liquid and a solvent. Said ionic liquid comprises 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim] [BF4]) and said solvent comprises a mixture of (i) water and (ii) either ethylene glycol (EG) or propylene carbonate (PC).

Optionally, the anolyte and catholyte are the same electrolyte, which is a mixture containing an ionic liquid and a solvent.

Optionally, the carbon oxide is supplied to the electrolyte by way of pre-dissolving or pre-solvating the carbon oxide in the electrolyte before the electrochemical reduction. Also optionally, the carbon oxide is supplied to the electrolyte during the electrochemical reduction by way of continuous dissolving or bubbling. Preferably, the carbon oxide is supplied to the electrolyte by way of pre-dissolving or pre-solvating the carbon oxide in the electrolyte before the electrochemical reduction and during the electrochemical reduction by way of continuous dissolving or bubbling.

Preferably, the nanocrystalline carbon with the ID, 2D, or 3D structure and/or the nanocrystalline diamond and/or the amorphous carbon and/or the metal-carbon nanomaterial composite, said composite containing the post-transition or the transition metal, and/or the mixture thereof, is formed at the cathode. An embodiment in accordance with the second aspect is a process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof. Said process comprises steps of: depositing a metallic material in the particulate form on a substrate to form a cathode; and electrochemically reducing carbon dioxide in presence of (i) an electrolyte that is separated into an anode region and a cathode region, (ii) an anode submerged in said anode region, and (iii) said cathode submerged in said cathode region. Said electrolyte comprises a mixture of 1 -butyl - 3-methylimidazolium tetrafluoroborate ([bmim][BF4]), water, and either ethylene glycol (EG) or propylene carbonate (PC). And said electrochemically reducing the carbon dioxide occurs in an ambient condition at an onset potential not greater than 10 Volt.

Preferably, said metallic material is Zn, and said substrate is a Cu foil.

Also preferably, said metallic material is Bi, and said substrate is a Sn foil.

Also preferably, said metallic material is Sn, and said substrate is a Cu foil.

Also preferably, said metallic material is Co, and said substrate is a Cu foil.

Also preferably, said metallic material is Ag, and said substrate is a Cu foil.

Also preferably, said metallic material is a Pb foil.

Among possible combinations of metallic materials and substrates, the present inventor found that the foregoing combinations enable markedly greater yields.

In the third and fourth aspects, the present invention provides a new product that is obtainable from the abovementioned first or second aspects.

An embodiment in accordance with the third aspect is a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal. Said embodiment is obtainable from any embodiment in accordance with the first or second aspect.

Preferably, said nanocrystalline carbon with the ID, 2D, or 3D structure and/or the nanocrystalline diamond and/or the amorphous carbon and/or the metal-carbon nanomaterial composite, said composite containing the post-transition or the transition metal product, also comprises a graphitic carbon having an average crystallite domain size within a range of 1-100 nm.

An embodiment in accordance with the fourth aspect is a product that is a mixture having various carbon structures comprising: a nanocrystalline diamond, an amorphous carbon, a graphitic carbon, and a metal-carbon nanomaterial composite, said composite containing a post transition or a transition metal. Said product is obtainable from any embodiment in accordance with the first or second aspect.

Preferably, said product comprises a graphitic carbon having an average crystallite domain size within a range of 1-100 mm.

Also preferably, the various carbon structures further comprise a graphite or a graphene.

Accordingly, the present disclosure provides examples to illustrate the conditions of such processes and the characteristic properties of such products. The preferred embodiments will be described in detail later on.

BRIEF DESCRIPTION OF DRAWINGS

Fig 1 shows a schematic diagram of an electrochemical cell for electrochemically reducing carbon oxide in accordance with a preferred embodiment (not to scale).

Fig 2 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 1.

Fig 3 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 2.

Fig 4 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 3.

Fig 5 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 4.

Fig 6 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 5.

Fig 7 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 6.

Fig 8 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 7.

Fig 9 shows a Raman spectrum exhibiting merged peaks of a product obtained from Example 8.

DETAILED DESCTIPTION OF EMBODIMENTS OF THE INVENTION It is to be understood that the following detailed description will be directed to embodiments, provided as examples for illustrating the concept of the present invention only. The present invention is in fact not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of this invention will be limited only by the appended claims.

The detailed description of the invention is divided into various sections only for the reader’s convenience and disclosure found in any section may be combined with that in another section.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

The term “about” when used before a numerical designation, e.g., dimensions, time, amount, and such other, including a range, indicates approximations which may vary by ( + ) or ( - ) 10 %, 5 % or 1 %, or any sub-range or sub-value there between.

“Comprising” or “comprises” is intended to mean that the compositions and processes include the recited elements, but not excluding others. “Consisting essentially of’ when used to define compositions and methods, shall mean excluding other elements of any essential significance to the combination for the stated purpose. Thus, a process or product consisting essentially of the elements as defined herein would not exclude other materials or steps that do not materially affect the basic and novel characteristic(s) of the claimed invention. “Consisting of’ shall mean excluding more than trace elements of other ingredients and substantial steps. Embodiments defined by each of these transition terms are within the scope of this invention.

A preferred embodiment is a new process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal -carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof, by electrochemically reducing carbon oxide. The process is configured to occur under ambient conditions at an onset potential not greater than 10 Volt in presence of an electrolyte and at least one electrode comprising a metallic material.

Electrochemical reduction

In a preferred embodiment, the carbon oxide is electrochemically reduced in an electrochemical cell comprising a receptacle, at least one electrode, an electrolyte, and a membrane separating the electrolyte into regions. Electrochemical cell

Fig 1 shows a schematic diagram of an electrochemical cell in which a process for producing a carbon nanomaterial is conducted in accordance with a preferred embodiment. The electrochemical cell (10) comprises a receptacle (100) and a membrane (200) which separates the receptacle (200) into an anode region (300) and a cathode region (400). The receptacle (100) receives and contains an electrolyte which is in turn separated by the membrane (200) into an anolyte (310) and a catholyte (410) contained the anode region (300) and the cathode region (400), respectively. This arrangement allows options whereby the anolyte (310) and catholyte (410) to be either the same or different substances. Further, this preferred electrochemical cell is a 3 -electrode system wherein electrodes (320, 420, 430) are immersed in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode is an anode (320). The anode region (300) further comprises a vent (350) to provide a passage of oxygen out from the anode region (300). Preferably, the vent (350) is located at the upper part or top of the anode region (300). In the cathode region (400), the electrodes comprise a cathode (420) and a reference electrode (430). The cathode region (400) further comprises a feed (440) to provide a passage of the carbon oxide into the cathode region (400), and a vent (450) to provide a passage of the carbon oxide out from the cathode region (400). Preferably, the feed (440) is located at the lower part or bottom of the cathode region (400) and the vent (450) is located at the upper part or top of the cathode region (400) to be conducive to continuous bubbling or dissolving arrangement. The electrodes (320, 420, 430) are electrically connected to a power supply (500), which according to a preferred embodiment is a source of direct current electricity.

Carbon oxide

According to the concept of the present invention, a carbon oxide refers to any oxide of carbon such as carbon monoxide, carbon dioxide, or a mixture thereof. Preferably, the carbon oxide is carbon dioxide because of its ubiquity and low price. The carbon oxide may be supplied to the electrolyte (310, 410) in any desired form, for example, in solid, liquid, gaseous, or solvated form. Preferably, the carbon oxide is supplied to the electrolyte (310, 340) in the gaseous form. The carbon oxide may be supplied to the electrolyte (310, 340) before or during the electrochemical reduction, or both, which is a preferable arrangement.

Supplying the carbon oxide to the electrolyte (310, 340) before the electrochemical reduction is preferably carried out by way of pre-dissolving or pre-solvating the carbon oxide in the electrolyte (310, 410). More preferably, the pre-dissolving or pre-solvating is carried out until the electrolyte (310, 410) is saturated with the carbon oxide at a given temperature and pressure.

Supplying the carbon oxide to the electrolyte (310, 340) during the electrochemical reduction is preferably carried out by continuous dissolving or bubbling. Preferably, the supply is carried out by bubbling. Preferably, the bubbling flow rate is within the range of about 1 to about 1,000 cm³/min. More preferably, the bubbling flow rate is within the range of about 1 to about 200 cm³/min.

The carbon oxide is supplied to the electrolyte (310, 340) at a bubbling flow rate which depends on a liquid volume contained in the receptacle (100). In an embodiment where said liquid volume is within the range of about 10 to about 1,000 cm³, the preferred bubbling flow rate is within the range of about 1 to about 1,000 cm³/min. In another embodiment where said liquid volume is within the range of about 15 to about 25 cm³, the preferred bubbling flow rate is within the range of about 1 to about 200 cm³/min.

Pressure

A process according to the concept of the present invention may be carried out in various conditions which may be adjusted according to the circumstantial requirements. The applicable pressure is within a range of about 1 to about 20 atm.

The pressure in accordance with the preferred embodiment is an ambient pressure. The ambient pressure refers to a common or usual condition surrounding any person. An ambient pressure for operating the process is preferably 1 atm. Because a process in accordance with the preferred embodiment allows the electrochemical reduction to occur effectively at such ambient pressure, it obviates the need to pressurize, depressurize, vacuumize or control the pressure at any part of the electrochemical cell (10) and thus substantially simplify the production.

Temperature

A process according to the concept of the present invention may be carried out in various conditions which may be adjusted according to the circumstantial requirements. The applicable temperature is within the range from about 10 °C to about 60 °C.

The temperature in accordance with the preferred embodiment is an ambient temperature . The ambient temperature refers to a common or usual condition surrounding any person in a room. Preferably, the ambient temperature is within a range of about 15 °C to about 50 °C. More preferably, the ambient temperature is about 30 °C. Because a process in accordance with the preferred embodiment allows the electrochemical reduction to occur effectively at such ambient temperature, it obviates the need to heat, cool or control the temperature at any part of the electrochemical cell (10) and thus substantially simplify the production.

Onset potential

Generally, the onset potential of the electrochemical cell (10) is at least of the electric potential sufficient to initiate the electrochemical reduction of the carbon oxide. Preferably, the onset potential across the electrodes (320, 420, 430) is substantially constant during the electrochemical reduction.

The onset potential of the electrochemical cell (10) depends on the electrode being selected. In an embodiment, the electrochemical cell (10) comprises a power supply (500) to provide the onset potential, which is preferably within a range of about 0.1 to about 10 V, more preferably within a range of about 0.9 to about 3 V, and even more preferably at about 1.5 V.

Preferably, the power supply (500) is adapted to monitor the onset potential. Even more preferably, the power supply (500) is adapted to regulate the onset potential to be in accordance with a preset value. In the following Examples, the power supply (500) is a potentiostat which is capable of both monitoring and regulating the onset potential. A potentiostat’ s equivalent devices for an industrial scale production include rectifier which is as well applicable to the concept of the present invention.

Electrolyte

According to the concept of the present invention, an electrolyte, which may be separated into an anolyte (310) and a catholyte (410), is an ion-containing fluid. Preferably, the anolyte (310) is an aqueous electrolyte and the catholyte (410) is a mixture containing an ionic liquid and a solvent. Optionally, the anolyte (310) and the catholyte (410) are the same electrolyte, which is a mixture comprising an ionic liquid.

The ionic liquid can be any salt having a melting point below the ambient temperature used in the process, and thus is in its liquid state at said ambient temperature.

According to the concept of the present invention, all known ionic liquids may be part of the mixture that forms the electrolyte. Preferably, the ionic liquids used as electrolyte in an embodiment are compounds represented by formula (I):

[A]n⁺ [Y]n - (I) wherein: n is 1 or 2; [Y]n is selected from the group comprising tetrafluoroborate ([BF4] ), hexafluorophosphate ([PF6] ), halides (CP, Br , F , G), hexafluoroantimonate ([SbF6] ), and nitrate ([NO3] ); [A]⁺ is selected from the group comprising quaternary ammonium cations and imidazolium cations represented by the formula (II)

wherein the imidazole ring may be substituted with one or more groups selected from Cl-C6-alkyl, Cl-C6-alkoxy, Cl-C6-aminoalkyl, C5 -Cl 2-aryl, and C5-C12-aryl-Cl-C6-alkyl groups.

Further, [A]⁺may also be cations in accordance with pyridinium, pyrazolium, triazolium, or pyrrolidium, represented by formulas (III), (IV), (V), and (VI), respectively:

In some embodiments, the solvent is selected from the group comprising water, cyclic carbonate such as propylene carbonate (PC), ethylene carbonate (EC), styrene carbonate, glycerol carbonate, glycol such as ethylene glycol (EG), propylene glycol (PG), polymeric glycol and a mixture thereof.

According to an embodiment, the preferred combination of the ionic liquid and the solvent is as follows: the ionic liquid is 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim][BF4]) and the solvent is a mixture of (i) water and (ii) either EG or PC.

In some embodiments, the solvent also functions as a stabilizer of nanoparticles/carbon nanomaterial formed at the at least one electrode during the electrochemical reduction of carbon oxide in the electrochemical cell (10). Preferably, the solvent is selected from water, PC, and EG. More preferably, the solvent is a mixture of water, PC, and EG.

According to the concept of the present invention, the anolyte may also be an aqueous solution. Preferably, the anolyte that is an aqueous solution comprises a salt as a solute and water as solvent. According to an embodiment, the preferred aqueous solution contains a cation comprising Na⁺, K⁺, or Cs⁺ and an anion comprising HCO3 , SO4² , or Cl .

In some embodiments, the aqueous electrolyte is potassium bicarbonate (KHCO3).

Membrane

In the present disclosure, a membrane (200) is present to separate the receptacle (100) into an anode region (300) and a cathode region (400), and thus the electrolyte into the anolyte (310) and the catholyte (410), in order to prevent oxidation of the carbon nanomaterial in the electrolyte (310, 410). The membrane (200) further prevents the gaseous anodic products, such as oxygen, from mixing with the gaseous cathodic products, such as hydrogen, and enhances the transportation of proton (EE) from the anode region (300) to the cathode region (400). Preferably, the membrane (200) arranged thus causes the contents of the two regions (300, 400) to have different pH conditions.

In one embodiment, the membrane (200) comprises a polymer fdm. Preferably, the membrane (200) is a proton-conductive membrane made of a polymer film which allows the transportation of proton only. Preferred examples of such proton-conductive membrane include those commercially available under the tradename ofNAFION™, specifically NAFION™ 961, NAFION™ 430, or NAFION™ 117.

Electrode

According to an embodiment, an electrode in the electrochemical cell (10) is categorized into a cathode (420), and/or an anode (320). The cathode (420) is an electrode having more negative potential than the other electrode, while the anode (320) is an electrode having less negative potential than the other electrode.

Preferably, at least one electrode is formed of the metallic material in the particulate form deposited upon a substrate, or formed of the metallic material in the form of metallic foil without further deposition of particulate metal. Preferably, said electrode, being formed of the metallic material in either of the foregoing forms, is the cathode (420).

The metallic material in the particulate form can be deposited upon the substrate by means of any deposition method such as electrodeposition, chemical vapor deposition, and thin- fdm deposition, carried out in an ambient condition. Preferably, the metallic material in the particulate form is deposited upon the substrate by means of electrodeposition carried out under ambient conditions. Preferably, the solution used in the electrodeposition contains the metallic material intended to be deposited upon the substrate, which may be in any form or derivatives including ions and radicals.

The metallic material being deposited upon the substrate in accordance to an embodiment is selected from one or more of the following: a post-transition element, a transition element, an oxide, and an alloy thereof. Preferably, the metallic material being deposited upon the substrate is selected from one or more of the following: a post-transition element, and a transition element. More preferably, the post-transition element is bismuth (Bi) or tin (Sn); and the transition element is zinc (Zn), cobalt (Co), or silver (Ag).

The substrate upon which the metallic material in the particulate form is deposited can also be a metal sheet such as a metal foil, including a copper (Cu) foil, tin (Sn) foil, titanium (Ti) foil, or a non-metal sheet such as glass sheet, or a rigid body of aluminum (Al), silicon (Si), carbon (C), etc. Preferably, the substrate is a metal foil. More preferably, the substrate is a copper (Cu) foil, tin (Sn) foil, bismuth (Bi) foil, aluminum (Al) foil, or titanium (Ti) foil.

The electrode (cathode) is left in natural air or oxygen-containing atmosphere at the room temperature to create a thin oxide layer prior to the start of the electrochemical reduction reaction.

Detail of the deposition of the metallic material upon the substrate will be exemplified in Example 1.

In an embodiment where the electrode is formed of the metallic material in the form of metallic foil, said metallic foil is preferably a lead (Pb) foil.

In some embodiments, at least one electrode is essentially free of a carbon-based material before carbon oxide is reduced electrochemically. Preferably, said electrode is the cathode (420).

In some embodiments, the substrate is configured to have a certain size, and/or shape in order to provide a greater specific surface area, upon which more metallic material in the particulate form may be deposited.

Preferably, the anode (320) is a platinum foil, platinum mesh, platinum rod, or graphite rod. More preferably, the anode (320) is a platinum mesh, platinum rod or a graphite rod.

In some embodiments, the electrochemical cell further comprises a reference electrode (430) to provide a 3-electrode cell system. Preferably, the reference electrode (430) is an Ag/AgCl electrode.

Reaction time According to an embodiment, the electrochemical reduction occurring in the electrochemical cell (10) is a batch operation. The crystal structure and crystal size of the resulting product depends on the nature of electrode used, the energy supplied, and the reaction time, among others. Prolonging the reaction time results in a larger crystallite size being formed. According to the embodiments, the crystallite size is measured by Raman peaks.

According to the embodiments, the reaction time for each batch of production can be ranged from about 5 minutes to 140 minutes. Preferably, the reaction time for each batch of production is about 30 minutes to 70 minutes.

Nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof

In an embodiment, the process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal- carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or mixture thereof in the electrochemical cell (10) is preferably carried out as a batch operation.

The nanocrystalline carbon with the ID, 2D, or 3D structure and/or the nanocrystalline diamond and/or the amorphous carbon and/or the metal-carbon nanomaterial composite, said composite containing a post-transition or transition metal, and/or the mixture thereof is formed at at least one electrode. Preferably, said product is formed at the cathode (420).

The carbon product obtained from a process in accordance with a preferred embodiment comprises a graphite and/or a graphene and/or a graphitic carbon having an average crystallite domain size of about 1-100 nm and/or the nanocrystalline diamond and/or the amorphous carbon, and/or the metal-carbon nanomaterial composite, said composite containing the post transition or the transition metal, and/or the mixture thereof.

In some embodiments, the carbon product being produced is further separated from the electrode (320, 420) by a known separation process. Preferably, said separation process is a mechanical removal process, such as mechanical abrasion, or ultrasonication.

After being separated from the electrode (320, 420), the carbon product may contain residue of the metallic material originally deposited upon the electrode (320, 420). The metallic material can be further removed from the carbon product by means of a conventional chemical removal process, preferably acid leaching. Preferably, said acid leaching involves the use of Nitric Acid (HNO3), Hydrochloric Acid (HC1), or a mixture thereof. In some embodiments, the separation process of the carbon product from the electrode (320, 420) comprises the following steps:

(1) mechanically removing the solid product from the electrode (320, 420)

(2) placing solid product that was removed by step (1) in a microcentrifuge tube

(3) slowly dropping a mixture of nitric acid and hydrochloric acid into the microcentrifuge tube to perform acid leaching. Preferably, the mixture of nitric acid and hydrochloric acid is in a molar ratio of 1:3 in 0.3 ml of the solution

(4) shaking the solution before ultrasonicating the solution for approximately 5 minutes

(5) centrifuging the solution to separate the solid product from the solution

(6) collecting the solid product and neutralizing the solid product with deionized water (DI water). Preferably, the neutralization is conducted three times.

The abovementioned process results in a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon product and/or a metal- carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof, which is a mixture having various carbon structures. Said structures are inclusive of, and selectable from: an amorphous carbon, a graphite, a graphene, a nanocrystalline diamond, and a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal.

Examples of preferred embodiment

Example 1: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was fdled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Zn in its particulate form deposited upon a Cu foil as a substrate by means of electrodeposition in an ambient condition. ZnCh solution was used as the Zn precursor of said electrodeposition. The concentration of ZnCh was varied at about 0.001-10 M. Deposition time was about 10 - 7200 seconds. The electrode is left in natural air for 1-720 min before start the reaction. The electric current used for electrodeposition was set at about 10 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³ /min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.3 V.

After about 70 minutes of electrochemically reducing the carbon dioxide in the electrochemical cell (10), the carbon product was formed at the cathode (420), which was then removed from the catholyte (410) and dried.

The carbon product obtained from this Example was in the form of nanocrystalline carbon with a ID, 2D, and 3D structure that contained amorphous carbon, graphitic and graphite carbon structures. According to Fig. 2, specifically as calculated from the area of well-defined D-band and G-band under the shown Raman spectrum, the estimated average crystallite domain size of the graphitic carbon obtained from this Example was about 3.8 nm.

Example 2: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Bi in its particulate form deposited upon a Sn foil as a substrate by means of electrodeposition in an ambient condition of Example 1. Bi(NC>3)3 solution was used as the Bi precursor of said electrodeposition. The concentration of Bi(N03)3 was varied at about 0.001 - 1 M. Deposition time was about 60 - 3600 seconds. The electrode is left in natural air for 1- 720 min before start the reaction. The electric current used for electrodeposition was set at about 0.1 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³/min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.1 V.

The carbon product obtained from this Example was in the form of nanocrystalline carbon with a ID, 2D, and 3D structure that contained amorphous carbon, graphitic and graphite carbon structures. According to Fig. 3, specifically as calculated from the area of well-defined D-band and G-band under the shown Raman spectrum, the estimated average crystallite domain size of the graphitic carbon obtained from this Example was about 4.7 nm.

Example 3: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Sn in its particulate form deposited upon a Cu foil as a substrate by means of electrodeposition in an ambient condition of Example 1. SnCh solution was used as the Sn precursor of said electrodeposition. The concentration of SnCh was varied at about 0.001 - 1 M. Deposition time was about 60 - 3600 seconds. The electrode is left in natural air for 1-720 min before start the reaction. The electric current used for electrodeposition was set at about 0.1 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³/min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.5 V.

After about 70 minutes of the electrochemically reducing the carbon dioxide in the electrochemical cell (10), the carbon product was formed at the cathode (420), which was then removed from the catholyte (410) and dried.

The carbon product obtained from this Example was in the form of nanocrystalline carbon with a ID, 2D, and 3D structure that contained amorphous carbon, graphitic and graphite carbon structures. According to Fig. 4, specifically as calculated from the area of well-defined D-band and G-band under the shown Raman spectrum, the estimated average crystallite domain size of the graphitic carbon obtained from this Example was about 4.6 nm.

Example 4: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5:1:4 volume ratio of 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Co in its particulate form deposited upon a Cu foil as a substrate by means of electrodeposition in an ambient condition of Example 1. C0CI2 solution was used as the Co precursor of said electrodeposition. The concentration of C0CI2 was varied at about 0.001 - 1 M. Deposition time was about 60 - 3,600 seconds. The electrode is left in natural air for 1-720 min before start the reaction. The electric current used for electrodeposition was set at about 0.1 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³/min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.3 V.

The carbon product obtained from this Example was in the form of nanocrystalline carbon with a ID, 2D, and 3D structure that contained amorphous carbon, graphitic and graphite carbon structures. According to Fig. 5, specifically as calculated from the area of well-defined D-band and G-band under the shown Raman spectrum, the estimated average crystallite domain size of the graphitic carbon obtained from this Example was about 6.5 nm.

Example 5: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and ethylene glycol as an electrolyte and in presence of a three-electrode cell system.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³/min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat of about -1.1 V.

The carbon product obtained from this Example was in form of nanocrystalline carbon with ID, 2D, and 3D structure that contained amorphous, graphitic and graphite carbon structures. According to Fig. 6, specifically as calculated from the area of well-defined D-band and G-band under the shown Raman spectrum, the estimated average crystallite domain size of the graphitic carbon obtained from this Example was about 5.5 nm.

Example 6: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system. A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Ag in its particulate form deposited upon a Cu foil as a substrate by means of electrodeposition in an ambient condition of Example 1. Ag(NCh) solution was used as the Ag precursor of said electrodeposition. The concentration of AgfNCE) was varied at about 0.001 - 1 M. Deposition time was about 60 - 3600 seconds. The electrode is left in natural air for 1- 720 min before start the reaction. The electric current used for electrodeposition was set at about 0.1 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³/min for 30 minutes. To produce a carbon nanomaterial, the carbon dioxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.6 V.

After about 30 minutes of the electrochemically reducing the carbon dioxide in the electrochemical cell (10), the carbon product was formed at the cathode (420), which was then removed from the catholyte (410) and dried.

The metal-carbon composite product obtained from this Example was in the form of metallic Ag/Ag oxides and nanocrystalline carbon with a ID, 2D, and 3D structure. According to Fig. 7, as observed from the shown Raman spectrum, the carbon product obtained from this Example comprised nanocrystalline diamond, graphitic carbon, and amorphous carbon structures. Example 7: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of Ag in its particulate form deposited upon a Cu foil as a substrate by means of electrodeposition in an ambient condition of Example 1. Ag(NCh) solution was used as the Ag precursor of said electrodeposition. The concentration of AgfNCE) was varied at about 0.001 -1 M. Deposition time was about 60 - 3600 seconds. The electrode is left in natural air for 1-720 min before start the reaction. The electric current used for electrodeposition was set at about 0.1 mA - 10 A /cm². The reference electrode (430) was Ag/AgCl with a 3.5 mol/L potassium chloride (KC1) solution.

Carbon dioxide was then supplied to the electrochemical cell (10) and to the contained electrolyte at the bottom of the cathode region (400) by means of continuous bubbling at a flow rate of 100 cm³ /min for 30 minutes. To produce a carbon nanomaterial, the carbon oxide was electrochemically reduced under the following conditions: the pressure of about 1 atm; the temperature of about 30 °C ± 5 °C; the constant onset potential, as read from a potentiostat, of about -1.6 V.

After about 70 minutes of the electrochemically reducing the carbon dioxide in the electrochemical cell (10), the carbon product was formed at the cathode (420), which was then removed from the cathoylte (410) and dried.

The metal-carbon composite product obtained from this process was in the form of metallic Ag/Ag oxides and nanocrystalline carbon with a ID, 2D, and 3D structure. According to Fig. 8, as observed from the shown Raman spectrum, the carbon product obtained from this Example comprised nanocrystalline diamond, graphitic carbon, and amorphous carbon structures.

Example 8: Electrochemically reducing carbon dioxide in presence of a mixture of l-butyl-3-methylimidazolium tetrafluoroborate, water, and propylene carbonate as an electrolyte and in presence of a three-electrode cell system.

A process for producing a carbon nanomaterial took place in the electrochemical cell (10) comprising a receptacle (100) which was separated by a NAFION™ 117 membrane (200) into an anode region (300) and a cathode region (400). The cathode region (400) was filled with a catholyte (410) consisting essentially of a 5: 1:4 volume ratio of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF4]), water, and propylene carbonate, respectively. The anode region (300) was filled with an anolyte (310) consisting essentially of 0.1 M potassium bicarbonate (KHCO3). This electrochemical cell was a 3-electrode system wherein the electrodes (320, 420, 430) were submerged in, and thus in a direct contact with, the electrolyte (310, 410). In the anode region (300), the electrode was an anode (320) which is a platinum mesh. In the cathode region (400), the electrodes comprised a cathode (420) and a reference electrode (430). The cathode (420) was formed of a Pb foil that was free of further electrodeposited metallic particles. The electrode is left in natural air for 1-720 min before start the reaction.

The carbon-metal composite product obtained from this Example was in the form of crystalline lead carbonate [Pb(CC>₃)] that contained an amorphous carbon. According to Fig. 10, specifically, the amorphous carbon obtained from this Example was a sp²/sp³ hybridized carbon.

Fist of References

10 electrochemical cell 100 receptacle

200 membrane

300 anode region

310 anolyte 320 anode

350 vent 400 cathode region 410 catholyte 420 cathode 430 reference electrode

440 feed 450 vent

500 power supply

Claims

1. A process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof, by electrochemically reducing a carbon oxide under ambient conditions at an onset potential not greater than 10 Volt in presence of an electrolyte and at least one electrode, said electrode comprising a metallic material comprising one or more of the following: a post transition element, a transition element, an oxide, and an alloy thereof.

2. The process according to claim 1, wherein the metallic material comprises one or more of the post-transition element and the transition element.

3. The process according to claim 1, wherein said at least one electrode is formed of said metallic material in the particulate form deposited upon a substrate.

4. The process according to claim 1, wherein the post-transition element is Bi or Sn, and the transition element is Zn, Co, or Ag.

5. The process according to claim 1, wherein said at least one electrode is a metallic foil.

6. The process according to claim 5, wherein the metallic foil is a Pb foil.

7. The process according to claim 3, wherein the electrode that is formed of the metallic material in the particulate form deposited upon a substrate is a cathode (420).

8. The process according to claim 1, wherein the electrolyte is separated into an anolyte (310) and a catholyte (410).

9. The process according to claim 8, wherein the electrolyte (310, 410) is separated by a membrane (200).

10. The process according to claim 8, wherein said electrolyte (310, 410) is a mixture containing an ionic liquid and a solvent, said ionic liquid comprising a compound represented by formula (I):

[A]n⁺ [Y]n - (I), wherein: n is 1 or 2;

[Y]n is selected from the group comprising tetrafluoroborate ([BF4] ), hexafluorophosphate ([PF6] ), halides (CT. Br, F , T), hexafluoroantimonate ([SbF6] ), and nitrate ([NO3] );

[A]⁺ is selected from the group comprising:

(a) quaternary ammonium cations

(b) imidazolium cations represented by the formula (II)

wherein the imidazole ring of said formula (II) may be substituted with one or more groups selected from Cl-C6-alkyl, Cl-C6-alkoxy, Cl-C6-aminoalkyl, C5-C12-aryl, and C5-C12- aryl-Cl-C6-alkyl groups,

(c) cations in accordance with pyridinium, pyrazolium, triazolium, or pyrrolidium, represented by formulas (III), (IV), (V), and (VI), respectively:

and said solvent is selected from the group comprising water, cyclic carbonate, glycerol carbonate, glycol, polymeric glycol, and a mixture thereof.

11. The process according to claim 10, wherein said ionic liquid is l-butyl-3- methylimidazolium tetrafluoroborate ([bmim][BF4]).

12. The process according to claim 11, wherein said solvent comprises a mixture of (i) water and (ii) either ethylene glycol (EG) or propylene carbonate (PC).

13. The process according to claim 8, wherein said anolyte (310) is an aqueous electrolyte containing a cation comprising Na⁺, K⁺, or Cs⁺; and an anion comprising HCO3 , SO4² , or Cl .

14. The process according to claim 13, wherein the aqueous electrolyte comprises potassium bicarbonate (KHCO3) and water.

15. The process according to claim 8, wherein said catholyte (410) is a mixture containing an ionic liquid and a solvent, said ionic liquid comprising 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim] [BF₄]) and said solvent comprising a mixture of (i) water and (ii) either ethylene glycol (EG) or propylene carbonate (PC).

16. The process according to claim 1, wherein the carbon oxide is supplied to the electrolyte by way of pre-dissolving or pre-solvating the carbon oxide in the electrolyte before the electrochemical reduction.

17. The process according to claim 1, wherein the carbon oxide is supplied to the electrolyte during the electrochemical reduction by way of continuous dissolving or bubbling.

18. The process according to claim 1, wherein the carbon oxide is supplied to the electrolyte by way of pre-dissolving or pre-solvating the carbon oxide in the electrolyte before the electrochemical reduction and during the electrochemical reduction by way of continuous dissolving or bubbling.

19. The process according to claim 7, wherein the nanocrystalline carbon with the ID, 2D, or 3D structure and/or the nanocrystalline diamond and/or the amorphous carbon and/or the metal-carbon nanomaterial composite, said composite containing the post-transition or the transition metal, and/or the mixture thereof, is formed at said cathode (420).

20. A process for producing a nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, and/or a mixture thereof, said process comprising steps of: depositing a metallic material in the particulate form on a substrate to form a cathode (420); and electrochemically reducing carbon dioxide in presence of an electrolyte that is separated into an anolyte (310) and a catholyte (410), an anode (320) submerged in said anolyte (310) and said cathode (420) submerged in said catholyte (410), wherein said said catholyte (410) comprises a mixture of 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim][BF4]), water, and either ethylene glycol (EG) or propylene carbonate (PC), and said anolyte (310) comprises potassium bicarbonate and water. and wherein said electrochemically reducing the carbon dioxide occurs in an ambient condition at an onset potential not greater than 10 Volt .

21. A process according to claim 20, wherein said metallic material is Zn, and said substrate is a Cu foil.

22. A process according to claim 20, wherein said metallic material is Bi, and said substrate is a tin foil.

23. A process according to claim 20, wherein said metallic material is Sn, and said substrate is a Cu foil.

24. A process according to claim 20, wherein said metallic material is Co, and said substrate is a Cu foil.

25. A process according to claim 20, wherein said metallic material is Ag, and said substrate is a Cu foil.

26. A nanocrystalline carbon with a ID, 2D, or 3D structure and/or a nanocrystalline diamond and/or an amorphous carbon and/or a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, that is obtained from the process according to claim 1 or 20.

27. The nanocrystalline carbon with the ID, 2D, or 3D structure and/or the nanocrystalline diamond and/or the amorphous carbon and/or the metal-carbon nanomaterial composite, said composite containing the post-transition or the transition metal, according to claim 26, which comprises a graphitic carbon having an average crystallite domain size within a range of 1-100 nm.

28. A product that is a mixture having various carbon structures comprising: a nanocrystalline diamond, an amorphous carbon, a graphitic carbon, and a metal-carbon nanomaterial composite, said composite containing a post-transition or a transition metal, said product being obtained from the process according to claim 1 or 20.

29. The product according to claim 28 that comprises a graphitic carbon having an average crystallite domain size within a range of 1-100 nm.

30. The product according to claim 28, wherein the various carbon structures further comprise a graphite or a graphene.