Gas-diffusion electrocrystallization

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Gas-diffusion electrocrystallization (GDEx) is an electrochemical process consisting on the reactive precipitation of metal ions in solution (or dispersion) with intermediaries produced by the electrochemical reduction of gases (such as oxygen), at gas diffusion electrodes. [1] [2] [3] It can serve for the recovery of metals or metalloids into solid precipitates [4] or for the synthesis of libraries of nanoparticles. [1]

Contents

History

The gas-diffusion electrocrystallization process was invented in 2014 by Xochitl Dominguez Benetton at the Flemish Institute for Technological Research, in Belgium. The patent for the process granted in Europe was filed in 2015 and its expiration is anticipated in 2036. [5]

Process

Gas-diffusion electrocrystallization is a process electrochemically driven at porous gas-diffusion electrodes, in which a triple phase boundary is established between a liquid solution, an oxidizing gas, and an electrically conducting electrode. The liquid solution containing dissolved metal ions (e.g., CuCl2, ZnCl2) flows through an electrochemical cell equipped with a gas diffusion electrode, making contact with its electrically conducting part (typially a porous layer). The oxidizing gas (e.g., pure O2, O2 in air, CO2, etc.) percolates through a hydrophobic layer on the gas diffusion electrode, acting as a cathode. After the gas diffuses to the electrically conducting layer acting as an electrocatalyst (e.g., hydrophilic activated carbon), the gas is electrochemically reduced. For instance, by imposing specific cathodic polarization conditions (e.g., −0.145 VSHE O2 is reduced, to H2O2 in a 2 electron (2 e–) transfer process and H2O in a 4 electron (4 e–) transfer process. OH– are also produced in the process. As this happens, abrupt local pH and local electrolyte redox potential changes arise within the cathode porosity. As the hydroxyl ions spread to the bulk electrolyte, systematic pH increases become consistently manifest in the electrolyte bulk. In due course, low amounts of H2O2 are generated. In steady state, a reaction front is fully developed throughout the hydrodynamic boundary layer. This creates local saturation conditions at the electrochemical interface, where metal ions precipitate in metastable or stable phases depending on the operational variables. When oxygen is the oxidizing gas, the mechanism for gas-diffusion electrocrystallization has been explained as an oxidation-assisted alkaline precipitation using gas-diffusion electrodes. [6]

Honors

In 2020, the gas-diffusion electrocrystallization process was presented as a great EU-funded innovation by the Innovation Radar of the European Commission, for its application on the secondary recovery of platinum group metals. [7]

Related Research Articles

Electrochemistry Branch of chemistry

Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electrical potential as an outcome of a particular chemical change, or vice versa. These reactions involve electrons moving between electrodes via an electronically-conducting phase, separated by an ionically-conducting and electronically insulating electrolyte.

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: elektron, meaning amber, and hodos, a way.

Electrochemical cell Device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions

An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells. A common example of a galvanic cell is a standard 1.5 volt cell meant for consumer use. A battery consists of one or more cells, connected in parallel, series or series-and-parallel pattern.

Electrolysis Technique in chemistry and manufacturing

In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity".

Lithium-ion battery Rechargeable battery type

A lithium-ion battery or Li-ion battery is a type of rechargeable battery. Lithium-ion batteries are commonly used for portable electronics and electric vehicles and are growing in popularity for military and aerospace applications. A prototype Li-ion battery was developed by Akira Yoshino in 1985, based on earlier research by John Goodenough, M. Stanley Whittingham, Rachid Yazami and Koichi Mizushima during the 1970s–1980s, and then a commercial Li-ion battery was developed by a Sony and Asahi Kasei team led by Yoshio Nishi in 1991.

Galvanic cell Assignment

A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous reactions. A common apparatus generally consists of two different metals, each immersed in separate beakers containing their respective metal ions in solution that are connected by a salt bridge.

Electrolytic cell Cell that uses electrical energy to drive a non-spontaneous redox reaction

An electrolytic cell is an electrochemical cell that uses electrical energy to drive a non-spontaneous redox reaction. It is often used to decompose chemical compounds, in a process called electrolysis—the Greek word lysis means to break up. Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, and bauxite into aluminium and other chemicals. Electroplating is done using an electrolytic cell. Electrolysis is a technique that uses a direct electric current (DC).

In electrochemistry, standard electrode potential (E°) is defined as The value of the standard emf of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode.

Proton-exchange membrane fuel cell

Proton-exchange membrane fuel cells (PEMFC), also known as polymer electrolyte membrane (PEM) fuel cells, are a type of fuel cell being developed mainly for transport applications, as well as for stationary fuel-cell applications and portable fuel-cell applications. Their distinguishing features include lower temperature/pressure ranges and a special proton-conducting polymer electrolyte membrane. PEMFCs generate electricity and operate on the opposite principle to PEM electrolysis, which consumes electricity. They are a leading candidate to replace the aging alkaline fuel-cell technology, which was used in the Space Shuttle.

Alkaline fuel cell

The alkaline fuel cell (AFC), also known as the Bacon fuel cell after its British inventor, Francis Thomas Bacon, is one of the most developed fuel cell technologies. Alkaline fuel cells consume hydrogen and pure oxygen, to produce potable water, heat, and electricity. They are among the most efficient fuel cells, having the potential to reach 70%.

Electrolysis of water Electricity-induced chemical reaction

Electrolysis of water is the process of using electricity to decompose water into oxygen and hydrogen gas by a process called electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, or remixed with the oxygen to create oxyhydrogen gas, which is used in welding and other applications.

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Nanobatteries Type of battery

Nanobatteries are fabricated batteries employing technology at the nanoscale, particles that measure less than 100 nanometers or 10−7 meters. These batteries may be nano in size or may use nanotechnology in a macro scale battery. Nanoscale batteries can be combined together to function as a macrobattery such as within a nanopore battery.

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Lithium-ion capacitor Hybrid type of capacitor

A lithium-ion capacitor (LIC) is a hybrid type of capacitor classified as a type of supercapacitor. It is called a hybrid because the anode is the same as those used in lithium-ion batteries and the cathode is the same as those used in supercapacitors. Activated carbon is typically used as the cathode. The anode of the LIC consists of carbon material which is often pre-doped with lithium ions. This pre-doping process lowers the potential of the anode and allows a relatively high output voltage compared to other supercapacitors.

Electrocatalyst

An electrocatalyst is a catalyst that participates in electrochemical reactions. Electrocatalysts are a specific form of catalysts that function at electrode surfaces or, most commonly, may be the electrode surface itself. An electrocatalyst can be heterogeneous such as a platinized electrode. Homogeneous electrocatalysts, which are soluble, assist in transferring electrons between the electrode and reactants, and/or facilitate an intermediate chemical transformation described by an overall half reaction. Major challenges in electrocatalysts focus on fuel cells.

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The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow.

Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and cost.

Xochitl Dominguez Benetton is a Mexican scientist, graduated as a Doctor of Science at the Mexican Petroleum Institute in 2008. She conducts research at the Flemish Institute for Technological Research since 2011.

References

  1. 1 2 Prato, Rafael; van Vught, Vincent; Chayambuka, Kudakwashe; Pozo, Guillermo; Eggermont, Sam; Fransaer, Jan; Dominguez-Benetton, Xochitl (2020). "Synthesis of material libraries using gas diffusion electrodes". Journal of Materials Chemistry A. 8: 11674–11686. doi: 10.1039/D0TA00633E .
  2. ↑ Prato, Rafael; van Vught, Vincent; Eggermont, Sam; Pozo, Guillermo; Marin, Pilar; Fransaer, Jan; Dominguez-Benetton, Xochitl (2019). "Gas Diffusion Electrodes on the Electrosynthesis of Controllable Iron Oxide Nanoparticles". Scientific Reports. 9: 15370. doi: 10.1038/s41598-019-51185-x .
  3. ↑ Pozo, Guillermo; de la Presa, Patricia; Prato, Rafael; Morales, Irene; Marin, Pilar; Fransaer, Jan; Dominguez-Benetton, Xochitl (2020). "Spin transition nanoparticles made electrochemically". Nanoscale. 12: 5412–5421. doi: 10.1039/C9NR09884D .
  4. ↑ Pozo, Guillermo; van Houtven, Diane; Fransaer, Jan; Dominguez-Benetton (2020). "Arsenic immobilization as crystalline scorodite by gas-diffusion electrocrystallization". Reaction Chemistry and Engineering. 5: 1118–1128. doi: 10.1039/D0RE00054J .
  5. ↑ ,"An electrochemical process for preparing a reaction product of a metal or metalloid element"
  6. ↑ Eggermont, Sam; Prato, Rafael; Dominguez-Benetton, Xochitl; Fransaer (2021). "Oxidation-assisted alkaline precipitation of nanoparticles using gas-diffusion electrodes". Reaction Chemistry and Engineering. Advance Article. doi: 10.1039/D0RE00463D .
  7. ↑ https://www.innoradar.eu/innovation/29828
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