Electrolysis is a concentrated process to decompose the chemical components of any solution. In this process, electrical energy works as a driving power to bring chemical changes. So, electrolysis of water means the decomposition of water. In the dissolution of water, the driving force, electrical energy splits Water into Hydrogen(H2) and Oxygen (O2).
Electrolysis of Water is a direct process to separate the elements of water through a non-spontaneous reaction. This reaction requires an electric current, which can pass through the water. And at the end of the process, pure Oxygen and Hydrogen gas become separated from the water.
In diverse industrial applications, electrolysis of water is an extensive and popular method in the power plants, food industries, this non-spontaneous chemical process yields efficient hydrogen and oxygen molecules. And these broken molecules of water provide required fuel sources in different applications.
General Facts on Electrolysis of Water
But remember, electrolysis of water is not an easy process of decomposition. It involves enormous factors. You can get some ideas and concepts on those factors from the relevant websites and portals. Now, the following points will hint why this reaction not so simple:
● The isolation of hydrogen and hydroxide ions from water is a very delicate process. In neutral water, the cluster of the atoms is equal. To flow the electrical energy, the entire process requires the charge carriers. So, low amounts of ions in water mean it’s a bad conductor of electrical energy. So, much purity is not a potential factor for electrolysis of water.
● The association of hydrogen ions with another element of water creates hydronium ions. The existence of hydronium ion prevents this non-spontaneous chemical process. Because, to yield oxygen gas, hydroxide ions need to reach the anode. And hydronium ion neutralizes the flow of hydroxide ions towards the anode. The same reason is responsible for neutralizing hydrogen near the cathode. Because hydroxyl ion exists near the cathode and prevents the flow of hydrogen, the splitting of Hydrogen and Oxygen from the water’s electrolysis will be minimal.
● Water electrolysis also needs the involvement of electron transfer. This chemical relocation will supply electrons to anode from anion and to cations from the cathode.
● Electrodes are another common molecule, which acts as static stable like platinum in the electrolysis of water. Similarly, an electrolyte is a kind of solute and exists in a solution. At the end of the reaction, it yields gas.
Considerable Factors to Ensure the Efficiency of Electrolysis of Water
The smooth electron transfer defines the efficiency of water electrolysis. Some chemical reactors can affect this transfer:
● The availability of potential anions and cations in the solution. Anions define charged negative ions and cations define charged positive ions. Due to the loss of electrons by metal and the gaining of those electrons by nonmetal these two charged ions form.
● The movement ratio of ions for reaching to the electrode.
● Availability of required activation power to ease the electron mobility to the electrolyte ions from the electrode.
● The potential effect of the gas, which exists as bubbles around the electrode.
● Availability of multiple interfaces such as solid-gas, solute-liquid, solute-solid. These potential interfaces play a vital role in yielding the required energy for the electrolysis of water.
How to Get Cell Potential in Electrolysis of Water?
❖ If you use pure water for electrolysis, the cell potential becomes negative. So, it is not a favorable option according to its thermodynamic feasibility. In pure water, low concentrated ions make a requirement of extra voltage to cross the interfaces by electrons. So, each electrode should be almost 0.6V.
❖ Generally, to continue the electrolysis with pure water, we need external energy of 2.4 v. So, to make possible the pure water electrolysis, you need to increase thermodynamic feasibility. It is only possible while the conductivity level increases. The availability of the number of potential ions can boost conductivity. Research is going on to enhance the conductivity in the electrolysis of water with non-reacting salts, acids, and bases.
Addition of Acid (Lower Than pH Level -7) in Electrolysis of Water
The presence of acid supplies additional hydrogen ions. At the cathode, this new H2 will be reduced, and at the anode, water will be oxidized. The addition of acid with a lower pH level creates a lower cell potential ratio than pure water for electrolysis.
Addition of Base ( Higher Than pH Level -7) in Electrolysis of Water
The added hydroxyl ions split the electrons to the anode. And the presence of particles near the cathode oxidizes the nearby water molecules. And the electrolysis in the primary medium yields the same results as the acid medium. It also works as a lower potential.
Addition of Salts For Electrolysis of Water
Salts hundred percent splits into the anions and cations in the water solution. So, it boosts the level of ionic concentration to increase the conductivity level. But the anions and cations, yielding from the salt, get attracted to the electrodes. Thus these charged ions compete with the decomposition reaction for generating O2 and H2. So, salts should be selected with essential non-competitor ions.
Here, one thing that can help you. The first and second groups of chemistry elements (K, Mg, Li, Na, Ca, Ba) have lower potential based ions than H2 ions. They do not decrease to split water into hydrogen.
In the comparison of hydroxide ions, non-reactive anions such as sulfate and nitrate ions have less potential for reduction. Sulfate oxidation
has the reduction levels of +2.1 V potential.
Besides, polymeric ionic, non-soluble compounds can help electrolysis of water with less cell potential than 1.5 V.
Different Kind of Electrolytes Participates in Electrolysis of Water
Electrolyzers For Electrolysis of Water – Polymer Electrolyte Membrane
This electrolyzer is based on PEM (Polymer electrolyte membrane).
The electrolyte acts as a super specialty plastic material. The following points describe reaction flow:
❖ At the anode, the reaction between water molecules and protons yields Oxygen.
❖ An external circuit carries the electrons and proton crosses the interface of PEM to reach the cathode.
❖ Electrons come from the external circuit and make a combination with protons at the cathode to yield hydrogen.
Electrolyzers For Electrolysis of Water – Alkaline
Alkaline electrolyzers run operation through the transporting the OH-. Electrolytes are the transporters of hydroxide ions to the anode from the cathode. At the moment, it generates hydrogen at the cathode portion. Liquid alkaline such as potassium or sodium is the driving solution, used by electrolyzers.
Electrolyzers For Electrolysis of Water – Solid Oxide
Solid Oxide electrolyzer, which completes the electrolysis process using the ceramic compound as electrolyte. This electrolyte acts as a conductor of (O2-). And at the standard temperature, it follows a different reaction process to yield hydrogen.
❖ The combination of water and electrons at cathode yields H2 and O2-. The external circuit allows electrons to flow to the cathode.
❖ Using the ceramic membrane’s interface, the oxygen ions pass for the reaction at the anode and yield oxygen gas. It also produces electrons
for external circuits.
Nowadays, energy storage is one of the essential purposes served by the electrolysis of water. Yielding hydrogen has different perceptions, such as fertilizer and biogas applications. Considering the high operation densities and astronomical scaleability cycles, PEM electrolyzers have high demand. This is an extensive and preferred technology for giant-scale energy storage.
So, all the discussed points will help to make the infrastructure of a profitable energy portfolio. For getting further ranges of required conditions to execute electrolysis of water, you can browse the WaterBug portal.