What is a standard hydrogen electrode? How is it prepared? Explain with a labelled diagram?

The Standard Hydrogen Electrode (SHE) is a reference electrode used in electrochemical measurements to establish a standard reference potential of zero volts. It is essential in electrochemical cells for determining the electrode potential of other electrodes.

Preparation of Standard Hydrogen Electrode
Components:

Platinum Electrode: A platinum electrode is used because it is inert and provides a stable surface for the hydrogen gas to interact with.
Hydrogen Gas (H₂): The gas is purified and supplied at a pressure of 1 atmosphere.
Hydrochloric Acid (HCl): A solution of 1 M HCl is used to provide a consistent concentration of hydrogen ions.
Preparation Steps:

Platinum Electrode Preparation: Clean the platinum electrode to ensure it is free from contaminants.
Hydrogen Gas Supply: Pass hydrogen gas over the platinum electrode to ensure the gas bubbles over the surface.
Electrode Placement: The platinum electrode is immersed in 1 M HCl solution.
Gas Pressure: Maintain the hydrogen gas at a pressure of 1 atmosphere and a temperature of 298 K (25°C).
Equilibrium: Allow the system to reach equilibrium, where the hydrogen gas reacts with hydrogen ions in the solution to produce a standard reference potential.