Reversible Hydrogen Electrode

Hydrogen-coupled reference for realistic electrochemical environments

The reversible hydrogen electrode (RHE) is a hydrogen-coupled reference electrode that defines potential via the hydrogen redox couple, 2H⁺ + 2e⁻ ⇌ H₂, directly in the electrolyte of interest. Because the potential shifts with solution pH, the RHE provides a physically meaningful reference scale for proton-coupled processes such as hydrogen evolution, oxygen evolution, fuel-cell electrocatalysis, corrosion and photoelectrochemistry.

Principle of operation and design

High-purity hydrogen gas is supplied to a platinised platinum electrode with a high real surface area, ensuring fast hydrogen adsorption–desorption kinetics and rapid equilibration between dissolved and gaseous hydrogen. A robust glass body with gas inlet, internal electrolyte and a low-leakage salt-bridge junction provides a stable and reproducible reference potential while minimising contamination of the working electrolyte. When mounted in a dedicated housing or double-junction reference cell, the RHE can be used across acidic, neutral and mildly alkaline media.

Typical design features include:

• Platinised Pt sensing element for fast, near-Nernstian response
• Dedicated H₂ inlet for continuous gas flow or static headspace operation
• Low-leakage junction for reduced drift and junction potentials
• Compatibility with standard 6–12 mm reference ports in common electrochemical cells
  
  

RHE vs SHE

The standard hydrogen electrode (SHE) is defined at unit hydrogen ion activity (approximately pH 0) and 1 bar H₂, with its potential fixed at 0.000 V by convention. The RHE uses the same hydrogen couple but equilibrates directly in the electrolyte under study, so its potential follows E_RHE ≈ E_SHE + 0.059 × pH at 25 °C. This makes the RHE a more convenient, experiment-specific reference for practical electrocatalysis, electrolyser and battery research.

Applications, compatibility and ScienceGears support

The RHE is ideal for benchmarking HER/OER catalysts, water electrolysis and fuel-cell studies, CO₂ reduction, corrosion, batteries and photoelectrochemical devices. It integrates seamlessly with potentiostats/galvanostats, rotating (ring-)disk electrodes, spectroelectrochemical cells and solar fuels workstations. ScienceGears supplies high-quality reversible hydrogen electrodes together with compatible electrochemical cells, potentiostats, CIMPS photoelectrochemical systems, Raman-SEC cells and battery cyclers, backed by local scientific support across Australia and New Zealand.