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A potentiostat is an electrochemical instrument that controls the potential difference (voltage) between the working electrode and the reference electrode while measuring the resulting current flow between the working and counter electrodes. It maintains a constant potential, making it ideal for studying redox reactions, corrosion, and processes where precise potential control is critical.

A galvanostat, on the other hand, controls the cell current rather than the voltage. This makes it suitable for applications where maintaining a constant current is required, such as electrolysis, electrodeposition, or battery charge-discharge testing.

All Metrohm Autolab and Metrohm Dropsens instruments combine both potentiostatic and galvanostatic capabilities in a single device, allowing users to select the most suitable mode based on their experimental needs.

Application Note: Basic overview of the working principle of a potentiostat/galvanostat (PGSTAT) – electrochemical cell setup

Blog: Fast and fundamental – Influences on reliable electrochemical measurements

Consider the following criteria to select a suitable potentiostat:

1. Voltage and current range
2. Workload
3. Portability
4. Hyphenation or all-in-one solution

Voltage and current range

Consider the range of potentials and currents you expect to work with.

• Basic requirement: Compliance voltage up to ± 10 V, max. current up to ± 100 mA: PGSTAT101, Autolab IMP, μStat-i 400 – Small, lightweight, and affordable
• Moderate requirement: Compliance voltage ± 20 V, max. current ± 400 mA: PGSTAT204 – Small and able to add one more module (e.g. EIS)
• Advanced requirement: Compliance voltage ± 30 V, max. current ±2 A (upgradeable) : PGSTAT302N – Customizable with a range of modules
• Stringent requirement: Compliance voltage ± 50 V, max. current ± 6 A: VIONIC powered by INTELLO – Highest specification and multi-modules in one instrument

Workload

If you plan to run multiple experiments simultaneously, you might need a potentiostat with multiple channels.

Go to Mulitchannel Line

Go to Portable Multichannel Line

Portability

A portable potentiostat can be beneficial in various scenarios where mobility, fieldwork, or on-site measurements are necessary. Metrohm can provide both single-channel and multi-channel portable potentiostats.

Go to Portable Singlechannel Line

Go to Portable Multichannel Line

Hyphenated Electrochemistry with third-party instruments or Spectroelectrochemistry integrated into one instrument

In a potentiostat, the grounded mode is used when none of the electrodes nor the cell vessel have a direct connection with the ground. This is the most commonly used mode for electrochemical experiments performed in laboratories (i.e., wet electrochemistry research, battery research, corrosion test in lab, etc.). If other devices are used during the electrochemical experiments, you can use the faraday cage to ground them.

The floating mode must be used in the following three main cases:

1. When the working electrode is directly connected to the Earth ground (grounded WE): Corrosion tests in open air, hydrogen permeation, in-situ electronic microscopy
2. When the counter electrode is directly connected to the Earth ground (grounded CE): Bioreactors, autoclave
3. When the entire cell is directly connected to the Earth ground (grounded Cell): Tribocorrosion, autoclave

For any of the above-mentioned cases, the correct measurement of the current is only possible if the potentiostat is used with the correct floating mode.

Selectable floating refers to the feature of potentiostats/galvanostats to choose the ground state of the cell setup. Due to the wide variation of experimental requirements and kinds of electrochemical cells, the use of an electrochemical instrument with a floating feature (such as VIONIC or µStat-i multiX among others) brings additional versatility to the user.

To perform an electrochemical hydrodynamic measurement and induce controlled hydrodynamic flow or convection, you need:

• Apparatus such as a rotating disk electrode (RDE) or a rotating ring-disk electrode (RRDE), which rotates the electrode at a stable speed to enhance mass transfer
• A potentiostat equipped with software that can control the RDE or RRDE

At Metrohm, we offer different models of potentiostats that can be used with our RDEs and RRDEs through dedicated software.

To simulate turbulent pipe-flow conditions in the lab for electrochemical corrosion research, the most common and practical approach is to use a Rotating Cylinder Electrode (RCE). The RCE setup recreates realistic turbulent flow conditions found inside pipes by rotating the electrode, which enhances mass transport and mimics the turbulent fluid flow experienced in real pipelines.

In addition, a potentiostat with dedicated software capable of controlling the rotating speed of the RCE is also essential.

White Paper: Corrosion Best Practice – Creating Pipe-flow Conditions Using a Rotating Cylinder Electrode

Yes, it is possible to perform electrochemical measurements with two or more working electrodes in the same cell. You can choose among different experimental setups based on your research needs.

If your research involves working with a Rotating Ring-Disk Electrode (RRDE) or a single screen-printed electrode that integrates two working electrodes, you will need a Bipotentiostat. At Metrohm, we offer different potentiostat models with Bipotentiostat functionality, such as the AUT302N and PGSTAT204 or portable models such as STAT-I-400.

If your research requires more than two working electrodes in the same electrochemical cell, other solutions are available:

• Potentiostat with multiBA: for simultaneous measurements on up to six working electrodes or STAT-I MULTI16 for simultaneous measurements up to 16 working electrodes.
• Potentiostat with Multiplexer Module (MUX-SCNR16): for sequential measurements on up to 128 working electrodes

To analyze EIS results, specialized software with data fitting tools is typically required. This process involves constructing an equivalent circuit in a flexible manner and fitting the calculated equivalent data to the measured results. Through this fitting process, the software determines and displays the quantitative values of each element in the circuit, allowing for a clear interpretation of the system’s electrochemical behavior.

At Metrohm, our potentiostat software, INTELLO, NOVA, and DropView 8400, provide all these features to ensure precise and reliable EIS data analysis.