A research team investigated the photoelectrochemical (PEC) water-splitting efficiency of … — ACT

A research team investigated the photoelectrochemical (PEC) water-splitting efficiency of a bismuth vanadate ( $BiVO_4$ ) photoanode. The experimental apparatus consisted of a three-electrode PEC cell connected to a potentiostat. The working electrode (photoanode) was illuminated by a simulated solar light source equipped with an Air Mass (AM) 1.5G filter and a water-filled optical filter. The electrochemical cell contained a $0.5\text{ M } Na_2SO_4$ aqueous electrolyte. A platinum ( $Pt$ ) wire counter electrode was used to complete the circuit, and a silver/silver chloride ( $Ag/AgCl$ ) electrode served as the reference. The gaseous products evolved at the electrodes were swept by an inert carrier gas into a gas chromatograph for quantification.

Match each component of the experimental apparatus to its primary function in this experimental setup.

Water-filled optical filterAbsorbs infrared radiation from the light source to prevent temperature-induced changes in electrolyte conductivity and reaction kinetics.
Platinum counter electrodeServes as the site for the complementary reduction reaction and allows charge transfer back into the electrolyte to maintain current flow.
Silver/silver chloride electrodeProvides a constant, known half-cell potential to enable precise regulation and monitoring of the photoanode's electrical state.
PotentiostatRegulates the voltage difference between the working and reference electrodes while recording the flow of charge through the system.

Answer

The water-filled optical filter matches with absorbing infrared radiation to prevent temperature-induced changes. The platinum counter electrode matches with serving as the site for the complementary reduction reaction. The silver/silver chloride electrode matches with providing a constant, known half-cell potential. The potentiostat matches with regulating the voltage difference while recording the flow of charge.

Each component is correctly matched based on the principles of three-electrode photoelectrochemical cells and optical solar simulation. The water-filled filter absorbs heat-generating infrared light to maintain temperature stability. The silver/silver chloride electrode provides a stable potential reference. The platinum counter electrode completes the circuit and hosts the reduction reaction. The potentiostat manages and measures the electrical potentials and current of the cell.

Step-by-Step Solution

Analyze the role of the optical water filter.

Water absorbs light strongly in the infrared region. Removing infrared wavelengths from the simulated solar light prevents the electrolyte from heating up during the experiment, maintaining a constant temperature and stable ionic conductivity.

This is crucial for isolating photoelectrochemical effects from thermal effects.

Analyze the role of the silver/silver chloride (

Ag/AgCl

) electrode.

In a three-electrode setup, the reference electrode must maintain a stable half-cell potential. The reference electrode serves as a stable reference point against which the working electrode potential is measured and controlled.

This prevents potential drift and ensures precise electrochemical measurements.

Analyze the role of the platinum counter electrode.

To avoid current passing through the reference electrode (which would alter its potential), a counter electrode is introduced. The platinum counter electrode completes the electrical circuit and provides the surface for the complementary reduction reaction (hydrogen evolution).

This maintains charge neutrality in the electrolyte and allows the photoanode current to flow.

Analyze the role of the potentiostat.

The potentiostat is the control instrument that maintains the potential of the working electrode at a constant level relative to the reference electrode by adjusting the current at the counter electrode.

This allows for precise control of the electrochemical driving force and measurement of the resulting photocurrent.

Key Concept

Function and operation of components in a three-electrode photoelectrochemical cell and optical filters in solar simulation.

Estimated Time:3m 0s

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