Photoelectrochemical Cell: Can they work with external potential?

In summary, a photoelectrochemical cell with a photoanode (TiO2) and a metal counter electrode (Pt) can generate a photocurrent under UV illumination. This photocurrent can be increased with an external bias, but no photocurrent will be observed without UV illumination and no external bias. However, a current can still be produced with an external bias, but it would not be considered a photocurrent since it is not caused by external radiation on the cell.
  • #1
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Photoelectrochemical Cell for water splitting with semi conducting photoanode (TiO2) and metal counter electrode (Pt).

A photoelectrochemical cell under UV illumination generates a photocurrent. This photocurrent can be increased by applying an external bias because of improved exciton splitting.

No photocurrent is observed if there is no UV illumination and no external bias.

My question is: Can a photocurrent be generated with an external bias and no UV illumination?

Thanks
 
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  • #2
By definition: Photocurrent is the electric current through a photosensitive device, such as a photodiode, as the result of exposure to radiant power.

Therefore, if there is no radiation on the cell, then no photocurrent will be produced. If you apply a potential across the cell, you will see a current generated since any electrode can split water as long as it is given enough energy. This current would not be classified as a photocurrent since it is not caused by external radiation on the cell.

To summarize, a current can be produced by an external potential, but it will not be classified as a photocurrent unless there is illumination of the cell.
 

1. How does a photoelectrochemical cell work with external potential?

A photoelectrochemical cell is a type of solar cell that converts light energy into electrical energy. When light hits the semiconductor material of the cell, it generates electron-hole pairs, which then undergo a redox reaction at the interface of the electrode and electrolyte. This creates an electric potential, which can be harnessed as electrical energy.

2. What is the role of an external potential in a photoelectrochemical cell?

The external potential in a photoelectrochemical cell acts as an external bias that helps to drive the redox reactions and facilitate the flow of electrons. This is especially important for photoelectrochemical cells that use non-conductive electrolytes, as the external potential helps to overcome the resistance of the electrolyte and improve the efficiency of the cell.

3. Can photoelectrochemical cells operate without an external potential?

Yes, photoelectrochemical cells can operate without an external potential, but their efficiency may be lower. The external potential helps to improve the efficiency of the cell by providing an additional driving force for the redox reactions. However, some photoelectrochemical cells, such as dye-sensitized solar cells, do not require an external potential as they have a conductive electrolyte.

4. How does the external potential affect the performance of a photoelectrochemical cell?

The external potential has a significant impact on the performance of a photoelectrochemical cell. It can affect the rate of the redox reactions, the efficiency of electron transfer, and the overall output of the cell. An optimal external potential is needed to balance the competing reactions in the cell and maximize its efficiency.

5. Are there any limitations to using external potential in photoelectrochemical cells?

Yes, there are a few limitations to using external potential in photoelectrochemical cells. One limitation is that the external potential can cause corrosion of the electrodes, which can decrease the lifespan of the cell. Additionally, the external potential may also increase the cost and complexity of the cell, making it less practical for large-scale applications.

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