Photodecomposition of Anode/Cathode

[citw]

Can some one explain (to a non-chemist) what exactly is happening in the decomposition reactions

[tex]
\text{MX}+zh^++\text{solv}\longrightarrow\text{M}^{z+}\cdot\text{solv}+\text{X}\text{ (oxidation) }
[/tex]

and

[tex]
\text{MX}+ze^-+\text{solv}\longrightarrow\text{M}+\text{X}^{z-}\cdot\text{solv} \text{ (reduction) }
[/tex]

In these reactions, MX referers to a compound semiconductor (e.g., M= Zn, Ga, Ti, etc., X=S, N, O₂, etc.). It's my understanding that the first equation describes the oxidation of the semiconductor by its photogenerated holes, while the second describes the reduction by photogenerated electrons. This can be found in the following article

http://pubs.acs.org/doi/abs/10.1021/cm302533s

However, as I have limited education in chemistry, I don't really understand what is meant by the terms such as z in front of the electron, or "solv" indicated with the oxidized/reduced products. Are we saying "z electrons/holes", therefore changing the oxidation state by this amount? The "solv" part I really don't know about.

 

[Borek]

z is just a small integer number, solv means solvent/solvated.

 

[citw]

z is just a small integer number, solv means solvent/solvated.

So is it like I was saying, "z" electrons/holes?

What does it mean that "solv" appears as an individual reactant but is indicated next to (as?) one of the products?

 

[Borek]

So is it like I was saying, "z" electrons/holes?

Yes.

What does it mean that "solv" appears as an individual reactant but is indicated next to (as?) one of the products?

The way I read it you don't know how many molecules of solvent are used to solvate the ion, and it is not that important. What is important is that the reaction takes place in solvent and its molecules do solvate the produced ion.

It is not a standard notation, just a handy shortcut.

 

[LudusRex]

In simple terms, the photodecomposition of anode/cathode refers to the breakdown of a compound semiconductor (MX) into its constituent parts, M and X, through the use of light energy. This process involves the transfer of electrons (e^-) and holes (h^+) between the anode and cathode.

In the first equation, the compound semiconductor is oxidized by the photogenerated holes, which means that the holes remove electrons from the semiconductor, resulting in the formation of a positively charged M ion and a negatively charged X ion. The "z" in front of the h^+ refers to the number of electrons that are removed from the semiconductor.

In the second equation, the compound semiconductor is reduced by the photogenerated electrons, which means that the electrons are added back to the semiconductor, resulting in the formation of a neutral M atom and a negatively charged X ion. The "z" in front of the e^- refers to the number of electrons that are added to the semiconductor.

The "solv" in both equations refers to the solvent, which is the substance that the compound semiconductor is dissolved in. This is important because the solvent can affect the rate of the decomposition reactions.

Overall, the photodecomposition of anode/cathode involves the transfer of electrons and holes between the anode and cathode, resulting in the breakdown of the compound semiconductor into its constituent parts.