The photocatalytic CO₂ reduction process uses solar energy to convert CO₂ and H₂O into fuel and high-value chemicals by simulating photosynthesis. The photocatalytic method is regarded as one of the most promising solutions to global energy and environmental problems due to its green and mild conditions ^{[1, 2]}.

There are many kinds of products involved in the photocatalytic CO₂ reduction reaction, and the different products produced by the reaction are caused by the different number of electrons required in the reaction process. Therefore, the calculation method of different yields in the photocatalytic CO₂ reduction reaction is closely related to the number of electrons transferred in the reaction process. Table of specific products and corresponding transfer electron number in photocatalytic CO₂ reduction reaction is sorted out, as shown in the following table:

Table 1. Photocatalytic reduction of CO₂ to various products and corresponding electrode equation ^[3].

The activity rating indexes involved in photocatalytic CO₂ reduction mainly include the following 6 kinds: 1. Reaction rate of target product of photocatalytic CO₂ reduction reaction (R product) ^[4] : the amount of target product produced by catalyst per unit mass in unit time, and the calculation formula is as follows: 

 n_产物: the amount of product substance (μmol); 

 R产物: reaction rate of target product (μmol·h^-1·g^-1); 

 M: mass of catalyst (g); 

 T: reaction time (h).

2. Electron consumption rate (R electron) of photocatalytic CO₂ reduction reaction ^[5] : the effective photogenic electron rate involved in the reaction, calculated by the following formula:

R_电子：Electron consumption rate（μmol·h^-1·g^-1）; 

R_产物：The reaction rate of the target product（μmol·h^-1·g^-1）; 

K₁、K₂、K₃：The number of transferred electrons corresponding to different products is shown in Table 1. 

3. Theoretical oxygen production of photocatalytic CO₂  reduction reaction ^[6] : According to the number of effective photogenerated electrons (holes) involved in the reaction, the content of O₂  that can be generated by the reaction is deduced.

理论产氧量单位：μmol； 

n_产物：The amount of substance in the target product（μmol）； 

K₁、K₂、K₃：The number of transferred electrons corresponding to different products is shown in Table 1.

R_产物：The reaction rate of the target product（μmol·h^-1·g^-1）; 

R_电子：Electron consumption rate（μmol·h^-1·g^-1）; 

K₁、K₂、K₃：The number of transferred electrons corresponding to different products is shown in Table 1. 

5. Apparent Quantum Yield (AQY) of photocatalytic CO₂ reduction reaction ^[4] : The ratio of the number of electrons transferred to the number of incident photons in the reaction system at a specific monochromatic wavelength.

Ne：Total number of reactive transferred electrons； 

n_产物：The amount of substance in the target product（μmol）； 

K₁、K₂、K₃：The number of transferred electrons corresponding to different products is shown in Table 1； 

Np：Number of incident photons. 

Click to view details“Quantum Yield (AQY) Calculation nanny tutorial, you deserve it!”。 

6. Solar to Chemical Energy Conversion Efficiency (STC) for photocatalytic CO² reduction ^[8] : The Efficiency of converting Solar Energy into Chemical Energy is calculated as follows:

R_产物：The reaction rate of the target product（mol·s^-1）; ∆Gr：Moles of gibbs free energy for the target reaction（J·mol^-1）; 

H₂O(l) →H₂(g) + 1/2O₂(g)           ∆Gr = 237 kJ·mol^{-1 [2]}； 

CO₂(g) → CO (g) + 1/2O₂(g)         ∆Gr = 257 kJ·mol^{-1 [2]}； 

CO₂(g) + 2H₂O(l) →CH₄ (g) + 2O₂(g)  ∆Gr = 890.9 kJ·mol^{-1 [2]}； 

Psun：AM 1.5G Optical power density of the standard solar spectrum（1000 W·m^-2）; 

S：Lighting area（m²）。

The above information is from the photocatalytic CO₂ reduction related research literature, the editor is only the information of the porter, if there is any error, also hope to point out in time!