Tri-phase photocatalysis for CO2 reduction and N2 fixation with efficient electron transfer on a hydrophilic surface of transition-metal-doped MIL-88A (Fe)

Efficient transfer of charges at the interface of transition-metal and semiconductor can improve efficiency of photocatalyst. Herein, we examined photoactivity of Mn and Zn-doped MIL-88A for CO2 reduction and N2 fixation by water under UV-vis irradiation and ambient conditions. Gaseous-phase photo-reduction of CO2 generated CO, H2, and CH4. Apparent quantum yield of Zn-MIL-88A was found to be 2.16-folds higher than that of pristine MIL-88A catalyst. Also, the highest NH4+ generation rate (300 mu molg- 1h- 1) was for Zn-MIL-88A catalyst. Dissecting the underlying mechanism discloses that electrons efficiently transferred from doped transition-metals to the Fe-O cluster of MIL-88A. The hydrophilic surface of the tested catalysts in a tri-phase photocatalyst system led the process to be controlled by mass-transport; which governed the product distribution and limited the kinetics of the process. Experimental results also unveil that the addition of transition metals improved stability, charge-separation, and efficiency of the resulting photocatalysts.

Automated summary

Efficient charge transfer at the interface of transition-metal and semiconductor can enhance the efficiency of photocatalysts. The study showed that Zn-doped MIL-88A exhibited higher photoactivity for CO2 reduction and N2 fixation compared to pristine MIL-88A, with increased apparent quantum yield and NH4+ generation rate. Additionally, the addition of transition metals improved stability, charge-separation, and efficiency of the resulting photocatalysts.