g-C3N4/MnFe2O4 p-n hollow stratified heterojunction to improve the photocatalytic CO2 reduction activity

Graphite carbon nitride (g-C3N4) is considered as a promising photocatalyst for CO2 reduction. However, they have problems such as small surface area and fast electron hole recombination rate, so how to improve the photocatalytic efficiency of g-C3N4 remains a great challenge. In this paper, g-C3N4/MnFe2O4 p-n heterojunction composites were synthesized successfully, and their photocatalytic activity for CO2 reduction was tested. We constructed g-C3N4 nanotubes to increase its specific surface area and increase the active sites available for reaction. The structure of p-n heterojunction promotes electron hole separation. The results indicate that under visible light irradiation, CO yield of g-C3N4/MnFe2O4 composite can reach 1136.8 μmol h−1 g−1 when the molar ratio of g-C3N4 microtubules to MnFe2O4 is 10:3, which is 14 times of g-C3N4 microtubules and 29 times of g-C3N4. This study provides some guidance for the design of g-C3N4 based heterojunction.