Dual role of g-C3N4 microtubes in enhancing photocatalytic CO2 reduction of Co3O4 nanoparticles

The activity of photocatalytic CO 2 reduction (PCR) remains inadequate due to the thermodynamically stable CO 2 molecules and sluggish carrier kinetics. This work simultaneously adopts active site and heterojunction engineering to collaboratively enhance PCR. A heterojunction of g-C 3 N 4 microtube-supported Co 3 O 4 nanoparticle has been developed through the hydrothermal pretreatment and calcination processes. The g-C 3 N 4 microtubes play dual roles in enhancing PCR of Co 3 O 4 : (1) they act as a substrate to support Co 3 O 4 nanoparticles, thereby making small size and good dispersion of Co 3 O 4 nanoparticles. The Co active sites can be highly exposed to accept photogenerated electrons and capture CO 2 molecules; and (2) the p-type Co 3 O 4 nanoparticles and n-type g-C 3 N 4 microtubes build a p–n junction. An internal electric field is created to expedite the charge transfer. As a result, the g-C 3 N 4 microtube-supported Co 3 O 4 nanoparticle affords a significantly high turnover number (TON) of 24.72, which is 24-fold higher than that of the pure Co 3 O 4 and comparable to state-of-the-art photocatalysts .