S‑scheme heterojunction of thin-layer O-modified graphitic carbon nitride/cobalt porphyrin to promote photocatalytic CO2 conversion

A S-Scheme heterojunction with close contact between CN and CoTPP was establish by a unique synthesis method. Formation of S-type heterojunction facilitated the efficient separation of photogenerated carriers and improved photocatalytic activity. [Display omitted] •The g-C3N4 is rapidly synthesized by the technology of thermal polycondensation.•Co-porphyrins is introduced to increase the catalytic activity of the catalyst.•Adjusting the ratio of loads can regulate the activity of CO2 reduction.•S-scheme heterojunction promotes efficient separation of photogenerated carriers. The emissions of CO2 are increasing year by year, which have led to serious environmental problems. Converting CO2 into valuable fuels through photocatalysis is a promising strategy. In this research, oxygen atoms were successfully innovated into graphitic carbon nitride (CN). Additionally, cobalt porphyrin (CoTPP) was successfully loaded onto the modified carbon nitride (Co/CN). The generation of interfacial electric fields and bending bands between CN and CoTPP was demonstrated experimentally. The electrons in the CN and the holes in the CoTPP were combined to form a unique S-scheme heterojunction structure, and efficient separation of carriers was promoted. As a result, the CO conversion under visible light irradiation reached an impressive 100.70 μmol g−1 h−1. By integrating theoretical and experimental findings, this study underscores the critical role of catalyst design in enabling efficient photocatalytic CO2 reduction.