Zn phthalocyanine/carbon nitride heterojunction for visible light photoelectrocatalytic conversion of CO₂ to methanol

Zinc phthalocyanine/carbon nitride nanosheets photoelectrocatalysts were obtained by evaporation and calcination of the mixture of ZnPc and carbon nitride. It exhibits highly efficient synergistic function between PC-CO₂RR and EC-CO₂RR. The energy band matching between the ZnPc and carbon nitride results in the faster electrons transfer and less electron-hole pairs recombination. The optimized ZnPc/carbon nitride at a ratio of 0.1 wt% demonstrates high efficiency in photoelectrocalytic reduction of CO₂ under visible light, generating a major product of methanol at a yield of 13 μmol·cm⁻² after 8 h. The efficiency of photoelectrocalytic reduction of CO₂ to methanol is 2.6 times as high as that of electrocatalytic CO₂ reduction reaction, and 5.9 times as high as that of photocatalytic CO₂ reduction reaction. The mechanism of the photoelectrocatalytic CO₂ reduction reaction to methanol was discussed in detail.