A Study Of Photoelectric Synergy Reduction Of CO₂ Based On MePc/g-C₃N₄ NSs

Combustion of fossil fuel releasing large amounts of CO₂, Which triggered a host of environmental issues and took the attention of international communites to achieve renewable carbon resource. Electrocatalytic（EC） and photocatalytic（PC） reduction have good and bad points on CO₂ reduction. Photoelectrocatalytic（PEC） method could efficiently govern the advantages in the two aspects of PC and EC, simultaneously. So PEC is becoming an important research hotspot to achieve high efficiency and selectivity of CO₂ catalytic reduction.G-C₃N₄ is a non-metallic semiconductor, which has become one of the hot spots in the field of photocatalysis research because of the following aspects: low prices; suitable energy gap, etc. To further promote absorption of visible light and reduce electron-hole recombination rate, we choose metal phthalocyanines as photosensitive material to combine with g-C₃N₄. According to the locations of the conduction and valence band, cobalt phthalocyanine was decided to be the complexing agent. On the other hand, zinc phthalocyanine became the other alternative as for the photosensitivity and conductivity.Both of the two complexing agents achieved a decrease in the band gap, to different degrees, resulting in blue shift of the minimum absorption wavelength. which resulted a stronger response to the visible light. In the g-C₃N₄ /CoPc respect,the optimal proportion of g-C₃N₄ /CoPc is 0.1%; the energy gap narrowed 0.35 eV; the photoelectric conversion efficiencies achieve 69%. What’s more,the main deoxidized product of g-C₃N₄/CoPc is CH3 OH, which achieved 430 umol·L-1·cm-2. In the g-C₃N₄ /ZnPc respect, the optimal proportion of g-C₃N₄ /ZnPc is 0.1%;the energy gap narrowed 0.17 eV;the photoelectric conversion efficiencies achieve 47.9% and the main deoxidized product of g-C₃N₄ /ZnPc is CH₃OH, which achieved 325 umol·L-1·cm-2. Both the two different phthalocyanine compounds gave rise to a growth in the yield of CH3 OH detected by gas chromatography,compared with single g-C₃N₄. In terms of the production of CH3 OH, neither single PC nor single PE was superior to PEC. In conclusion, our experiment achieved the desired results.