Selective Photocatalytic Reduction of CO₂‐to‐CO in Water using a Polymeric Carbon Nitride Quantum Dot/Fe‐Porphyrin Hybrid Assembly

Abstract

Visible light-driven conversion of CO 2 into more value-added products is a promising technology not only for diminution of CO 2 emission but also for solar energy storage in the form of chemical energy. However, photocatalytic materials that can efficiently and selectively reduce CO 2 -to-CO in a fully aqueous solution typically involve precious metals that limit their suitability for large scale applications. Herein, a novel photocatalytic assembly is reported, consisting of polymeric carbon nitride quantum dots (CNQDs) as the visible light absorber and a Fe-porphyrin complex (Fe-p-TMA) as the catalyst for CO 2 -to-CO conversion. Both components were carefully selected to allow for excellent solubility in water as well as improved electronic communication through complementary electrostatic and π-π interactions. This CNQD • [Fe-p-TMA] hybrid assembly, at the optimized molar ratio, can produce CO with a turnover number (TON) exceeding 10 5 and selectivity ~96 % after 10 hours of visible light irradiation (400-700 nm). It is postulated that the enhanced CO 2 -to-CO transformation performance is due to the convenience of a more direct charge transfer (CT) pathway between the CNQDs and [Fe-p-TMA] motif.

Recent Progress in Porphyrin/g-C3N4 Composite Photocatalysts for Solar Energy Utilization and Conversion

“…As a result, the photocatalytic hydrogen production performance of 2%NP/g-C 3 N 4 surpassed that of ZnTCPP/g-C 3 N 4 and ZnTPP/g-C 3 N 4 . The Abrahamsson group [27] prepared a hybrid assembly of carbon nitride quantum dots (CNQDs) and Fe-porphyrin (Fe-p-TMA), where CNQDs functioned as a visible light absorber and Fe-p-TMA acted as the catalyst for CO 2 to CO conversion. The interactions between CNQDs and Fe-porphyrin involved electrostatic forces and π-π stacking, establishing a more direct charge transfer pathway that greatly facilitated the CO 2 to CO transformation.…”

“…The introduction of NP efficiently inhibited charge r nation and facilitated Förster energy transfer from the donor (g-C3N4) to the accep due to the overlap between the absorption spectrum of NP and the emission of g-C a result, the photocatalytic hydrogen production performance of 2%NP/g-C3N4 su that of ZnTCPP/g-C3N4 and ZnTPP/g-C3N4. The Abrahamsson group [27] prepar brid assembly of carbon nitride quantum dots (CNQDs) and Fe-porphyrin (Fe-p where CNQDs functioned as a visible light absorber and Fe-p-TMA acted as the for CO2 to CO conversion. The interactions between CNQDs and Fe-porphyrin i electrostatic forces and π-π stacking, establishing a more direct charge transfer p that greatly facilitated the CO2 to CO transformation.…”