Porphyrin Supramolecular Nanoassembly/C₃N₄ Nanosheet S-Scheme Heterojunctions for Selective Photocatalytic CO₂ Reduction toward CO

Abstract

The photocatalytic reduction of CO2 with H2O into valuable chemicals is a sustainable carbon-neutral technology for renewable energy; however, the photocatalytic activity and product selectivity remain challenging. Herein, an S-scheme heterojunction photocatalyst with superior CO2 photoreduction performanceporous C3N4 (CN) nanosheets anchored with zinc­(II) tetra­(4-cyanophenyl)­porphyrin (ZnTP) nanoassemblies (denoted as ZnTP/CN)was designed and prepared via a simple self-assembly process. The constructed ZnTP/CN heterojunction had rich accessible active sites, improved CO2 absorption capacity, and high charge carrier separation efficiency caused by the S-scheme heterojunction. As a result, the obtained ZnTP/CN catalyst exhibited considerable activity for photocatalytic CO2 reduction, yielding CO with a generation rate of 19.4 μmol g–1·h–1 and a high selectivity of 95.8%, which is much higher than that of pristine CN nanosheets (4.53 μmol g–1·h–1, 57.4%). In addition, theoretical calculations and in situ Fourier transform infrared spectra demonstrated that the Zn sites in the porphyrin unit favor CO2 activation and *COOH formation as well as CO desorption, thereby affording a high CO selectivity. This work provides insight into the design and fabrication of efficient S-scheme heterostructure photocatalysts for solar energy storage.

Ionic Liquid Modified Fe-Porphyrinic Metal–Organic Frameworks as Efficient and Selective Photocatalysts for CO2 Reduction

“…Based on the Mott–Schottky curves, it can be inferred that MOF-526 and IL x @MOF-526 series were n-type semiconductors due to the positive slopes of the linear plots (Figures S11–S14). , The flat band ( E fb ) potentials of IL100@MOF-526, IL200@MOF-526, IL400@MOF-526, and MOF-526 were measured with values of −0.96, −0.85, −0.89, and −0.91 V vs. SHE, respectively. The conduction band (CB) of the n-type semiconductor is approximately 0.2 V above E fb ; therefore, the CB of IL100@MOF-526, IL200@MOF-526, IL400@MOF-526, and MOF-526 were −1.16, −1.05, −1.09, and −1.11 V vs. SHE, respectively.…”

S-Scheme Heterojunction Based on Resorcinol–Formaldehyde Resin Nanosheets and Bi-Based Metal–Organic Frameworks for Efficient Photocatalytic H2O2 Production

“…This peak is believed to result from the π-stacking formed between adjacent D−A units. 26,33 The diffraction peaks of RF/Bi/B-0.3 at 10.6°, 12.8°, 22.2°, and 33.4°can be assigned to Bi-MOF. No distinct signal of RF is detected in the diffraction peaks of RF/Bi/B-0.3, which is attributed to the amorphous nature of the π-stacked donor−acceptor (D−A) pairs in RF.…”

“…24,25 The unique structure of Bi-MOF can offer rationality for designing Bi-MOF-containing donor−acceptor (D-A) photocatalysts. 26 Therefore, introducing new donor molecules to regulate the band construction of Bi-MOF is a promising approach to improve the H 2 O 2 production capacity of Bi-MOF. Resorcinol− formaldehyde resins (RF), a type of metal-free cross-linked polymer, have long been utilized as industrial raw materials.…”

When porphyrins meet 2D materials: spectroscopic and photocatalytic properties

“…By applying theoretical calculations and in situ Fourier transform infrared spectra, the authors suggested that the zinc sites in the porphyrin facilitate CO 2 activation and CO production. 174…”