Direct Z-Scheme Polymer/Polymer Double-Shell Hollow Nanostructures for Efficient NADH Regeneration and Biocatalytic Artificial Photosynthesis under Visible Light

Abstract

The design of a highly efficient polymer photocatalyst is an essential prerequisite for photo-biocatalysis in a polymer−enzyme coupled system, which offers an important platform for the synthesis of pharmaceuticals and fine chemicals. However, current polymers still suffer drawbacks of poor water wettability, low visible light absorption, and high recombination rate of photoinduced electron/hole pairs, which severely limit their application in photo-biocatalysis. Herein, we demonstrate a polymer/polymer double-shell hollow nanostructure (PCN@ PDBTS-HN) via a facile two-step polymerization with polymeric carbon nitride (PCN) and poly-dibenzothiophene sulfone (PDBTS) as internal and external shells, respectively. The covalent connection of those two polymer layers ensures the spontaneous electron transfer from PDBTS to PCN, as reflected in X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and fluorescence spectra, which could effectively accelerate the charge separation and migration. Thanks to its improved light-harvesting, increased hydrophilicity, and enhanced redox capacity, the obtained PCN@PDBTS-HN demonstrates an excellent catalytic efficiency in visible-light-promoted NADH regeneration with a conversion of 85.4% being achieved in 40 min (turnover frequency of 0.859 mmol g −1 h −1 ). This value is 1.4 and 2.6 times higher than that of pristine PCN and PDBTS, respectively, indicating an essential role of Z-scheme heterojunction in improving the catalytic efficiency. In addition, PCN@PDBTS-HN also displays excellent photocatalytic selectivity for 1,4-NADH regeneration, remarkable photostability, and good biocompatibility. A total amount of 2.12 mM methanol and 8.39 mM L-glutamate was accumulated in the polymer/alcohol dehydrogenase (YADH) and polymer/glutamate dehydrogenase (GDH) coupled system, respectively, implying high flexibility of fine chemical production via the photo-biocatalytic approach.

Triazine Frameworks for the Photocatalytic Selective Oxidation of Toluene

“…In the EIS spectra (Figure S23b), all polymers show semicircular plots which can be fitted by a Randles equivalent circuit (inset in Figure S23b), where R es , R ct and CPE are the electrolyte solution resistance, charge transfer resistance and constant phase element, respectively. [18] The matching values are given in Table S2. CTF-Th-0 has a R ct of 18.54 kohm, which is the lowest of all the polymers tested.…”

Heteroatom Structural Engineering of Conjugated Porous Polymers Enhances Photocatalytic Nicotinamide Cofactor Regeneration

“…The reasonable explanation is that under dark conditions, electrons are enriched on the electronegative sulfur and oxygen atoms, which leads to a stronger polarization distribution of electrons. When exposed to light, the electron‐rich sulfur and oxygen atoms are more likely to produce excited electrons than the neighboring C atoms, which facilitates faster charge separation and transfer [11c,22] …”

Recent advances in porous materials for photocatalytic NADH regeneration

“…The combination of Z-type structure and hollow morphology enabled PCN@PDBTS-HN to achieve an excellent 1,4-NADH regeneration yield of 85.4% within 40 minutes of light exposure. 94…”

“…The combination of Z-type structure and hollow morphology enabled PCN@PDBTS-HN to achieve an excellent 1,4-NADH regeneration yield of 85.4% within 40 minutes of light exposure. 94 Photocatalysts with high surface area, strong light trapping ability, and bionic internal structure were prepared by etching SiO 2 templates with different nanomorphologies, and their effects on reactivity were explored, which provided a new idea for rational design of efficient articial photosynthesis systems. Inspired by thylakoid lms with folded structures, Huang et al synthesized mesoporous spheres (CNMS) composed of graphitic carbon nitride nanosheets, as shown in Fig.…”