Construction of α-Fe₂O₃/Sulfur-Doped Polyimide Direct Z-Scheme Photocatalyst with Enhanced Solar Light Photocatalytic Activity

Abstract

A novel two-dimensional α-Fe 2 O 3 /sulfur-doped polyimide (FO/SPI) direct Z-scheme photocatalyst was successfully constructed by a facile thermal treatment method. The effects of α-Fe 2 O 3 nanosheets on the morphology, chemical structure, and photoelectronic properties of FO/SPI composites were systematically characterized by different spectroscopic means. These methods include X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, transient fluorescence spectra, and so forth. It was confirmed that the small amounts of α-Fe 2 O 3 can availably facilitate exfoliation of bulk SPI, resulting in a transformation of SPI from bulk to 2D layered composite that illustrates tight interface through the coordination Fe–N bond and an all-solid-state direct Z-scheme junction. Thus, the transfer and separation efficiency of photogenerated electron/hole pairs were significantly enhanced, which greatly promoted improvement of the photocatalytic activity of the FO/SPI composite for methyl orange degradation under solar light. This work provides a new approach to constructing efficient inorganic–organic Z-scheme photocatalyst based on strong interface interaction.

Controllable Preparation of Highly Crystalline Sulfur-Doped Π-Conjugated Polyimide Hollow Nanoshell for Enhanced Photocatalytic Performance

“…Figure 2 shows the scanning electron microscope (SEM) images of BSPI and different addition ratios resulting in different thicknesses of HSPI. As shown in Figure 2 a, the BSPI is heavily agglomerated and shows a clear blocky accumulation form [ 11 ]. It is well known that the thickness of the shell layer of HSPI gradually becomes less as the proportion of silica template precursors increases ( Figure 2 b–f).…”

“…From Figure 5 c, three N 1s characteristic peaks of BSPI can also be observed at 397.3, 398.3, and 399.6 eV. The peak at 397.3 eV is from a pyridine-like nitrogen atom (N–C=N), and the two peaks at 398.3 and 399.6 eV can be attributed to the nitrogen atom attached to the two carbonyl groups (C = O) groups [ 11 ]. Additionally, the HSPI-3 samples all show a slight increase in the binding energy about N 1s with 397.7, 398.6, and 399.95 eV, respectively.…”

“…The synthesis of sulfur-doped polyimide was based on that reported by Ma et al [ 11 ]. Specifically, a certain amount of melamine, homothallic anhydride, and sublimated sulfur was weighed and dispersed in an aqueous ethanol solution after thorough grinding of the three, loaded into an inclined four-necked flask for vacuum stirring, and then centrifuged and dried to obtain a solid, which was heated from room temperature to 325 °C at a heating rate of 7 K/min, and the BSPI was obtained after maintaining this heating temperature for 4 h.…”

“…For this cause, Wang et al modified polyimide with sulfur by element doping to improve its photocatalytic activity [ 10 ]. However, the bulk SPI (BSPI) with irregular block layer structure prepared by the conventional method still has some drawbacks, such as small specific surface area and low pore capacity, leading to finite reaction sites, and its photocatalytic activity needs to be further improved [ 11 ].…”

Band structure engineering of a polyimide photocatalyst towards enhanced water splitting

“…To increase the photocatalytic efficiency, a number of different approaches have been investigated to date, such as doping, 32–34 co-monomer tuning, 35–39 morphology engineering, 40–42 and composite structure design. 43–49…”