Two‐step calcination synthesis of Z‐scheme α‐Fe₂O₃/few‐layer g‐C₃N₄ composite with enhanced hydrogen production and photodegradation under visible light

Abstract

Solar photocatalytic technology is of great significance for adjusting energy structure and environmental improvement. Developing an efficient and lowcost photocatalyst is key to realizing the conversion of solar to chemical energy. In this study, α-Fe 2 O 3-modified few-layer g-C 3 N 4 hybrids (α-Fe 2 O 3 /FL g-C 3 N 4) were successfully prepared by a two-step calcination route with a mixture of α-Fe 2 O 3 and melamine. The samples were characterized by Thermogravimetric analysis, X-ray diffraction, Fourier transform infrared, scanning electron microscope, transmission electron microscope, High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller, UV-Vis absorption spectrum, photoluminescence, and Timeresolved photoluminescence spectroscopy; furthermore, their photoelectrochemical measurements and their photocatalytic performances were evaluated by visible light-driven hydrogen evolution and degradation of RhB. The results showed that the hydrogen production activity and degradation ability of α-Fe 2 O 3 /FL g-C 3 N 4 were significantly enhanced compared with those of α-Fe 2 O 3 /multilayer g-C 3 N 4 (α-Fe 2 O 3 /ML g-C 3 N 4) and FL g-C 3 N 4. The enhanced photoactivities were mainly attributed to the synergistic effect between the increased visible-light absorption, enhanced surface area, and highly efficient electron transfer and separation on the Z-type heterojunction interface. This work not only provides evidence for the formation of FL g-C 3 N 4 nanosheets using a thermal exfoliation method but also provides new insights into the interfacial charge carrier dynamics of Z-scheme α-Fe 2 O 3 /FL g-C 3 N 4 heterostructures for photocatalytic H 2 generation and pollutant degradation.

Enhanced photoelectrochemical performance of NiS-modified TiO2 nanorods with a surface charge accumulation facet

“…No obvious spike was observed in the photocurrent of either pure TiO 2 NRs or TiO 2 /NiS- x composite structures, which indicates that the separation of their photogenerated electron–hole pairs is efficient. 57,58 Compared to bare TiO 2 NRs, TiO 2 /NiS is less stable and a decrease in current is observed in Fig. 7a, which is consistent with the results in Fig.…”

“…The radius of the arc in the Nyquist plot is related to the charge transfer resistance at the interface. 57,58 A smaller radius refers to a lower charge transfer resistance at the interface. As shown in Fig.…”

An S-scheme α-Fe2O3/Cu2O photocatalyst for an enhanced primary amine oxidative coupling reaction under visible light

“…Moreover, for α-Fe 2 O 3 , the doublets of Fe 2p3/2 and 2p1/2 at 710.1 and 724.1 eV, with the satellite peak at 718.6 and 732.7 eV, could be corresponded to the existence of Fe 3+ of α-Fe 2 O 3 . 29,54 These characteristic peaks of Fe 3+ are around 0.2–0.4 eV higher in the α-Fe 2 O 3 /Cu 2 O composite, due to decreasing of the electron cloud density around Fe. 55 Increasing of the electron cloud density around Cu and decreasing of the electron cloud density around Fe demonstrate the electrons transfer from α-Fe 2 O 3 to Cu 2 O, indicating the formation of S-scheme α-Fe 2 O 3 /Cu 2 O heterojunction.…”

“…Moreover, for α-Fe 2 O 3 , the doublets of Fe 2p3/2 and 2p1/2 at 710.1 and 724.1 eV, with the satellite peak at 718.6 and 732.7 eV, could be corresponded to the existence of Fe 3+ of α-Fe 2 O 3 . 29,54 These characteristic peaks of Fe 3+ are around 0.2-0.4 eV higher in the α-Fe 2 O 3 /Cu 2 O composite, due to decreasing of the electron cloud density around Fe. 55 The performance of the photocatalyst is evaluated by the oxidation coupling reaction of primary amine.…”

Recent advancements of g-C3N4-based magnetic photocatalysts towards the degradation of organic pollutants: a review

“…Recently, Rajiv et al have reported that the hydrothermally synthesized Fe 2 O 3 NPs decorated g-C 3 N 4 display a high SSA (416.3 m 2 g −1 ), and more active sites are expected to improve photocatalytic activity [110]. In contrast, Hou et al [140] have synthesized similar composite via calcination method and have reported relatively lower SSA with higher photocatalytic activity. This superior performance in activity is attributed to the highly suppressed charge carrier recombination via the Z-scheme charge transfer mechanism compared to the Type II system.…”