Fabrication, characterization and photocatalytic activity of g-C₃N₄ coupled with FeVO₄ nanorods

Abstract

A novel FeVO 4 /g-C 3 N 4 composite photocatalyst was synthesized via a simple mixing-calcination method and characterized by various techniques including Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UVvis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and an electrochemical method. The photocatalytic activity was evaluated by degradation of rhodamine B (RhB). Results indicated that 10 FeVO 4 /g-C 3 N 4 composite exhibited a much higher photocatalytic activity than pure g-C 3 N 4 under visible light illumination. The rate constant of RhB degradation for the optimal FeVO 4 /g-C 3 N 4 composite (5.0%FeVO 4 /g-C 3 N 4 ) is approximately 2.2 times that of pure g-C 3 N 4 . The formation of a heterojunction structure between FeVO 4 and g-C 3 N 4 which efficiently promoted the separation of electron-hole pairs was believed to be origin of the enhanced photoactivity.

Fabrication of Direct Z‐scheme α‐Fe2O3/FeVO4 Nanobelts with Enhanced Photoelectrochemical Performance

“…The survey spectrum of α‐Fe 2 O 3 /FeVO 4 (Figure a) indicates that the photocatalysts are composed of Fe, V, and O elements. It can be obviously found from Figure b that the doublet peaks located at 723.8 and 710.7 eV are attributed to Fe2p 1/2 and Fe2p 3/2 , respectively . Furthermore, the V 2p spectrum is consisted of 2p 1/2 and2p 2/3 , corresponding to 524.3 eV and 516.7 eV, respectively .…”

“…For the semiconductor materials, the energy band gap (Eg) is calculated according to the Kubelka‐Munk (KM) method by the following equation: αE photon =K (E photon −E g ) n/2 , in which α, E photon and E g are absorption coefficient, the discrete photon energy, and band gap energy, respectively and K is a constant. The value of the index n depends on the electronic transition of the semiconductor (n=1 for direct transition and n=4 for indirect transition) and as for FeVO 4 , the value of n is 1 . The energy gap of the samples is calculated as 2.03, 2.10 and 2.29 eV for α‐Fe 2 O 3 , α‐Fe 2 O 3 /FeVO 4 and FeVO 4 , respectively.…”

“…Free radicals trapping experiments are performed to demonstrate the above photocatalytic mechanism experimentally. Silver nitrate (AgNO 3 ), ammonium oxalate (AO), isopropyl alcohol (IPA) and benzoquinone (BQ) are employed as the scavengers for electron (e − ), hole (h + ), hydroxyl radical (⋅OH) and superoxide ion radical (⋅O 2 − ), respectively ,. As depicted in Figure b, no obvious change is observed in the presence of AgNO 3 , indicating that e − does not contribute much to the MB decomposition.…”

“…Triclinic FeVO 4 has caused a wide concern due to its narrow band gap (E g =2.1 eV) and inherent visible light absorption attaining to about 600 nm . However, the photocatalytic performance of pure FeVO 4 is still limited due to the high recombination rate of photoexcited carriers, so it is very feasible for FeVO 4 nanomaterials to overcome the performance bottleneck by constructing the complex heterostructures with different morphologies, such as Bi 2 O 3 /FeVO 4 nanoparticles, g‐C 3 N 4 /FeVO 4 nanorods, W‐doped FeVO 4 films and N‐doped Fe 2 O 3 /FeVO 4 rod‐like nanoparticles, etc.…”

Investigating cation-substituted metal vanadate photoanodes for solar water splitting

“…with BiVO4, Fe2O3, g-C3N4, and Bi2O3 has been published as photocatalysts for efficient organic pollutant degradation. [94][95][96][97][98][99] The stable and inexpensive material also attracts interest for photoelectrochemical water splitting due to their suitable bandgap of Fe2V4O13 is 1.8 eV and FeVO4 ~2.0 -2.1 eV (Figure 2.10). [100][101] Iron(II) vanadate was first systematically investigated by Craig D. Morton et al as thin film photoanodes.…”