Synergetic effect of Fe₂O₃ and BiVO₄ as photocatalyst nanocomposites for improved photo-Fenton catalytic activity

Abstract

Photo-Fenton reactions and the related functional nanomaterials have been widely studied for applications in wastewater treatment industry. Herein, visible-light-responsive Fe₂O₃ nanoparticle-decorated BiVO₄ nanoplates were designed and successfully prepared through a one-pot hydrothermal route. The as-prepared Fe₂O₃/BiVO₄ nanocomposites exhibit excellent photo-Fenton catalytic activity toward the discoloration of methylene blue (MB) and Rhodamine B (RhB) dye molecules in the presence of H₂O₂. The experimental results indicate that nearly 100% of MB (100 mL, 10 mg L⁻¹) and RhB (100 mL, 5 mg L⁻¹) dye molecules are degraded in the presence of 1 g L⁻¹ Fe₂O₃/BiVO₄-1 (FB-1) photo-Fenton catalyst and 0.5 mL of H₂O₂ within 20 min. The Fe₂O₃/BiVO₄ Fenton photocatalyst also demonstrates high reusability under visible light irradiation with λ ≥ 420 nm. The photoinduced electrons on the conduction band of BiVO₄ nanoplates can move toward the surface of Fe₂O₃/BiVO₄ to accelerate the reduction of Fe³⁺; then, the as-formed Fe²⁺ ions on the surface of the catalyst greatly enhance the decomposition of H₂O₂ to form reactive ^·OH species for the use in photodegradation of MB and RhB dye molecules. The synergetic effect of Fe₂O₃ and BiVO₄ reported in this work might provide more opportunity to fabricate other novel semiconductor-based Fenton nanocomposites for contamination treatments in wastewater.

Introduction

Recently, photo-Fenton reactions involving hydrogen peroxide (H₂O₂) and Fe²⁺ ions to produce highly reactive oxygen species (generally ^·OH), as well as the related materials themselves, have been widely used in wastewater treatment industry to decompose various organic pollutants [1,2,3]. However, the utilization of large amount of iron inorganic salts in the treated wastewater might bring about the production of Fe-containing sludge in which Fe ions are difficult to be recycled. Moreover, most of the Fenton reaction systems must be performed under acidic medium [3]. These shortcomings greatly inhibit the application of the photo-Fenton catalytic technology even though it has the characteristics of easier operation and fast reaction rate. Thus, developing new photo-Fenton catalysts with high chemical oxidant of ^·OH generation efficiency, expanded acidity effective range, and multiple recyclability is of great significance.

In addition, fast chemical reduction of Fe³⁺ ions to Fe²⁺ either in aqueous solution or on the surface of catalysts is expected to be a facile route to promote the Fenton catalytic performance [4, 5]. Previous investigations have demonstrated that the introduction of UV or visible-light-responsive photocatalyst with large amounts of excited electrons is a promising strategy [6,7,8], which can reduce Fe³⁺ ions to Fe²⁺ in a quick way under a nearly neutral condition and further accelerate the photo-Fenton procedure. Meanwhile, the photocatalysts as the additional platform for photo-Fenton reactions can be shaped into different morphologies, including nanotubes, nanowires, nanobelts, and nanoplates [9,10,11,12]. These nanosized catalysts usually had superior photocatalytic activities than those of the bulk materials due to their large surface area and stronger light absorption capacity [13]. Notably, the nanoplates featuring ultrathin thickness and high structural anisotropy have been paid an increasing attention to be used as the platform materials [14]. Hydrothermal method is regarded as a simple pathway toward morphology-controlled synthesis of nanoplates [15].

In this work, a feasible one-pot hydrothermal synthetic route was carried out to construct Fe₂O₃ nanoparticle-decorated BiVO₄ photo-Fenton system in FeCl₃–Bi(NO₃)₃–NH₄VO₃ aqueous solution. As is known to all, bismuth vanadate (BiVO₄), as visible-light-responsive photocatalysts, possessed relatively narrow band gap energy (< 2.5 eV) and high photocatalytic activity in the evolution of H₂ and O₂, as well as degradation of organic contaminants [16, 17]. Therefore, BiVO₄ is considered to be one of the most promising candidates to fabricate novel photo-Fenton system [18]. Under light irradiation, the photogenerated electrons in the conduction band of BiVO₄ nanoplates are transferred to the surface to enhance the chemical reduction of Fe³⁺ to Fe²⁺ ions, and as-formed redundant Fe²⁺ then reacts with H₂O₂ to accelerate its decomposition into reactive ^·OH species, which is further applied for the photodegradation of organic pollutant. Methylene blue (MB) and Rhodamine B (RhB) belong to two important basic dyes with N-methyl and N-ethyl groups in their molecular structures, respectively. They have been widely used in various industries for coloring and further cause plenty of disposal environmental problems. Thus, MB and RhB dye molecules are selected as the model pollutions to investigate the photocatalytic activity of Fe₂O₃-decorated BiVO₄ (denoted as Fe₂O₃/BiVO₄ nanocomposites) in the following study. The mechanism of the photo-Fenton catalytic process is also investigated through the corresponding verification experiments and discussed in detail.

Experimental

Materials

The starting materials include ferric chloride (FeCl₃·6H₂O, 99.0%, Zhiyuan, Tianjin, China), bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O, 99.0%, Damao, Tianjin, China), ammonium metavanadate (NH₄VO₃, Aladdin, Shanghai, China), sodium hydroxide (NaOH, 99.5%, Guoyao, Shanghai, China), and distilled water. All of the reagents are analytical-grade regents and used as received without any purification.

Preparation of Fe₂O₃/BiVO₄ nanocomposites

The Fe₂O₃/BiVO₄ nanocomposites were prepared through a simple hydrothermal strategy in the FeCl₃–Bi(NO₃)₃–NH₄VO₃–H₂O synthetic system. Typically, a certain amount of FeCl₃·6H₂O (1–5 mmol) and Bi (NO₃)₃·5H₂O (5 mmol) was added into 60 mL of distilled water under magnetic stirring condition, and a yellow suspension was formed. Then, 5 mmol of NH₄VO₃ was added, and an orange suspension was formed. Then, the pH value of the mixture is adjusted to about 6.0 by using sodium hydroxide solution (5 M), which was then placed in a Teflon-lined autoclave with maximum volume of about 100 mL and heated at 160 °C for 12 h in an electric heating oven. The resultant yellow Fe₂O₃/BiVO₄ powder was collected, washed with distilled water and ethanol triple times, respectively, and dried at 60 °C for 2 h for further characterization. Samples of different molars of FeCl₃·6H₂O (1 mmol, 2 mmol, 3 mmol, 4 mmol, 5 mmol) were denoted as FB-1, FB-2, FB-3, FB-4, FB-5, respectively. Pure BiVO₄ was also prepared by a similar procedure without the addition of FeCl₃·6H₂O.

Characterization

The phase structures of the plate-like BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites were investigated by powder X-ray diffraction performed on a X’Pert Pro MRDDY2094 diffractometer with Cu-Kα radiation (λ = 1.5418 Å). We recorded the XRD patterns of the samples in the 2θ range of 15°–80° under a scan rate of 0.0167 s⁻¹. The morphology of the plate-like BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites was characterized by using the Ultra Plus field-emission scanning electron microscope (FE-SEM) accompanied with an energy-dispersive spectroscopy (EDS) to analyze the chemical composition. High-resolution transmission electron microscope (HRTEM) images were measured under the accelerating voltage of 200 kV on a JEOL JSM-2100F microscope. X-ray photoelectron spectroscopy (XPS) was conducted to identify the surface elemental composition. The UV–visible adsorption spectra of these samples were characterized using a Hitachi U-3100 UV–visible spectrometer. The photo-Fenton activities of BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites were measured by monitoring the MB or RhB concentration at their maximum absorption with a UV–Vis spectrophotometer.

Photocatalytic properties

The dyes of Rhodamine B (RhB) and methylene blue (MB) were chosen as typical pollutants to evaluate the photo-Fenton catalytic performance of the Fe₂O₃/BiVO₄ nanocomposites. In detail, 0.1 g of the Fe₂O₃/BiVO₄ catalyst was introduced into a 100 mL of MB (10 mg L⁻¹) or RhB (5 mg L⁻¹) aqueous solution. The mixture was under continuous stirring for 30 min in the darkness to achieve the dye adsorption equilibrium. The degradation experiments were subsequently started at neutral aqueous solutions (pH 7) under a 300-W Xe lamp light irradiation with a cutoff filter (λ = 420–700 nm) at room temperature. A certain amount of H₂O₂ aqueous solution (30%) was injected into the above solution when the light irradiation began. Then, 3 mL of the treated solution was taken out at each time interval of 10 min and centrifuged at 9500 rpm for 5 min to remove the photocatalysts. The concentrations of MB or RhB dye molecules in the treated solution with maximum adsorption at about 554 nm and 664 nm were detected by UV–Vis spectrum, respectively. The recycling experiments of Fe₂O₃/BiVO₄ nanocomposites for degradation of the dye molecules were also performed in the same way, and the suspension was centrifuged with the catalysts recovered and used for the next run.

Results and discussion

Structure and morphology

The XRD patterns of pure BiVO₄ nanoplates, Fe₂O₃/BiVO₄ nanocomposites, and the simulated XRD pattern of BiVO₄ with JCPDS No. 75-1866 are shown in Fig. 1. It can be noticed that the as-prepared BiVO₄ nanoplates have the monoclinic structure of BiVO₄ (JCPDS No. 75-1866) as the main phase mixed with small amount of FeV₃O₈ phase (JCPDS No. 36-0007) as iron doping level increases [19, 20], which was marked with red asterisk. The peaks marked with blue asterisk are ascribed to Fe₂O₃ (JCPDS No. 85-0987) [21, 22], respectively. Also, the sharp and strong diffraction peaks illustrated the crystallinity of Fe₂O₃/BiVO₄ nanocomposites.

Figure 1

(From down to top) XRD patterns of plate-like BiVO₄ with JCPDS No. 75-1866, Fe₂O₃/BiVO₄ nanocomposites named as FB-1, FB-2, FB-3, FB-4, and FB-5, respectively. (Red asterisk, FeV₃O₈ with JCPDS No. 36-0007; blue asterisk, Fe₂O₃ with JCPDS No. 85-0987)

The morphologies of the BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites were characterized by FE-SEM. Figure 2a shows the irregular morphology of plate-like BiVO₄ samples. The SEM images of the Fe₂O₃/BiVO₄ nanocomposites by introducing different amounts of FeCl₃·6H₂O are shown in Fig. 2b–f, which are different from the pure BiVO₄ nanoplates, and large amounts of Fe₂O₃ nanoparticles appeared on the surface of the plates. Furthermore, as the doping level of Fe³⁺ ions increases in the synthetic system, the Fe₂O₃ nanoparticles aggregated together and formed a thin Fe₂O₃ layer over the surface of BiVO₄ nanoplates. In addition, the high-resolution transmission electron microscope images (HRTEM) of FB-1 are shown in Fig. 3a, b, in which the darker nanoparticles and the lighter plates correspond to Fe₂O₃ nanoparticles and BiVO₄, respectively. The lattices of BiVO₄ and Fe₂O₃ can also be clearly seen in Fig. 3b, suggesting the high crystallinity of Fe₂O₃/BiVO₄ composites. The selected SEM image and the corresponding overlapped elemental mapping image of FB-1 are shown in Fig. 3c and d, respectively. It can be observed that the elements of Fe (Red), Bi (Green), V (Blue), and O (Yellow) are coexisted in FB-1, indicating that these elements are all included in the final composite.

Figure 2

SEM images of a pure BiVO₄ nanoplates, b FB-1, c FB-2, d FB-3, e FB-4, and f FB-5, respectively

Figure 3

a TEM and b HRTEM images of FB-1 sample; c selected SEM image and d the corresponding overlapped elemental mapping image of FB-1; and e–h elemental mapping images of Bi, Fe, V, and O, respectively. (Green dot: Bi, red dot: Fe, blue dot: V, and yellow dot: O)

XPS, UV–Vis, and PL spectra

The XPS spectrum was measured to identify the surface chemical composition of Fe₂O₃/BiVO₄ nanocomposites. As shown in Fig. 4a, the XPS survey spectrum of FB-1 also demonstrates the coexistence of the elements including Fe, Bi, V, and O, which is in consistency with the result of EDS measurement. The high-resolution XPS spectrum of Fe 2p shows the two main peaks of Fe 2p_1/2 and Fe 2p_3/2 at 724.3 and 710.9 eV, respectively. A satellite peak of Fe 2p_3/2 demonstrated the existence of Fe³⁺ in Fe₂O₃/BiVO₄ nanocomposites (Fig. 4b) [23]. In Fig. 4c, the peaks with binding energies of 159.2 and 164.5 eV corresponded to the Bi 4f_7/2 and Bi 4f_5/2 in FB-1, respectively [24]. The two characteristic peaks in the high resolution of V 2p spectrum shown in Fig. 4d with binding energies of 516.9 and 524.0 eV can be attributed to V2p_3/2 and V2p_1/2 for V⁵⁺ state in FB-1 [25]. The asymmetric O 1s peak shown in Fig. 4e can be ascribed to lattice oxygen with binding energy of 529.8 eV in FB-1 and the physically adsorbed oxygen in the near-surface region [26].

Figure 4

XPS survey spectrum of a FB-1 sample and the high-resolution spectra of b Fe, c Bi, d V, and e O for FB-1 nanocomposite

The UV–Vis adsorption spectra of BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites are shown in Fig. 5a. Compared to the pure BiVO₄ nanoplates, the adsorption bands of Fe₂O₃/BiVO₄ nanocomposites exhibited a red shift and an enhanced UV–Vis light adsorption, suggesting that the Fe₂O₃ nanoparticle-decorated BiVO₄ nanoplates would have high light utilization ability and promoted photocatalytic activity for degradation of dye molecules. In addition, the band gap of the samples was calculated from the plots of (αhv)² versus photoenergy (hv), and the corresponding estimated band gap values of the Fe₂O₃/BiVO₄ nanoplates are between 2.07 and 2.39 eV, which is slightly narrowed in comparison with that of pure BiVO₄ (2.44 eV) (Fig. 5b–e) [27].

Figure 5

a UV–Vis diffuse reflectance spectra of BiVO₄ nanoplates and Fe₂O₃/BiVO₄ nanoplates with different doping amounts of Fe₂O₃ nanoparticles; corresponding Mott–Schottky plots for b BiVO₄ nanoplates and c–e Fe₂O₃/BiVO₄ nanoplates

Photo-Fenton catalytic property and stability of Fe₂O₃/BiVO₄ nanocomposites

The photo-Fenton catalytic activity of the BiVO₄ and Fe₂O₃/BiVO₄ nanocomposites for degradation of MB molecules with the presence of 0.5 mL H₂O₂ is shown in Fig. 6a. The pure BiVO₄ nanoplates presented a degradation efficiency of approximately 76.7% for MB after the photo-Fenton reaction time of 40 min. However, the Fe₂O₃/BiVO₄-1 (FB-1) nanocomposites showed greatly enhanced photo-Fenton activity, and the degradation ratio of MB reached nearly 100% in 40 min. With the Fe₂O₃ nanoparticles decorated on the surface of BiVO₄ increasing from the sample of FB-2 to FB-5, the photo-Fenton catalytic performance decreased. Also, the photo-Fenton catalytic degradation of MB can be well ascribed to the first-order kinetics (Fig. 6b). The degradation rate constant on FB-1 is approximately 4.7 times to that of pure BiVO₄ nanoplates. Series of photo-Fenton degradation experiments were carried out to study the influence of H₂O₂, visible light irradiation, and the Fe₂O₃/BiVO₄ catalyst toward MB degradation. As shown in Fig. 6c, the dosage of H₂O₂ played a significant role in the photodegradation reaction, and when the amount of H₂O₂ increased from 0.1 to 0.5 mL, the photo-Fenton degradation efficiency increased from approximately 57.9 to 90.9% in 20 min. However, the degradation of MB did not change too much on further increasing the dosage of H₂O₂ to 2 mL. In addition, more photo-Fenton degradation procedures were implemented to identify the effects of visible light irradiation, H₂O₂, and FB-1 on MB degradation, respectively. As shown in Fig. 6d, if only H₂O₂ was introduced into the reaction system, the dye molecules can hardly be decomposed under visible light irradiation or in the dark, indicating that pure H₂O₂ were unable to efficiently achieve its significant decomposition. The degradation efficiency of MB greatly increased with the presence of Fe₂O₃/BiVO₄ nanocomposites no matter whether H₂O₂ is introduced or not in the darkness, revealing that the nanocomposite has catalytic performance for MB dye molecules. When the visible light irradiation was started to the reaction system, the degradation ratio of MB proceeded very fast, illustrating the dominant role of visible light, which can greatly promote the degradation rate.

Figure 6

a Photo-Fenton catalytic performances of BiVO₄ and Fe₂O₃/BiVO₄ nanoplates for degradation of MB molecules with the addition of 0.5 mL H₂O₂; b kinetics of Fenton degradation of MB dye molecules; c effect of H₂O₂ amount on degradation of MB over FB-1 sample; and d degradation of MB under different reaction conditions

Furthermore, the photo-Fenton catalytic activity of Fe₂O₃/BiVO₄ nanocomposites for degradation of RhB molecules in the presence of 0.2 mL H₂O₂ is carried out and the experimental results are shown in Fig. 7a. The FB-1 nanocomposite also presented the best Fenton catalytic performance. The degradation efficiency toward RhB is approximately 98.4%, which is only about 14.8% over pure BiVO₄. The degradation rate constant on FB-1 is more than 15 times to that of pure BiVO₄ (Fig. 7b). Figure 7c provides the effect of H₂O₂ dosage for degradation of RhB, and when the dosage of H₂O₂ in the system increased from 0.1 mL to 0.2 mL, the degradation of RhB over FB-1 increased from approximately 37.4% to nearly 100% under 20-min irradiation. Further increasing the amount of H₂O₂ from 0.2 to 2 mL, the degradation efficiency of RhB decreased. It is found that the ^·OH radicals are the dominant active species in Fenton reaction [28], and the decreasing of hydroxyl radicals in concentration is expected to be the main reason that results in the lowering of degradation efficiency of MB and RhB in the above-discussed experiments. High concentration of H₂O₂ is a scavenger of ^·OH radicals because the excessive H₂O₂ would capture the free ^·OH radicals with the formation of H₂O and O₂ based on the equation (Eq. 1) [29]:

$$ {\text{H}}_{2} {\text{O}}_{2} + 2^{ \cdot } {\text{OH}} \to 2{\text{H}}_{2} {\text{O}} + {\text{O}}_{2} $$

(1)

Figure 7d demonstrates the degradation efficiency of RhB over FB-1 nanocomposites which is greatly increased when appropriate amount of H₂O₂ was introduced under light irradiation. The recycling Fenton reactions were carried out to evaluate the stability and recyclability of the Fe₂O₃/BiVO₄ nanocomposites. As shown in Fig. 8, the FB-1 nanocomposite catalysts exhibit excellent recyclability toward degradation of MB (Fig. 8a) and RhB (Fig. 8b), and the degradation efficiency of Fe₂O₃/BiVO₄ toward MB and RhB is nearly 100% for the first time of photocatalytic experiment and is still above 85% even after five cycles, in which the slight decrease in degradation efficiency might be caused by the weight loss of catalysts.

Figure 7

a Photo-Fenton catalytic performances of BiVO₄ and Fe₂O₃/BiVO₄ nanoplates for degradation of RhB molecules with the addition of 0.2 mL H₂O₂; b kinetics of Fenton degradation of RhB molecules; c effect of H₂O₂ amount on degradation of RhB over FB-1 sample; and d degradation of RhB under different reaction conditions

Figure 8

Recycled performance of FB-1 for Fenton catalytic degradation of a MB and b RhB dye molecules

Mechanism of photo-Fenton catalytic activity of Fe₂O₃/BiVO₄ nanocomposites

The enhanced photocatalytic ability is mainly caused by the generation of highly oxidizing ^·OH radicals produced in the photo-Fenton reaction, as also reported in the previous Ref. [30]. To further clearly identify the photo-Fenton catalytic mechanism of MB and RhB dye molecules under light irradiation, ^·OH radicals trapping experiments were carried out by using tert-Butyl alcohol (TBA, 0.005 g) as the scavenger with other conditions unchanged [31]. As shown in Fig. 9a and b, the Fenton degradation of dye molecules is increased with the increase in reaction time. However, after TBA is introduced, the degradation of MB and RhB is significantly suppressed, demonstrating that ^·OH radicals worked as the main oxidation sources for accelerating the Fenton reaction. Based on the above trapping experimental results, the photo-Fenton degradation mechanism of dye molecules was proposed. Under the irradiation of visible light, only H₂O₂ solution was introduced, and the system showed a limited photocatalytic activity toward dye degradation. However, the degradation rate of dye over Fe₂O₃/BiVO₄ catalyst increased significantly when adding both H₂O₂ and visible light irradiation. It is obvious that the Fe₂O₃/BiVO₄ nanocomposites can catalytically activate H₂O₂ to produce ^·OH, which can be used for the Fenton reactions. The flat-band potential values of pure Fe₂O₃ and BiVO₄ can be obtained from the extrapolation of Mott–Schottky plots reported in Ref. [32, 33], which are approximately − 0.40 V (vs. Ag/AgCl) and − 0.58 V (vs. Ag/AgCl) at pH 7.0, respectively. Because the flat-band potential of the n-type semiconductor is very close to the bottom edge of the conduction band, the redox potential of conduction band of Fe₂O₃ and BiVO₄ versus normal hydrogen electrode is calculated to be − 0.16 V and − 0.34 V, respectively. The more negative conduction band and valence band of BiVO₄ result in the facile injection of photoinduced electrons from the conduction band of BiVO₄ to that of decorated Fe₂O₃ nanoparticles to reduce Fe³⁺. The reductant Fe²⁺ then reacts with H₂O₂ to form the active ^·OH radicals, participating in capturing and decomposing the dye molecules. The proposed mechanism can be described by the equations shown as follows:

$$ {\text{BiVO}}_{4} + {\text{hv}} \to {\text{BiVO}}_{4} \left( {{\text{e}}^{ - }_{\text{CB}} + {\text{h}}^{ + }_{\text{VB}} } \right) $$

(2)

$$ {\text{Fe}}^{3 + } + {\text{e}}^{ - }_{\text{CB}} \to {\text{Fe}}^{2 + } $$

(3)

$$ {\text{H}}_{2} {\text{O}}_{2} + {\text{e}}_{\text{CB}}^{ - } \to \, ^{ \cdot } {\text{OH}} + {\text{OH}}^{ - } $$

(4)

$$ {\text{Fe}}^{2} + {\text{H}}_{2} {\text{O}}_{2} \to {\text{Fe}}^{3 + } +^{ \cdot } {\text{OH}} + {\text{OH}}^{ - } $$

(5)

$$ {\text{MB}}\;{\text{or}}\;{\text{RhB}} +^{ \cdot } {\text{OH}} \to {\text{degradation}}\;{\text{products}} $$

(6)

Figure 9c shows the proposed process for the photo-Fenton reaction in Fe/BiVO₄/H₂O₂/MB or Fe/BiVO₄/H₂O₂/RhB system. In the dark environment, MB or RhB dye molecule was firstly adsorbed on the surface of the Fe₂O₃/BiVO₄ nanocomposites to reach adsorption equilibrium. Subsequently, under the visible light irradiation, BiVO₄ catalyst was excited to generate large amounts of free electron–hole pairs and the electrons were transferred to the surface of catalyst to reduce Fe³⁺ to Fe²⁺ according to Eqs. (2) and (3). As the electron acceptor, H₂O₂ captured the ${\text{e}}^{ - }_{\text{CB}}$ to form ^·OH and OH⁻ (Eq. 4), and the reduced Fe²⁺ as shown in Eq. (3) further reacted with H₂O₂ to form more ^·OH radicals (Eq. 5); then, the generated ^·OH radicals attacked and decomposed the MB or RhB dye molecules to form the final degradation products according to Eq. (6).

Figure 9

Hydroxyl radical trapping experiments of a FB-1/H₂O₂/MB system and b FB-1/H₂O₂/RhB system; c the photo-Fenton catalytic mechanism for MB and RhB dye molecules over Fe₂O₃/BiVO₄ composite

Conclusions

In summary, Fe₂O₃ nanoparticles-decorated BiVO₄ nanoplates were successfully fabricated as the photo-Fenton reaction platform to demonstrate the synergetic effect of photogenerated electrons and reduction of Fe³⁺ to Fe²⁺ for the improved catalytic activity. The Fe₂O₃/BiVO₄ nanocomposite catalysts exhibited efficient photo-Fenton catalytic performance for degradation of MB and RhB dye molecules, which could be attributed to the transformation of the photoinduced electrons from BiVO₄ semiconductors to reduce Fe³⁺ to Fe²⁺, and then, the reductant Fe²⁺ reacts with H₂O₂ to form the active ^·OH radicals, which captured and decomposed the dyes. Furthermore, the Fe₂O₃/BiVO₄ nanocomposites showed superior photo-Fenton catalytic stability on the elimination of dyes, maintaining high activities even after five cycles, and the trapping experiments demonstrated the important roles of active hydroxyl species. Also, the visible light irradiation displays a dominant role in activating the semiconductor-based Fenton catalytic system, which can motivate the BiVO₄ photocatalyst to generate free electrons and achieve the recycling of Fe³⁺/Fe²⁺, thus enhancing the Fenton catalytic performance of Fe₂O₃/BiVO₄ nanocomposites.