Novel α-Fe2O3/polypyrrole nanocomposite with enhanced photocatalytic performance
Graphical abstract
Introduction
Semiconductor photocatalysts have recently attracted much interest due to the potential applications of detoxification of environmental pollutants [1], [2], [3]. Particularly, the importance of catalytic degradation of organic contaminations using semiconductors photocatalysts has stimulated great efforts to develop methods for their synthesis and characterization, making this area of study an integral part of photocatalysis [4], [5], [6], [7]. Among the photocatalysts, TiO2 is the most widely used semiconductor material for both fundamental research and applications because of its superior photoreactivity, nontoxicity, long-term stability, and low price [8], [9], [10], [11]. However, the band gap of TiO2 locates in the UV regime (∼5% of sun’s energy), which hinders the efficient practical applications.
Iron oxide (Fe2O3), on the other hand, is considered to be a potential photocatalyst owing to its narrow band gap energy (2.2 eV), chemical stability, and nontoxicity [12], [13]. Various Fe2O3 in the form of hematite nanostructures have been prepared by sono-electrochemical anodization using Fe foil and found that Fe2O3nanoporous structures have good photocatalytic activity in degradation of methylene blue (MB) under visible light [14]. Different shapes of Fe2O3 including hollow spindles and flowers have been used successfully for the photocatalytic performance towards phenol under UV-illumination [15], [16]. Mesoporous α-Fe2O3 nanorods have been recently reported to have remarkable photocatalytic activity for de-colorization of MB under visible light [17]. In another recent report, Niu et. al., fabricated heterostructures of Fe2O3 doped with SnO2 with an objective to separate charge carriers [18]. They obtained enhanced UV or visible light photocatalytic activity compared to pristine Fe2O3. Other heterostructures of Fe2O3 and TiO2 [19], [20] and CdS [21] have also been reported as efficient photocatalysts.
Conducting polymers with π-conjugated electron systems such as polypyrrole (PPy), polyaniline and polythiophene have been recognized among the most promising sensitizers [22], [23]. They are actually getting more interest as both supporting matrixes and electrocatalysts. Conducting polymers have also advantages of high absorption coefficients, high mobility of charge carriers and good environmental stability [24], [25], [26], [27], [28]. Various nanocomposites of semiconductors and conducting polymers have been reported previously [29], [30], [31], [32]. Particularly, one could find various studies concerning the photocatalytic performance of TiO2 sensitized by conducting polymers as immobilized films as well as in suspensions, under UV and visible-light illumination [33], [34], [35], [36], [37]. However, only few studies have been reported on just fabrication and characterization of conducting PPy–Fe2O3 based-nanocomposites [38], [39], [40], [41]. In the present study, we synthesized a system combining iron oxide and PPy as nanocomposite photocatalysts. PPy was selected because it shows good stability and processibility, and is expected to improve the photocatalytic performance of Fe2O3.
The aim of the present work is to provide a solid base of knowledge for the synthesis of α-Fe2O3/PPy nanocomposites that have remarkable photocatalytic activity towards MB together with efficient catalyst's recyclability. To better understand the conditions necessary for generating such effective photocatalysts, various ratios of pyrrole (Py) monomers were used during the formation of nanocomposites and systemically correlated to the final structure and material morphology. A simple, single step sol–gel approach was applied to simultaneously synthesize the α-Fe2O3 and polymerize the Py monomers. The as-prepared photocatalysts were consequently applied for the catalytic degradation of MB as a model pollutant, in aqueous solutions and under UV irradiation. Results of catalyst synthesis and characterization and its catalytic performance evaluation are thoroughly addressed.
Section snippets
Preparation of Fe2O3/PPy nanocomposite
All chemical reagents are of analytical grade and used without further purification. Fe2O3/PPy nanocomposite was prepared using a one-step chemical method in which a simultaneous gelation and polymerization take place. In a typical synthesis procedure, 0.1 M Fe(NO3)3·9H2O in 2-methoxy ethanol was firstly prepared. Various volumes of Py monomers were consequently added to different volumes of the above solution, to complete a total of 20 mL of mixed solution. Different volume ratios (Py:Fe
Structural and morphological characterization of α-Fe2O3/PPy nanocomposites
Thermo-gravimetric analysis (TG) and differential thermogravimetry (DTG) were performed to understand the thermal stability of the nanocomposite. Fig. 2 shows the TG and DTG curves of as-prepared gel with 25% Py sample. The TG (blue curve) demonstrates three-stages of weight loss. The first weight loss was detected between points 1 and 2 over the temperature range from room temperature to 250 °C, followed by sharp falls in sample weight over the temperature ranges from 250 to 565 °C (point 2–3)
Conclusions
Novel α-Fe2O3/PPy nanocomposite photocatalysts have been successfully prepared via one-step, wet chemical method involving a simultaneous gelation and polymerization process. α-Fe2O3/PPy nanocomposites with different volume ratios of Py monomers (5–40%) were synthesized and fully characterized using TG-DTG, XRD, TEM, EDX and N2 sorption analysis. With an emphasis on its utilization as efficient photocatalysts, the newly devolved nanocomposites showed a remarkable catalytic performance for the
Acknowledgements
The authors are thankful to the Deanship of Scientific Research for Grant: Research code NU/ESCI/13/15 (to Dr. F. A. Harraz), Najran University, Najran, Kingdom of Saudi Arabia. Advanced Materials and Nano-Research Centre, Najran University is gratefully acknowledged for instrumental facility.
References (55)
- et al.
Electrochim. Acta
(2000) - et al.
Appl. Catal. B: Environ.
(2010) - et al.
J. Alloys Compd.
(2010) - et al.
Appl. Catal. B: Environ.
(2004) - et al.
J. Photochem. Photobiol. A
(1997) Catal. Today
(1999)- et al.
J. Alloys Compd.
(2012) - et al.
J. Alloys Compd.
(2013) - et al.
Appl. Catal. A: Gen.
(2008) - et al.
J. Alloys Compd.
(2009)
Mater. Lett.
Mater. Res Bull.
Appl. Catal. B: Environ.
Chem. Eng. J.
J. Photochem. Photobiol. A.
J. Photochem. Photobiol. A.
Prog. Polym. Sci.
Electrochim. Acta
Scripta Mater.
Electrochim. Acta
Synth. Met.
J. Photochem. Photobiol. A
Electrochem. Commun.
Catal. Commun.
J. Solid. State. Chem.
Catal. Commun.
Polymer
Cited by (55)
Enhancement in photocatalytic activity and biological properties of Sm doped ZnO nanostructures by the increase in Sm contents
2023, Inorganic Chemistry CommunicationsFacile synthesis of Pd nanoparticles dispersed polypyrrole-carbon black/NiO nanocomposite with enhanced photocatalytic degradation of colored and colorless organic pollutants
2023, Colloids and Surfaces A: Physicochemical and Engineering AspectsAu nanoparticles dispersed polypyrrole-carbon black/SrTiO<inf>3</inf> nanocomposite photocatalyst with rapid and stable photocatalytic performance
2023, Journal of Saudi Chemical Society