A critical review on relationship of CeO2-based photocatalyst towards mechanistic degradation of organic pollutant
Graphical abstract
Introduction
The water quality has been significantly worsening recently with the pace of urban development and population growth (Im et al., 2021; Yuan et al., 2021). Various industrial processes discharged a high amount of wastewater into the environment containing high toxicity, thereby causing severe environmental pollution. For example, different types of organic pollutants, including phenols, antibiotics, benzene, and dyes that are high toxicity and challenging to degrade, could contaminate marine life and the ecosystem (Ma et al., 2019b). Therefore, developing an effective strategy to eliminate pollutants from wastewater is necessary.
Advanced oxidation processes (AOPs) are promising chemical treatment processes for wastewater pollutants by oxidation through hydroxyl radical reactions (·OH) in the presence of homogeneous and heterogeneous photocatalysis (Pham et al., 2021). Among AOPs, heterogeneous photocatalysis has emerged as an excellent tool for degradation of emerging pollutant due to effectiveness, eco-friendly and low cost (Acar and Dincer, 2018; Mehdi Sabzehmeidani et al., 2020). Semiconductor catalysts such as titanium dioxide (TiO2) (Badvi and Javanbakht, 2021), zinc oxide (ZnO) (Truong et al., 2021), iron oxides (Fe2O3) (Hitam and Jalil, 2020), and Copper oxide (CuO) (Liu et al., 2021) are often used in photocatalytic treatment because of their excellent characteristics, including chemical stability and superficial preparation.
In recent years, a rare earth oxide cerium oxide (CeO2) is promising for its wide application in catalysts (Yang et al., 2021a, Yang et al., 2021a). it has been extensively used in various application, for instance, electrocatalysis, fuel cells (Escudero et al., 2021; Wang et al., 2020a, Wang et al., 2020b), solar cells (Zhao et al., 2016), dry reforming of methane (Marinho et al., 2021) and photocatalysis (Labhane and Sonawane, 2020). This is due to the superior properties of CeO2, such as low toxicity, cheap, strong oxygen storage capacity, high chemical stability, and stable Ce3+/Ce4+ redox couple, which could be beneficial to the formation of abundant oxygen vacancies in CeO2 (Bui et al., 2021; Lin et al., 2020; Yang et al., 2018). Meanwhile, the existed abundant oxygen vacancies can reduce electron-hole recombination and enhance photocatalytic activity. However, the performance of single CeO2 is still unsatisfactory with many disadvantages, such as low specific surface area, large bandgap (2.8–3.1 eV) with lower absorption in visible regions up to 400 nm, and high electron-hole recombination (Wen et al., 2017a). Hence, the modification of CeO2 is needed to overcome these above shortcomings.
In recent years, various strategies such as adding support material (Phanichphant et al., 2016), controlling morphologies (Choudhary et al., 2020; Fang et al., 2015), doping metals, and non-metal and fabricating heterojunctions have been employed. Besides, these modifications may provide a different type of heterojunction and movement of charge carriers, which plays a crucial role in the photodegradation process. Despite the enormous interest in this modification, the properties and reaction mechanisms are still debatable and unresolved. Previously, most researchers did not critically explain the current CeO2 modification without doping, give a clear statement of the significance of CeO2 modification by doping other materials and provide a detailed mechanism for each heterojunction formed after doping.
Thus, inspired by the above-mentioned issues, the present review study reports the recent modification of CeO2-based materials for the photodegradation of various contaminants. The main objective of this study is to represent an appraisal of the current efforts in engineering various heterojunction photocatalysts and their corresponding mechanism in photocatalysis. The above-mentioned five crucial types of heterojunctions in photocatalysts are reviewed and discussed. Finally, the current status, opportunities, and future directions of these heterojunction photocatalysts are presented. It is believed that this research would draw more attention to the application of CeO2 photocatalysts and provide high knowledge on photocatalytic degradation in wastewater.
Section snippets
CeO2 as photocatalyst
Ceria (CeO2) is well known rare-earth metal oxides in the earth's crust. It is noteworthy that CeO2 minerals are commonly present in carbonates, phosphates, hydroxides, and silicates, and have traditionally been extracted and processed for pharmaceutical and industrial applications. As mentioned above, CeO2 is currently considered as one of the promising semiconductors for various applications, especially in photocatalytic degradation. This is due to unique structural characteristics, including
Modification of CeO2-based photocatalyst
It has been noted that the modification of CeO2 photocatalyst is required to overcome those shortcomings and enhanced the performance for targeted pollutants. Several attempts have been made to change the electronic band alignment to suppress electron-hole recombination and encourage electron-hole separation, which could dramatically improve photocatalytic efficiency. The efficiency of CeO2 can be enhanced by alteration using several alternatives such as non-metal doping, metal doping, adding
Conservative heterojunction
Based on the last part, it obviously can be noticed that the modification of CeO2-based photocatalyst by combining two or more materials to form heterojunction shows superior performance compared to a single structure. The performance enhancement was due to the synergistic effects between heterostructures, the high absorptivity of visible light, good stability and effective electron-hole separation and migration (Deng et al., 2015). In general, it is well known that a heterojunction is a
Conclusion and future prospect
Although all of the modification of CeO2 morphology has been done, the photocatalytic performance of a single CeO2 still dissatisfaction. Numerous modified CeO2 has been studied to enhance photodegradation efficiency, including metals and non-metals doping, adding support material, and construction with other semiconductors. In this review, the photodegradation mechanism on a single CeO2 photocatalyst and modified CeO2 was clarified. Subsequently, the latest developments in the modification and
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was supported by Fundamental Research Grant Scheme FRGS/1/2019/STG07/UTM/01/1-5F192 and Collaborative Research Grant (No. 07G59 and 08G92) from Ministry of Higher Education Malaysia.
References (122)
- et al.
Photoactive materials
Compr. Energy Syst.
(2018) - et al.
The effect of sunlight induced surface defects on the photocatalytic activity of nanosized CeO2 for the degradation of phenol and its derivatives
Appl. Catal. B
(2016) - et al.
Green synthesis of garlic extract stabilized Ag@CeO2 composites for photocatalytic and sonocatalytic degradation of mixed dyes and antimicrobial studies
J. Mol. Struct.
(2020) - et al.
Tuning of the electronic band structure of fibrous silica titania with g-C3N4 for efficient Z-scheme photocatalytic activity
Appl. Surf. Sci.
(2020) - et al.
Applied Surface Science Controllable structure of fi brous SiO2 – ZSM-5 support decorated with TiO2 catalysts for enhanced photodegradation of paracetamol
Appl. Surf. Sci.
(2018) - et al.
Enhanced photocatalytic degradation of dye contaminants with TiO2 immobilized on ZSM-5 zeolite modified with nickel nanoparticles
J. Clean. Prod.
(2021) - et al.
Preparation and optimization of CeO2 nanoparticles and its application in photocatalytic degradation of Reactive Orange 16 dye
Powder Technol.
(2013) - et al.
Oxygen vacancy engineering of cerium oxide for the selective photocatalytic oxidation of aromatic pollutants
J. Hazard Mater.
(2021) - et al.
Synergistic effect of CeO2 modified TiO2 photocatalyst on the enhancement of visible light photocatalytic performance
J. Alloys Compd.
(2017) - et al.
Template-free and surfactant-free synthesis of CeO2 nanodiscs with enhanced photocatalytic activity
Appl. Surf. Sci.
(2020)
Synthesis of monodisperse CeO2 hollow spheres with enhanced photocatalytic activity
Ceram. Int.
Synergistic effect of p-n heterojunction, supporting and zeolite nanoparticles in enhanced photocatalytic activity of NiO and SnO2
J. Colloid Interface Sci.
Spray solution combustion synthesis of hollow porous MoO3 photocatalyst
Ceram. Int.
Long-term operation of a solid oxide fuel cell with MoNi–CeO2 as anode directly fed by biogas containing simultaneously sulphur and siloxane
J. Power Sources
Facile synthesis of CeO2 hollow structures with controllable morphology by template-engaged etching of Cu2O and their visible light photocatalytic performance
Appl. Catal. B Environ.
BiVO4 – graphene catalyst and its high photocatalytic performance under visible light irradiation
Mater. Chem. Phys.
Facile sol-gel preparation of Cd-doped cerium oxide (CeO2) nanoparticles and their photocatalytic activities
J. Alloys Compd.
Enhanced photocatalytic activity of supported TiO2 by selective surface modification of zeolite y
Appl. Surf. Sci.
A review on exploration of Fe2O3 photocatalyst towards degradation of dyes and organic contaminants
J. Environ. Manag.
Highly efficient degradation of 2 , 4-dichlorophenol over CeO2/g-C3N4 composites under visible-light irradiation : detailed reaction pathway and mechanism
J. Hazard Mater.
Review of MXene-based nanocomposites for photocatalysis
Chemosphere
High-silica zeolites for adsorption of organic micro-pollutants in water treatment: a review
Water Res.
Novel ternary BiOI/g-C3N4/CeO2 catalysts for enhanced photocatalytic degradation of tetracycline under visible-light radiation via double charge transfer process
J. Alloys Compd.
A new approach in sono-photocatalytic degradation of recalcitrant textile wastewater using MgO@Zeolite nanostructure under UVA irradiation
Chem. Eng. J.
Tuning of photocatalytic performance of CeO2-Fe2O3 composite by Sn-doping for the effective degradation of methlene blue (MB) and methyl orange (MO) dyes
Surfaces Interfaces
Elucidation of role of graphene in catalytic designs for electroreduction of oxygen
Curr. Opin. Electrochem.
Fabrication of raspberry-shaped reduced graphene oxide labelled Fe/CeO2 ternary heterojunction with an enhanced photocatalytic performance
Inorg. Chem. Commun.
Facile synthesis of CeO2/carbonate doped Bi2O2CO3 Z-scheme heterojunction for improved visible-light photocatalytic performance: photodegradation of tetracycline and photocatalytic mechanism
J. Colloid Interface Sci.
Fabrication of Fe3O4/CuO@C composite from MOF-based materials as an efficient and magnetically separable photocatalyst for degradation of ciprofloxacin antibiotic
Chemosphere
Building novel Ag/CeO2 heterostructure for enhancing photocatalytic activity
Mater. Res. Bull.
The enhanced photocatalytic performance toward carbamazepine by nitrogen-doped carbon dots decorated on BiOBr/CeO2: Mechanism insight and degradation pathways
Chem. Eng. J.
Construction of CuO@CuS/PVDF composite membrane and its superiority for degradation of antibiotics by activation of persulfate
Chem. Eng. J.
Surface modification and enhanced photocatalytic CO2 reduction performance of TiO2 : a review
Appl. Surf. Sci.
Biotemplating synthesis of N-doped two-dimensional CeO2–TiO2 nanosheets with enhanced visible light photocatalytic desulfurization performance
J. Alloys Compd.
Magnetic NiFe2O4/BiOBr composites: one-pot combustion synthesis and enhanced visible-light photocatalytic properties
Separ. Purif. Technol.
A critical review on visible-light-response CeO2 -based photocatalysts with enhanced photooxidation of organic pollutants
Catal. Today
A novel natural sunlight active photocatalyst of CdS/SWCNT/CeO2 heterostructure: in depth mechanistic insights for the catalyst reactivity and dye mineralization
Appl. Surf. Sci.
Synthesis and characterization of Ag/CeO2/graphene nanocomposites as catalysts for water-pollution treatment
Appl. Surf. Sci.
CeO2 nanofibers-CdS nanostructures n–n junction with enhanced visible-light photocatalytic activity
Arab. J. Chem.
Origin of enhanced photocatalytic activity of F-doped CeO2 nanocubes
Appl. Surf. Sci.
Synthesis and characterization of nanocrystalline and mesostructured CeO2: influence of the amino acid template
Mater. Chem. Phys.
Zeolite-Y incorporated karaya gum hydrogel composites for highly effective removal of cationic dyes
Colloids Surfaces A Physicochem. Eng. Asp.
Facile sonochemical synthesis of Cu doped CeO2 nanostructures as a novel dual-functional photocatalytic adsorbent
Ultrason. Sonochem.
Ce, Ti modified MCM-48 mesoporous photocatalysts: effect of the synthesis route on support and metal ion properties
Appl. Surf. Sci.
Ag/CeO2 nanostructured materials for enhanced photocatalytic and antibacterial applications
Ceram. Int.
A mechanistic study and in-vivo toxicity bioassay on acetamiprid photodegradation over the zeolite supported cerium-based photocatalyst
J. Photochem. Photobiol. Chem.
Activation of potassium peroxymonosulfate for rhodamine B photocatalytic degradation over visible-light-driven conjugated polyvinyl chloride/Bi2O3 hybrid structure
Sustain. Chem. Pharm.
Photocatalytic activity of the binary composite CeO2/SiO2 for degradation of dye
Appl. Surf. Sci.
Microwave-assisted hydrothermal synthesis and characterization of CeO2 nanowires for using as a photocatalytic material
Mater. Lett.
Influence of CeO2 loading on the structural, textural, optical and photocatalytic properties of single-pot sol-gel derived ultrafine CeO2/TiO2 nanocomposites for the efficient degradation of tetracycline under visible light irradiation
Mater. Sci. Semicond. Process.
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