Enhanced photocatalytic performance by regulating the Ce³⁺/Ce⁴⁺ ratio in cerium dioxide

Abstract

Cerium dioxide (CeO₂) photocatalysts are used in treating environmental pollution and addressing the energy crisis due to their excellent oxygen storage capacities and abundant oxygen vacancies. In this paper, CeO₂ precursors were synthesized with different water-alcohol ratios via a solvothermal method, and CeO₂ photocatalysts with different Ce³⁺/Ce⁴⁺ ratios were obtained by changing the precursor calcination atmospheres (air, Ar) as well as the calcination time. The effects of CeO₂ with different Ce³⁺/Ce⁴⁺ ratios in photocatalytic degradations of methylene blue under visible light were investigated. X-ray photoelectron spectroscopy results showed that the surfaces of the samples calcined under Ar had higher Ce³⁺/Ce⁴⁺ ratios and oxygen vacancy concentrations, which reduced the band gaps of the catalysts and improved their utilization of visible light. In addition, the many Ce³⁺/Ce⁴⁺ redox centers and oxygen vacancies on the sample surfaces improved the separation and transfer efficiencies of the photogenerated carriers. The sample C2-Ar calcined under Ar showed a high adsorption capacity and excellent photocatalytic activity by removing 96% of the methylene blue within 120 min, which was more than twice the degradation rate of the sample (C2-air) prepared via calcination under air. Trapping experiments showed that photogenerated holes played a key role in the photocatalytic process. In addition, a synergistic photocatalytic mechanism for the Ce³⁺/Ce⁴⁺ redox centers and oxygen vacancies was elucidated in detail, and the sensitization of cerium dioxide by dyes aided the degradation of methylene blue.

Key words： CeO₂; oxygen vacancies; Ce³⁺/Ce⁴⁺ ratios; photocatalytic dye-sensitization

Competing interests

The authors declare that they have no competing interests.

Acknowledgements

This work is financially supported by National Natural Science Foundation of China (Grant No. 51974168), Science and Technology Major Project Inner Mongolia Autonomous Region in China (Grant Nos. 2019ZD023 and 2021ZD0028), and State Key Laboratory of Silicate Materials for Architectures (Wuhan University of Technology) (Grant No. SYSJJ2020-08).

References

1 Shanmugam M , Alsalme A , Alghamdi A , Jayavel R . Enhanced photocatalytic performance of the graphene-V₂O₅ nanocomposite in the degradation of methylene blue dye under direct sunlight. ACS Applied Materials & Interfaces, 2015, 7(27): 14905–14911

2 Li S , Guo Y , Zhang Q , Zhang L , Zhou P , Aleksandrzak M , Chen X . Enhanced photocatalytic performance of heterostructure CNNS@Bi₂WO₆ photocatalysts towards degradation of organic pollution. International Journal of Hydrogen Energy, 2023, 48(67): 26173–26186

3 Zhu C , Xian Q , He Q , Chen C , Zou W , Sun C , Wang S , Duan X . Edge-rich bicrystalline 1T/2H-MoS₂ cocatalyst-decorated {110} terminated CeO₂ nanorods for photocatalytic hydrogen evolution. ACS Applied Materials & Interfaces, 2021, 13(30): 35818–35827

4 Riffat M , Ali H , Qayyum H A , Bilal M , Hussain T . Enhanced solar-driven water splitting by ZnO/CdTe heterostructure thin films-based photocatalysts. International Journal of Hydrogen Energy, 2023, 48(58): 22069–22078

5 Reddy C V , Nagar A , Shetti N P , Reddy I N , Basu S , Shim J , Kakarla R R . Novel g-C₃N₄/BiVO₄ heterostructured nanohybrids for high efficiency photocatalytic degradation of toxic chemical pollutants. Chemosphere, 2023, 322: 138146

6 Geng J , Guo S , Zou Z , Yuan Z , Zhang D , Yan X , Ning X , Fan X . 0D/2D CeO₂/BiVO₄ S-scheme photocatalyst for production of solar fuels from CO₂. Fuel, 2023, 333: 126417

7 Huang L , Bao D , Jiang X , Li J , Zhang L , Sun X . Fabrication of stable high-performance urchin-like CeO₂/ZnO@Au hierarchical heterojunction photocatalyst for water remediation. Journal of Colloid and Interface Science, 2021, 588: 713–724

8 Humayun M , Hu Z , Khan A , Cheng W , Yuan Y , Zheng Z , Fu Q , Luo W . Highly efficient degradation of 2,4-dichlorophenol over CeO₂/g-C₃N₄ composites under visible-light irradiation: detailed reaction pathway and mechanism. Journal of Hazardous Materials, 2019, 364: 635–644

9 Zheng X , Mofarah S S , Cen A , Cazorla C , Haque E , Chen E Y , Atanacio A J , Manohar M , Vutukuri C , Abraham J L . . Role of oxygen vacancy ordering and channel formation in tuning intercalation pseudocapacitance in Mo single-ion-implanted CeO_2−x nanoflakes. ACS Applied Materials & Interfaces, 2021, 13(50): 59820–59833

10 Qi H , Shi C , Jiang X , Teng M , Sun Z , Huang Z , Pan D , Liu S , Guo Z . Constructing CeO₂/nitrogen-doped carbon quantum dot/g-C₃N₄ heterojunction photocatalysts for highly efficient visible light photocatalysis. Nanoscale, 2020, 12(37): 19112–19120

11 Li Y , Chen K , Wang X , Xiao Z , Liao G , Wang J , Li X , Tang Y , He C , Li L . Efficient removal of TBBPA with a Z-scheme BiVO₄-(rGO-Cu₂O) photocatalyst under sunlight irradiation. Chemosphere, 2022, 308: 136259

12 Wang B , Feng X , Xu Y , Shi J W . Role of Ce in promoting low-temperature performance and hydrothermal stability of Ce/Cu-SSZ-13 in the selective catalytic reduction of NO_x with NH₃. Separation and Purification Technology, 2023, 315: 123679

13 Peng R , Zhang H , Guo Y , Huang W , Zhang Y , Wu J , Fu M , Yu C , Ye D . The lanthanide doping effect on toluene catalytic oxidation over Pt/CeO₂ catalyst. Journal of Colloid and Interface Science, 2022, 614: 33–46

14 Salimi K . Self-assembled bio-inspired Au/CeO₂ nano-composites for visible white LED light irradiated photocatalysis. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020, 599: 124908

15 Shen C H , Chen Y , Xu X J , Li X Y , Wen X J , Liu Z T , Xing R , Guo H , Fei Z H . Efficient photocatalytic H₂ evolution and Cr(VI) reduction under visible light using a novel Z-scheme SnIn₄S₈/CeO₂ heterojunction photocatalysts. Journal of Hazardous Materials, 2021, 416: 126217

16 Xiao Y , Tan S , Wang D , Wu J , Jia T , Liu Q , Qi Y , Qi X , He P , Zhou M . CeO₂/BiOIO₃ heterojunction with oxygen vacancies and Ce⁴⁺/Ce³⁺ redox centers synergistically enhanced photocatalytic removal heavy metal. Applied Surface Science, 2020, 530: 147116

17 Yuan S , Xu B , Zhang Q , Liu S , Xie J , Zhang M , Ohno T . Development of the visible-light response of CeO_2−x with a high Ce³⁺ content and its photocatalytic properties. ChemCatChem, 2018, 10(6): 1267–1271

18 Talluri B , Yoo K , Kim J . Novel rhombus-shaped cerium oxide sheets as a highly durable methanol oxidation electrocatalyst and high-performance supercapacitor electrode material. Ceramics International, 2022, 48(1): 164–172

19 Choudhury B , Chetri P , Choudhury A . Oxygen defects and formation of Ce³⁺ affecting the photocatalytic performance of CeO₂ nanoparticles. RSC Advances, 2014, 4(9): 4663–4671

20 Matussin S N , Harunsani M H , Khan M M . CeO₂ and CeO₂-based nanomaterials for photocatalytic, antioxidant and antimicrobial activities. Journal of Rare Earths, 2023, 41(2): 167–181

21 Mei J , Shen Y , Wang Q , Shen Y , Li W , Zhao J , Chen J , Zhang S . Roles of oxygen species in low-temperature catalytic o-xylene oxidation on MOF-derived bouquetlike CeO₂. ACS Applied Materials & Interfaces, 2022, 14(31): 35694–35703

22 Zhang B , Zhang S , Liu B . Effect of oxygen vacancies on ceria catalyst for selective catalytic reduction of NO with NH₃. Applied Surface Science, 2020, 529: 147068

23 Yang C , Yang J , Duan X , Hu G , Liu Q , Ren S , Li J , Kong M . Roles of photo-generated holes and oxygen vacancies in enhancing photocatalytic performance over CeO₂ prepared by molten salt method. Advanced Powder Technology, 2020, 31(9): 4072–4081

24 Thompson T L , Yates J T Jr . TiO₂-based photocatalysis: surface defects, oxygen and charge transfer. Topics in Catalysis, 2005, 35(3–4): 197–210

25 Xu X , Ding X , Yang X , Wang P , Li S , Lu Z , Chen H . Oxygen vacancy boosted photocatalytic decomposition of ciprofloxacin over Bi₂MoO₆: oxygen vacancy engineering, biotoxicity evaluation and mechanism study. Journal of Hazardous Materials, 2019, 364: 691–699

26 Liu Y , Li Y , Liu X , Li J , Feng Y , Li X . In situ construction of rich oxygen vacancy Bi/Bi₃TaO₇ heterojunction photocatalysts. International Journal of Hydrogen Energy, 2023, 48(79): 30664–30676

27 Wang K , Chang Y , Lv L , Long Y . Effect of annealing temperature on oxygen vacancy concentrations of nanocrystalline CeO₂ film. Applied Surface Science, 2015, 351: 164–168

28 Xu N , Ma J , Liu Q , Luo Y , Pu Y . Preparation of CeO₂ abrasives by reducing atmosphere-assisted molten salt method for enhancing their chemical mechanical polishing performance on SiO₂ substrates. Journal of Rare Earths, 2023, 41(10): 1627–1635

29 Lim A M H , Zeng H C . Antisolvent route to ultrathin hollow spheres of cerium oxide for enhanced CO oxidation. ACS Applied Materials & Interfaces, 2021, 13(17): 20501–20510

30 Ma D , Sun D , Zou Y , Mao S , Lv Y , Wang Y , Li J , Shi J W . The synergy between electronic anchoring effect and internal electric field in CdS quantum dots decorated dandelion-like Fe–CeO₂ nanoflowers for improved photocatalytic hydrogen evolution. Journal of Colloid and Interface Science, 2019, 549: 179–188

31 Ye T , Huang W , Zeng L , Li M , Shi J . CeO_2−x platelet from monometallic cerium layered double hydroxides and its photocatalytic reduction of CO₂. Applied Catalysis B: Environmental, 2017, 210: 141–148

32 Wang X , Duan R , Liu W , Wang D , Wang B , Xu Y , Niu C , Shi J W . The insight into the role of CeO₂ in improving low-temperature catalytic performance and SO₂ tolerance of MnCoCeO_x microflowers for the NH₃-SCR of NO_x. Applied Surface Science, 2020, 510: 145517

33 Yang D , Xu Y , Pan K , Yu C , Wu J , Li M , Yang F , Qu Y , Zhou W . Engineering surface oxygen vacancy of mesoporous CeO₂ nanosheets assembled microspheres for boosting solar-driven photocatalytic performance. Chinese Chemical Letters, 2022, 33(1): 378–384

34 Murali A , Lan Y P , Sohn H Y . Effect of oxygen vacancies in non-stoichiometric ceria on its photocatalytic properties. Nano-Structures & Nano-Objects, 2019, 18: 100257

35 Lu M , Liu M , Wei Y , Xie H , Fan W , Huang J , Hu J , Wei P , Zhang W , Xie Y . . Photocatalytic activity and mechanism of cerium dioxide with different morphologies for tetracycline degradation. Journal of Alloys and Compounds, 2023, 936: 168273

36 Lan Y , Xia X , Li J , Mao X , Chen C , Ning D , Chu Z , Zhang J , Liu F . Insight into the contributions of surface oxygen vacancies on the promoted photocatalytic property of nanoceria. Nanomaterials, 2021, 11(5): 1168

37 Renuka N K , Praveen A K , Aniz C U . Ceria rhombic microplates: synthesis, characterization and catalytic activity. Microporous and Mesoporous Materials, 2013, 169: 35–41

38 Divya T , Anjali C , Sunajadevi K R , Anas K , Renuka N K . Influence of hydrothermal synthesis conditions on lattice defects in cerium oxide. Journal of Solid State Chemistry, 2021, 300: 122253

39 Tatar B , Sam E D , Kutlu K , Ürgen M . Synthesis and optical properties of CeO₂ nanocrystalline films grown by pulsed electron beam deposition. Journal of Materials Science, 2008, 43(15): 5102–5108

40 Hezam A , Namratha K , Drmosh Q A , Ponnamma D , Wang J , Prasad S , Ahamed M , Cheng C , Byrappa K . CeO₂ nanostructures enriched with oxygen vacancies for photocatalytic CO₂ reduction. ACS Applied Nano Materials, 2020, 3(1): 138–148

41 Wu D , Zhang X , Liu S , Ren Z , Xing Y , Jin X , Ni G . Fabrication of a Z-scheme CeO₂/Bi₂O₄ heterojunction photocatalyst with superior visible-light responsive photocatalytic performance. Journal of Alloys and Compounds, 2022, 909: 164671

42 Zhang W , Bian Z , Peng Y , Tang H , Wang H . Dual-function oxygen vacancy of BiOBr intensifies pollutant adsorption and molecular oxygen activation to remove tetracycline hydrochloride. Chemical Engineering Journal, 2023, 451: 138731

43 Reddy Yadav L S , Lingaraju K , Daruka Prasad B , Kavitha C , Banuprakash G , Nagaraju G . Synthesis of CeO₂ nanoparticles: photocatalytic and antibacterial activities. European Physical Journal Plus, 2017, 132(5): 1–10

44 Pan J , Wang S , Chen A , Chen Y , Wang M , Chen Y . Visible-light-active mesoporous ceria (CeO₂) nanospheres for improved photocatalytic performance. Journal of Alloys and Compounds, 2022, 898: 162895

45 Channei D , Nakaruk A , Phanichphant S . Photocatalytic degradation of dye using CeO₂/SCB composite catalysts. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017, 183: 218–224

46 Chen H H , Jiang Z H , Li X D , Lei X F . Effect of cerium nitrate concentration on morphologies, structure and photocatalytic activities of CeO₂ nanoparticles synthesized by microwave interface method. Materials Letters, 2019, 257: 126666

47 Killivalavan G , Sathyaseelan B , Kavitha G , Baskarann I , Senthilnathan K , Sivakumar D , Karthikeyan N , Manikandan E , Maaza M . Cobalt metal ion doped cerium oxide (Co–CeO₂) nanoparticles effect enhanced photocatalytic activity. MRS Advances, 2020, 5(48–49): 2503–2515

48 Trandafilović L V , Jovanović D J , Zhang X , Ptasińska S , Dramićanin M D . Enhanced photocatalytic degradation of methylene blue and methyl orange by ZnO:Eu nanoparticles. Applied Catalysis B: Environmental, 2017, 203: 740–752