# Enhancing Methyl Orange Degradation with Laser-Generated ZnO and Ce-Doped ZnO Nanoparticles
## 4 Conclusions  
In this study, we successfully synthesized ZnO NPs and Ce-doped ZnO NPs using CW and high-power CO\({}_{2}\) laser decomposition methods. XRD analysis confirmed the successful incorporation of Ce ions into ZnO, revealing a secondary phase identified as CeO\({}_{2}\) at a 1 wt % dopant concentration. Additionally, there was a variation in the optical band gap, transitioning from 3.7 eV for pure ZnO to 2.6 eV for undoped ZnO NPs, further decreasing  
Figure 10: Mechanisms of dye degradation on the surface of (**a**) undoped ZnO NPs photocatalyst and (**b**) doped 1% Ce/ZnO NPs photocatalyst.  
to 2 eV for 1% Ce/ZnO NPs. This shift suggests that both doping and CO\({}_{2}\) laser treatment influence particle size reduction and band gap modification. The investigation explored the effects of Ce doping on ZnO's morphology, nanostructure, and optical properties. The photocatalytic activities of Ce-doped ZnO were evaluated for the degradation of MO dye, as the target pollutant, under both UV and sunlight exposure, utilizing annealed and non-annealed photocatalysts. Notably, the incorporation of Ce ions acted as an electron reservoir, reducing the rate of electron-hole pair recombination. Based on the experimental findings, it was determined that 1 wt % Ce doping represents the optimal condition for achieving maximum photoinduced oxidative catalytic degradation and complete MO dye degradation. The synthesis process offers a combination of low cost and high efficiency, yielding degradation of 92% under UV light and 95% under sunlight, positioning Ce-doped ZnO as a promising candidate for environmental remediation applications.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app132111857/s1](https://www.mdpi.com/article/10.3390/app132111857/s1)]([https://www.mdpi.com/article/10.3390/app132111857/s1](https://www.mdpi.com/article/10.3390/app132111857/s1)), Section S1. Synthesis of un-doped ZnO solution; Section S2. Synthesis Ce doped ZnO solution; Table S1: XRD data crystal parameters of undoped ZnO nanoparticles.; Table S2: XRD data crystal parameters of Ce 1% doped ZnO nanoparticles.; Table S3: Details measurement of ZnO NPs and 1%Ce-ZnO NPs via ImageJ software; Table S4: Lattice parameters, crystalline sizes, average particle sizes, and optical energy band gaps.; Table S5: Comparison of 1% Ce-doped ZnO NPs with other photocatalysts for the MO degradation. References [46;47] are cited in the supplementary materials.  
Conceptualization, N.M.A. and F.K.Y.; Methodology, A.H.A.; Software, I.A.W.; Validation, N.M.A., F.K.Y., Z.U.Z., I.A.W., K.H.I. and H.C.; Formal analysis, A.H.A.; Investigation, A.H.A.; Resources, A.M.B., O.A. and K.H.I.; Data curation, Z.U.Z.; Writing--original draft, A.H.A.; Writing--review & editing, H.C.; Visualization, H.C.; Supervision, N.M.A., F.K.Y., O.A. and K.H.I.; Project administration, Z.U.Z., A.M.B., O.A. and K.H.I.; Funding acquisition, A.M.B., O.A. and K.H.I. All authors have read and agreed to the published version of the manuscript.  
The authors extend their appreciation to the Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia for funding this research through the project number IFP-IMSIU-2023083. The authors also appreciate the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University (IMSIU) for supporting and supervising this project.  
Not applicable.  
The authors are grateful to the School of Physics (USM) for research facilities. Also, the authors also appreciate the valuable assistance from [PERSON] (University of Trieste, Italy) throughout this work.  
The authors declare no conflict of interest.