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oai:figshare.com:article/34031192 2026-09-30T10:05:12Z category_4 category_146 category_915 category_7 category_12 category_19 category_272 category_873 category_734 category_132 portal_63 item_type_6 month_year_09_2026

Resolving Overlapping Optical Transitions in CeO₂ by Derivative Analysis of UV–Vis Spectra: Application to Au/CeO₂ Hicham Idriss (1348734) Ahmed Ziani (1735258) Muhammad Amtiaz Nadeem (16556569) Biochemistry Space Science Physical Sciences not elsewhere classified Medicine Cell Biology Pharmacology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified Infectious Diseases associated band gap weaker transition associated mean particles size low energy side high energy side decreased defects centers second derivative gives </ sub >). 0 </ sup 2 </ sub first derivative plots 2 </ sup au largely suppressed 4 +</ sup 1 </ sup energy transition second derivative first derivative 2 ev largely unchanged higher energy defects states derivative analysis 4 wt 4 ). au particles tauc plots quantitative information light absorption investigated series half maximum full width 9 ev 6 ev 35 nm 22 nm 12 nm The effect of Au nanoparticles on the energy transition and associated band gap of CeO₂ has been studied by UV–vis absorbance then analyzed by the Tauc, first derivative (dA/dλ), and second derivative (d²A/dλ²) methods; A: absorbance and λ: wavelength. CeO₂ mean particles size is ca. 12 nm while those of Au were 4–7 nm for the investigated series (with Au wt % = 1, 2 and 4). For CeO₂, two clear transitions are observed and are attributed to O 2p to Ce 4f⁰ (Ce⁴⁺) and O 2p to 4f⁰/4f¹ (Ce⁴⁺ close to Ce³⁺/V_O; V_O: oxygen vacancy) with the former having a higher energy than the latter. The presence of Au largely suppressed the weaker transition associated with defects states (Ce³⁺/V_O). This was observed in the first derivative plots where a blue-shift of 22 nm is seen and a narrowing of the Full Width at Half Maximum of peaks by up to 35 nm when compared to CeO₂ alone. The second derivative plots showed a more pronounced shift at the low energy side with an extracted band gap energy of 2.9 eV that shifted to 3.2 eV for 4 wt % Au/CeO₂, while the high energy side (at ca. 3.6 eV) was largely unchanged. These changes, collectively attributed to Au particles, might be linked to decreased defects centers in Au/CeO₂ catalysts when compared to CeO₂ alone. Therefore, the first derivative gives qualitative assessment of the role of Au in CeO₂ for light absorption while the second derivative gives a more quantitative information on the optical transitions. On the contrary, the Tauc plots, while identified both transitions, were insensitive. 2026-09-30T00:00:00Z Text Journal contribution 10.1021/acs.jpcc.6c05148.s001 https://figshare.com/articles/journal_contribution/Resolving_Overlapping_Optical_Transitions_in_CeO_sub_2_sub_by_Derivative_Analysis_of_UV_Vis_Spectra_Application_to_Au_CeO_sub_2_sub_/34031192 CC BY-NC 4.0