# Ultrasonically controlled synthesis of UO$_2$ + x colloidal nanoparticles

Manon Cot-Auriol, Matthieu Virot, Thomas Dumas, Olivier Diat, X. F Le Goff, Philippe Moisy, Sergey Nikitenko

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Manon Cot-Auriol, Matthieu Virot, Thomas Dumas, Olivier Diat, X. F Le Goff, et al., Ultrasonically controlled synthesis of UO$_2$ + x colloidal nanoparticles. Dalton Transactions, 2023, 52 (7), pp.2135-2144. 10.1039/d2dt03721a. hal-04721690

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https://hal.science/hal-04721690v1

Submitted on 4 Nov 2024

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Supporting Information

Ultrasonically-controlled synthesis of UO<sub>2+x</sub> colloidal nanoparticles

Manon Cot-Auriol<sup>a</sup>, Matthieu Virot<sup>a</sup>, Thomas Dumas<sup>b</sup>, Olivier Diat<sup>a</sup>, Xavier Le Goff<sup>a</sup>
Philippe Moisy<sup>b</sup>, Sergey I. Nikitenko<sup>a</sup>

Fitting approach for SAXS data

In general, the **Eq. S1** is used to define the scattering diagrams, with $I_0$ the initial intensity for Q approaching 0 value, P(Q) the form factor related to the size and shape of the analysed objects and S(Q) the structure factor related to particle interactions. The latter parameter is considered equal to 1, due to the low concentration of the scattering particles, which simplifies the equation.

$$I(Q) = I_0 P(Q) S(Q) \qquad (\text{Eq. S1})$$

In agreement with the experimental SAXS diagrams corresponding to spherical particles, a sphere form factor model was applied. In this case, $I_0$ is the result of the product described in **Eq. S2**, where $\phi_p$ is the volume fraction of the particles, $V_p$ is their volume and $\Delta\rho^2$ is the electronic contrast with the solvent. The parameters (molar volume, $V_m$ and scattering length density, $\rho_c$) used for the calculations of $\Delta\rho^2$ assuming UO<sub>2</sub> particles are presented in **Table S1**. The **Eq. S3** shows the definition of P(Q) used in the sphere model, with R the radius of the particle.

$$I_0 = \phi_p V_p \Delta\rho^2 \qquad (\text{Eq. S2})$$

$$P(Q) = \left[ \frac{3(\sin(QR) - QR\cos(QR))}{(QR)^3} \right]^2 \qquad (\text{Eq. S3})$$

<table><caption>Table S1: Molar volume ($V_m$), X-ray scattering length density ($\rho_c$) and electron contrast ($\Delta\rho^2$) used for SAXS diagram simulation calculations. Values for UO<sub>2</sub> are based on the oxide density (d = 10.96).<sup>1</sup></caption><thead><tr><th></th><th>V<sub>m</sub> (10<sup>-23</sup> cm<sup>3</sup>)</th><th>ρ<sub>c</sub> (10<sup>10</sup> cm<sup>-2</sup>)</th><th>Δρ<sup>2</sup>[UO<sub>2</sub>/H<sub>2</sub>O] (10<sup>23</sup> cm<sup>-4</sup>)</th></tr></thead><tbody><tr><td>UO<sub>2</sub></td><td>4.09</td><td>74.40</td><td>4.22</td></tr><tr><td>H<sub>2</sub>O</td><td>2.99</td><td>9.43</td><td>-</td></tr></tbody></table>

<footnote><sup>a</sup> ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France.</footnote>

<footnote><sup>b</sup> CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France.</footnote>
<figure><img src="image_1.png" /><figcaption>**Figure S1**</figcaption></figure>

Fig. S1: UV-Vis absorption spectrum measured for the concentrated U(IV) chloride solution in 1 M HCl.

<figure><img src="image_2.png" /><figcaption>**Figure S2**</figcaption></figure>

Fig. S2: Scheme and photography of the sonochemical setup at low ultrasonic frequency (20 kHz). The different inlets (size GL14) are used for gas circulation, temperature control and sampling.
<figure><img src="image_3.png" /><figcaption>**Figure S3**</figcaption></figure>

Fig. S3: UV-Vis absorption spectra measured directly after the dilution of concentrated U(IV) in pure water (in black), the corresponding spectra after subtraction of U(IV) reference spectrum (in green). The spectrum of U(VI) obtained in similar chloride medium (in orange) is provided for comparison.

<figure><img src="image_4.png" /><figcaption>**Figure S4**</figcaption></figure>

Fig. S4: UV-Vis absorption spectra acquired at different time on the final U(IV) chloride solution (5 mM) after the end of treatment under (a) 20 kHz sonolysis (65 °C, Ar/(10 %)CO, 0.36 W·mL⁻¹, pH = 1.5) and (b) mechanical stirring (silent conditions, 65 °C, Ar, pH = 1.5).

<caption>**Table S2**</caption>

Table S2: pH values of the U(IV) solutions (5 mM) measured before and after treatments by 20 kHz sonolysis (65 °C, Ar/(10 %)CO, 0.36 W·mL⁻¹) or mechanical stirring (silent conditions).

<table><thead><tr><th>Conditions</th><th></th><th>pH</th></tr></thead><tbody><tr><td>Before treatment</td><td>-</td><td>1.8</td></tr><tr><td rowspan="2">After sonolysis</td><td>-</td><td>1.5</td></tr><tr><td>With NaOH 0.1 M</td><td>9.5</td></tr><tr><td rowspan="2">After stirring</td><td>-</td><td>1.5</td></tr><tr><td>With NaOH 0.1 M</td><td>9.8</td></tr></tbody></table>
## Table S3

**Table S3:** Simulation results of SAXS diagrams obtained with a sphere model. $I_0$ the intensity for Q → 0, R the radius of the sphere. The sample "final" corresponds to the colloidal suspensions obtained after 2 hours of sonolysis (65 °C, Ar/(10 %)CO, 0.36 W·mL⁻¹, pH = 1.5) or mechanical stirring (silent conditions, 65 °C, Ar, pH = 1.5), with no other treatment. The time indicated represents the waiting time between the cessation of treatment (with or without US) and the SAXS analysis.

<table><thead><tr><th colspan="5">SAXS - Sphere model</th></tr><tr><th></th><th>Sample</th><th>I<sub>0</sub> (10<sup>-2</sup> cm<sup>-1</sup>)</th><th>Φ<sub>p</sub> (10<sup>-7</sup>)</th><th>R (nm)</th></tr></thead><tbody><tr><td rowspan="4">Sonolysis</td><td>Final</td><td>74</td><td>4.6</td><td>9.7 ± 0.1</td></tr><tr><td>Final + 90 min</td><td>70</td><td>4.4</td><td>9.7 ± 0.1</td></tr><tr><td>Final + 150 min</td><td>65</td><td>4.3</td><td>9.5 ± 0.1</td></tr><tr><td>Final + 210 min</td><td>-</td><td>-</td><td>-</td></tr><tr><td rowspan="4">Stirring</td><td>Final</td><td>5.0</td><td>4.8</td><td>3.9 ± 0.1</td></tr><tr><td>Final + 90 min</td><td>5.2</td><td>4.8</td><td>4.0 ± 0.1</td></tr><tr><td>Final + 150 min</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Final + 210 min</td><td>-</td><td>-</td><td>-</td></tr></tbody></table>

## Table S4

**Table S4:** d_n spacing values (for 1 ≤ n ≤ 4) of theoretical UO₂ and U(IV) precipitated solids obtained by adding NaOH 0.1 M after sonolysis (20 kHz, Ar/(10 %)CO, 0.36 W·mL⁻¹, pH = 9.5) or mechanical stirring (silent conditions, pH = 9.8).² For experimental samples, d_n values were measured on HR-TEM SAED patterns. The error is estimated equal to ± 0.20 Å.

<table><tbody><tr><th>Reference</th><th>UO<sub>2</sub></th><th>d<sub>n</sub> (Å)</th><th>3.15</th><th>2.73</th><th>1.93</th><th>1.65</th></tr><tr><td rowspan="4">HR-TEM</td><td rowspan="2">Sonolysis</td><th>d<sub>n</sub> (Å)</th><td>3.21</td><td>2.79</td><td>1.95</td><td>1.67</td></tr><tr><th>d<sub>1</sub>/d<sub>n</sub></th><td>-</td><td>1.15</td><td>1.64</td><td>1.91</td></tr><tr><td rowspan="2">Stirring</td><th>d<sub>n</sub> (Å)</th><td>3.22</td><td>2.78</td><td>1.96</td><td>1.67</td></tr><tr><th>d<sub>1</sub>/d<sub>n</sub></th><td>-</td><td>1.16</td><td>1.64</td><td>1.92</td></tr></tbody></table>

## References

1. L. R. Morss, N. M. Edelstein, J. Fuger and J. J. Katz, Eds., *The chemistry of the actinide and transactinide elements*, Springer, Dordrecht, 2006.

2. T. M. Nenoff, B. W. Jacobs, D. B. Robinson, P. P. Provencio, J. Huang, S. Ferreira and D. J. Hanson, *Chem. Mater.*, 2011, **23**, 5185–5190.