The cathodic reduction of oxygen on uranium dioxide in dilute alkaline aqueous solution

The electrochemical reduction of hydrogen peroxide on uranium dioxide electrodes in alkaline solution

“…Previous electrochemical studies of O 2 reduction on UO 2 have demonstrated how this mixed U IV /U V oxide surface is catalytic for cathodic processes [19][20][21]. The theory of Presnov and Trunov for O 2 reduction on p-type semiconductors [22][23][24], which has been used to interpret the O 2 reduction mechanism on UO 2 electrodes [19][20][21], can also be invoked to understand the mechanism of H 2 O 2 reduction. According to this theory, electron transfer to the adsorbed O 2 molecule occurs at active sites formed by adjacent cations in different valence states.…”

“…If we assume that there is a dependence of U V /U IV on potential, and assign it the same Tafel slope measured for the surface reduction reaction Cu II /Cu I ($85 mV/decade, [25]) then a value of m = 0.75 is obtained, taking the Tafel slope for H 2 O 2 reduction to be 340 mV/decade. The potential dependent surface coverage of DAR sites on p-type UO 2 has previously been estimated as $156 mV/decade [20,21], from which a value of m = 0.54 is obtained. These values of m bracket the values reported in Table 2, indicating that our analysis is reasonable.…”

The effect of pH on the anodic dissolution of SIMFUEL (UO2)

“…The reaction has been shown to be catalyzed by the presence of U V surface states but would be expected to be blocked at U VI sites [6]. Consequently, it is not surprising that the measured reaction orders vary depending on the conditions of measurement.…”

“…The ability of O 2 and H 2 O 2 to act as cathodic reagents supporting the anodic dissolution of UO 2 has been shown to be very dependent on the chemical composition of the UO 2 surface [6][7][8][9]. As a-radiation fields decay with time, the corrosion potential of the fuel is predicted to evolve [4,10].…”

Kinetic Study of the Oxidative Dissolution of UO2 in Aqueous Carbonate Media

“…33,37 In addition, electrochemical studies of UO 2 corrosion in aqueous carbonate media have also been reported. 38,39 In the work presented herein, the efficacy of various oxidants, including NaOCl, K 2 S 2 O 8 , and H 2 O 2 , for dissolving UO 2 in aqueous carbonate solutions was evaluated. With hydrogen peroxide as the oxidant, the effects of both the carbonate countercation and the carbonate concentration on the initial dissolution rate and dissolution capacity were studied and optimized.…”