Electrochemistry of actinides on reduced graphene oxide: craving for the simultaneous voltammetric determination of uranium and plutonium in nuclear fuel

The aqueous electrochemistry of plutonium (Pu) has been explored for the first time on the reduced graphene oxide modified glassy carbon electrode (rGO/GC). It has been confirmed that rGO/GC can catalyse the Pu(IV)/Pu(III) redox reaction in 1 M H2SO4 and that finally leads to the high analytical sensitivity of anodic square wave voltammetric determination of Pu. However, the sensitivity of rGO/GC decreases in the actual nuclear fuel sample [i.e. Mark-I (U, Pu)C fuel dissolved in 1 M H2SO4] due to the interference of uranium (U). Furthermore, the cathodic square wave voltammograms of U(VI) in the sample solution have been found to be very inconsistent. That inconsistency is explained by the interfacial coupled chemical reaction between U(IV) (just produced at the working electrode) and Pu(IV) diffusing from the bulk of the solution to the vicinity of the working electrode. That is why the quantitative determination of uranium in the presence of plutonium is not feasible by simple voltammetric techniques on any working electrode. Although rGO/GC shows good analytical robustness, reproducibility, repeatability, fast analysis and least requirement of additional reagents; but challenge still exists in the analytical merits for the determination of Pu in nuclear fuel sample in competition with the biamperometric method.