Research on zinc electrodeposition for target preparation in medical isotope 67Cu production

Abstract

As an ideal dual-functional radionuclide for diagnostics and therapeutics, the clinical translation of ⁶⁷Cu is constrained by the stringent purity requirements of the ⁶⁸Zn target material during cyclotron production. To address the issues of impurity interference in traditional electrodeposition processes, this study developed an electrolyte system devoid of extraneous ionic impurities and organic additives. Under the pre-optimized basic parameters (current density 30 mA/cm², temperature 40 °C, Zn²⁺ concentration 20 g/L, mass ratio of ZnO to ammonium chloride 1:10), the regulation of pH 1-pH 5 on zinc target electrodeposition was systematically studied. The results show that under the optimal conditions, the deposition efficiency of Zn reaches 91.25 % within 2 h, and 99.69 % of Zn in the solution can be deposited on the substrate within 6 h. Compared with the traditional method, the deposition time is significantly shortened. Characterization through SEM, XRD, and EDS confirmed that the deposited layer is smooth and dense, with a uniform distribution of Zn elements; the coating consists of densely packed hexagonal zinc (space group P63/mmc). Electrochemical analyses revealed that the deposition of Zn²⁺ is diffusion-controlled and followed a continuous nucleation growth mechanism. Thermal shock experiments validated that the zinc target meets the adhesion strength and thermal stability requirements for proton irradiation conditions in a cyclotron. This process provides a reliable solution for the large-scale production of high specific activity ⁶⁷Cu utilizing ⁶⁸Zn target materials.