With the depletion of energy resources and escalating environmental issues, the development of new energy sources and advanced energy storage devices has become increasingly critical. Zinc-ion batteries have attracted significant attention due to their lower cost and safer chemistry. A major focus of zinc-ion battery research is the development of zinc anodes and electrolyte design. Zinc-free anodes have emerged as a promising strategy, offering higher zinc utilization compared to traditional zinc metal anodes (approximately 10%). Among many zinc-free anodes, Ti₃C₂Tx, a MXene (transition metal nitride/carbide layered material), stands out due to its lower lattice mismatch (~10%), higher conductivity, superior mechanical properties, and good hydrophilicity. However, the higher zinc utilization of zinc-free anodes presents challenges for the stable plating/stripping of zinc. Co-solvent engineering is a convenient and direct approach to improving the stability of zinc-free anodes.

In this study, we propose the use of PEG and IPA as co-solvents added to a 1M Zn(OTF)₂-H₂O electrolyte to enhance the stability of Ti₃C₂Tx zinc-free anodes. We found that the addition of PEG reduced the hydrogen evolution current by 0.42 mA (at -1.3 V vs. Ag wire), indicating suppression of the hydrogen evolution reaction. Furthermore, the addition of PEG in the electrolyte inhibits the 2D diffusion of zinc on the Ti₃C₂ surface and promotes zinc deposition along the (002) crystal direction, increasing the (002)/(001) ratio from 0.59 to 0.86, leading to more uniform zinc deposition. Consequently, the Ti₃C₂ zinc-free anode achieved a coulombic efficiency of 97.67% and a cycle life of 268 hours. Similarly, the addition of IPA reduced the hydrogen evolution current by 0.39 mA (at -1.3 V vs. Ag wire), indicating a weaker hydrogen evolution reaction. Moreover, the addition of IPA in the electrolyte inhibits 2D diffusion on the Ti₃C₂ surface and facilitates zinc deposition along the (002) crystal direction, increasing the (002)/(001) ratio from 0.59 to 0.87. The formation of an SEI containing ZnCO₃, ZnFx, and F-rich organics helps to homogenize the Zn ion gradient. Ultimately, the Ti₃C₂ zinc- free anode achieved a high coulombic efficiency of 98.95% and a cycle life of over 1200 hours in the IPA-containing electrolyte.

Holmium-166 is a promising radionuclide for therapeutic and imaging applications due to its advantageous decay characteristics. However, these applications require or would benefit from a higher specific activity of ¹⁶⁶Ho than that obtained via a ¹⁶⁵Ho(n,γ)¹⁶⁶Ho reaction by irradiating a pure ¹⁶⁵Ho target. The specific activity is limited, because only a minor fraction of the ¹⁶⁵Ho target nuclides is converted into ¹⁶⁶Ho during irradiation and these isotopes are inseparable using conventional chemical methods, since they are of the same element. The Szilard-Chalmers effect facilitates this separation by changing the chemical state of the produced radionuclide due to the recoil induced by neutron absorption. Nevertheless, currently applied target materials, mainly ligands, are unsuitable for commercial scale production with sufficient yield and specific activity, because of: radiolysis, isotopic interchange and recombination. It is proposed that these processes can be significantly reduced by exploiting zeolites, which are materials with interconnected cavities, to bind ¹⁶⁵Ho target nuclides in the closed cages prior to irradiation. The concept behind is, that upon recoil the ¹⁶⁶Ho nuclides relocate to the open cages, from which they are extracted after irradiation, while the ¹⁶⁵Ho target nuclides remain locked in the closed cages. This results in an increased specific activity. Therefore, the aim of this thesis is to examine the increase in the specific activity of ¹⁶⁶Ho produced via a (n,γ) reaction by applying the Szilard-Chalmers effect using zeolite A.

A procedure to achieve the optimal loading of holmium into the open cages (18.3 wt% Ho) and closed cages (93.3% of total holmium) of zeolite A was investigated, as well as the efficiency of its extraction from the open cages (between 39 and 55%). The obtained specific activity and yield were analysed upon irradiation of these zeolite A samples. Irradiating zeolite A with ¹⁶⁵Ho exclusively in the open cages resulted in only a slight increase of the specific activity (maximal 3.3 GBq/g), but a relatively good yield (maximal 53%). In contrast, irradiation of zeolite A with ¹⁶⁵Ho loaded in both the closed and the open cages, resulted in a considerably lower yield (maximal 14.4%), but a substantially increased specific activity (maximal 7.3 GBq/g), which is a factor 5.2 higher than without the Szilard-Chalmers effect. 
Nevertheless, further improvement should be considered as a higher specific activity is key to successful radionuclide therapy. This could potentially be achieved by increasing the extraction efficiency by exploring other types of zeolites, in search of more suitable functional characteristics.