Gamma radiation can have an influence on the integrity of the copper canisters used in deep geological repositories for isolating radioactive waste. Understanding the interactions between aqueous radiolysis products and container materials, particularly at the copper-water interface, is essential for assessing the canister integrity. This study investigates the gamma-radiation-induced products on copper specimens and water through experimental methods. Cu specimens were exposed to gamma radiation, and corrosion products were analysed using cathodic reduction, XPS, ICP-MS, and FT-IR. Results show that Cu2O is the dominant corrosion product formed during irradiation. Pre-oxidized Cu specimens, especially those formed at evaluated temperatures (140 °C), exhibited less corrosion depths and much more homogeneous coloration on the surfaces compared to literature data of irradiated bare Cu specimens and pre-oxidized 90 °C Cu specimens, suggesting the possibility that high temperature pre-oxidation enhances corrosion resistance under irradiation conditions. Additionally, the enhanced formation of alkane species, such as CH4, was observed in irradiated water, likely originated from the reduction of CO2 and HCO3− by radiation-induced reducing agents (H, H2, and eaq−). This observation raises new questions about the chemical transformations occurring under irradiation. The findings highlight the importance of understanding initial Cu oxide layer properties and suggest that optimizing temperature and environmental conditions in DGRs can improve the long-term performance of Cu canisters. Future studies are encouraged to explore localized corrosion mechanisms in Cl−-rich environments and to further investigate the implications of alkane production on the chemical stability of DGR systems.

Gamma-induced modification of graphitic carbon nitride (g-C3N4) has emerged as a novel strategy for enhancing its photocatalytic performance. In this study, g-C3N4 was subjected to gamma-ray treatment at doses ranging from 1 to 50 kGy, utilising Cs-137 as the radiation source. The structural and surface properties of the irradiated g-C3N4 were extensively characterized, revealing significant alterations including exfoliation of surface layers (from 12.5 m2 g-1 to 15.0 m2 g-1), enlargement of crystalline size (from 14.9 nm to 17.0 nm), and distortion and partitioning of s-triazine units. Notably, gamma-induced modifications caused 2 times enhancement in the generation of superoxide anion radicals, which can most likely be attributed to improved separation of electron-hole pairs, as evidenced by enhanced photocatalytic degradation of various pollutants, including 5-fluorouracil (1.9 times higher), imatinib mesylate (2 times higher), and Cr(vi) (2.8 times higher). Samples irradiated with the doses of 1 kGy and 50 kGy showed the highest photoactivity, indicating the effectiveness of gamma-induced modification in enhancing the photocatalytic performance of g-C3N4. Furthermore, the stability of the irradiated samples was enhanced, with the sample irradiated at 50 kGy maintaining excellent photocatalytic activity over five continuous cycles. This study highlights the potential of gamma-induced modification as a sustainable and effective strategy for enhancing the performance of g-C3N4-based photocatalysts in environmental remediation applications.

During in situ liquid-phase electron microscopy (LP-EM) observations, the application of different irradiation dose rates may considerably alter the chemistry of the studied solution and influence pro-cesses, in particular growth pathways. While many processes have been studied using LP-EM in the last decade, the extent of the influence of the electron beam is not always understood and comparisons with corresponding bulk experiments are lacking. Here, we employ the radiolytic oxidation of Ce3+ in aqueous solution as a model reaction for the in situ LP-EM study of the formation of CeO2 particles. We compare our findings to the results from our previous study where a larger volume of Ce3+ precursor solution was subjected to ?-irradiation. We systematically analyze the effects of the applied irradiation dose rates and the induced diffusion of Ce ions on the growth mechanisms and the morphology of ceria particles. Our results show that an eight orders of magnitude higher dose rate applied during homogeneous electron-radiation in LP-EM compared to the dose rate using gamma-radiation does not affect the CeO2 particle growth pathway despite the significant higher Ce3+ to Ce4+ oxidation rate. Moreover, in both cases highly ordered structures (mesocrystals) are formed. This finding is explained by the stepwise formation of ceria particles via an intermediate phase, a signature of non-classical crystallization. Furthermore, when irradiation is applied locally using LP scanning transmission electron microscopy (LP-STEM), the higher conversion rate induces Ce-ion concentration gradients affecting the CeO2 growth. The appearance of branched morphologies is associated with the change to diffusion limited growth.

Transition metal-based catalysts show great potential to replace Pt-based material in energy conversion devices thanks to their low cost, reasonable intrinsic activity, thermodynamic stability, and corrosion resistance. The electrochemical performance of such catalysts is sensitive to their composition and structure. Here, it is demonstrated that homogeneous alloy nanoparticles with varying Ni-to-Co ratio and controlled structure can be synthesized from aqueous Ni(Co) acetate solutions using a facile γ-radiolytic reduction method. The obtained samples are found to possess defects that are ordered to form polytypes structures. The concentration of these defects depends on the Ni-to-Co ratio, as supported by the results of ab initio calculations. It is found that structural defects may influence the activity of catalysts toward the oxygen evolution reaction, while this effect is less pronounced with respect to the oxygen reduction reaction. At the same time, the activity of Ni–Co catalysts in the hydrogen evolution reaction is affected by formation of Ni-OH bonds on the surface rather than by the presence of structural defects. This study demonstrates that the composition of Ni-Co nanoparticles is an essential factor affecting their structure, and both composition and structure can be tuned to optimize electrochemical performance with respect to various catalytic reactions.

Ag nanoparticles (Ag NPs) are among the most promising candidates to replace Pt as the catalyst for the oxygen reduction reaction (ORR) in anion exchange membrane fuel cells (AEMFCs). However, synthesizing size-controlled Ag NPs with efficient catalytic performance is still challenging. Herein, uniform Ag NPs are produced through a γ-radiation induced synthesis route in aqueous solutions, using the ionomer PTPipQ100 as both an efficient size regulator in the synthesis and a conductor of hydroxide ions during the ORR process. The origin of the size control is mainly attributed to the affinity of the ionomer to metallic silver. The resulting Ag NPs covered with ionomer layers can be applied as model catalysts for ORR. The nanoparticles that were prepared using 320 ppm ionomer in the reaction solution turned out to be coated with a ∼ 1 nm thick ionomer layer and exhibited superior ORR activity as compared to other Ag NPs of similar size studied here. The improved electrocatalytic performance can be attributed to the optimal ionomer coverage that enables fast oxygen diffusion, as well as interactions at the Ag-ionomer interface which promote the desorption of OH intermediates from the Ag surface. This work demonstrates the advantage of using an ionomer as the capping agent to produce efficient ORR catalysts.

To reach commercial viability for fuel cells, one needs to develop active and robust Pt-free electrocatalysts. Silver has great potential to replace Pt as the catalyst for the oxygen reduction reaction (ORR) in alkaline media due to its low cost and superior stability. However, its catalytic activity needs to be improved. One possible solution is to fabricate bimetallic nanostructures, which demonstrate a bifunctional enhancement in the electrochemical performance. Here, two types of bimetallic silver-nickel nanocatalysts, core-shells (Ag@NiO) and heterostructures (Ag/Ni), are fabricated using γ-radiation induced synthesis. The Ag@NiO nanoparticles consist of an amorphous, NiO layer as a shell and a facetted crystalline Ag particle as a core. Meanwhile, the Ag/Ni heterostructures comprise Ag particles decorated with Ni/Ni(oxy-hydro)-oxide clusters. Both materials demonstrate similar and increased alkaline ORR activity as compared to monometallic catalysts. It was revealed that the enhanced catalytic activity of the core-shells is mainly attributed to the electronic ligand effect. While in the Ag/Ni heterostructures, a lattice mismatch between the Ni-based clusters and Ag implies a significant lattice strain, which, in turn, is responsible for the increased activity of the catalyst. Also, the Ag/Ni samples exhibit good stability under operating conditions due to the existence of stable Ni3+ compounds on the surface.

In this work, we have synthesized inorganic-organic hybrid nanoparticles via radiation synthesis of inorganic nanoparticles (Ag and CeO2) in aqueous dispersions containing radiation-synthesized poly(N-vinyl pyrrolidone) (PVP) nanogels (NG). The experiments show that there are strong interactions between the inorganic precursors (Ag+ and Ce3+) and the nanogel prior to irradiation. The two hybrid systems (Ag/NG and CeO2/NG) were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD confirms the formation of crystalline Ag and CeO2. TEM reveals that the inorganic nanoparticles are evenly distributed in/on the nanogel. Both XRD and TEM show that size of the inorganic particles is controlled by the nanogel.

The development of Pt-free nanocatalysts with enhanced electrocatalytic activity and durability is essential for the commercialization of fuel cells. Herein, we report a new class of active and durable PdNi nanocatalysts for the oxygen reduction reaction (ORR) in an alkaline medium. PdNi nanoframework (PdNi-NF), consisting of interconnected ultrathin ridges was synthesized through a galvanic replacement reduction (GRR) strategy using Ni nanoparticles, obtained by radiolytic reduction, as seeds. PdNi nanochain (PdNi-NC), composed of aggregated nanoparticles, was produced by one-pot γ-radiation induced reduction. It was found that the carbon-supported PdNi-NF catalysts exhibit higher ORR activity and enhanced durability compared to PdNi-NC/C (PdNi-NC on carbon), Pd-NP/C (Pd nanoparticle on carbon), and commercial Pt/C catalysts. The superior activity of PdNi-NF/C catalyst may originate from the nanoframework morphology that facilitates the O2 diffusion and the electronic effect induced by the sub-surface PdNi alloy; the improved durability can be ascribed to the stable Pd-enriched surface layer. 

The role of intermediate phases in CeO2 mesocrystal formation from aqueous CeIII solutions subjected to γ-radiation was studied. Radiolytically formed hydroxyl radicals convert soluble CeIII into less soluble CeIV. Transmission electron microscopy (TEM) and X-ray diffraction studies of samples from different stages of the process allowed the identification of several stages in CeO2 mesocrystal evolution following the oxidation to CeIV: (1) formation of hydrated CeIV hydroxides, serving as intermediates in the liquid-to-solid phase transformation; (2) CeO2 primary particle growth inside the intermediate phase; (3) alignment of the primary particles into “pre-mesocrystals” and subsequently to mesocrystals, guided by confinement of the amorphous intermediate phase and accompanied by the formation of “mineral bridges”. Further alignment of the obtained mesocrystals into supracrystals occurs upon slow drying, making it possible to form complex hierarchical architectures. 

A versatile method to produce metallic nickel nanoparticles is demonstrated. Metallic Ni nanoparticles have been synthesized from aqueous solution of NiCl2 using gamma-radiation induced reduction. To prevent Ni re-oxidation, post-irradiation treatment was elaborated. Structural and compositional analyses were executed using X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. These studies reveal that the synthesized material consists of fcc Ni particles having size of 3.47 +/- 0.71 nm. The nanoparticles have a tendency to agglomerate to the larger clusters. The latter are partially oxidized to form thin amorphous/poor-crystalline Ni(OH)(2)/NiO layers at the surface. Magnetization measurements demonstrate that the nanomaterial exhibit ferromagnetic-like behaviour with magnetization 30% lower than that in bulk Ni. The large active surface area (ECSA, 39.2 m(2) g(-1)) and good electrochemical reversibility, confirmed by the electrochemical studies, make the synthesized material a potential candidate as an active component for energy storage devices.