The miniaturisation of technology increasingly requires the development of both new structures as well as novel techniques for their manufacture and modification. Semiconductor nanowires (NWs) are a prime example of this and as such have been the subject of intense scientific research for applications ranging from microelectronics to nano-electromechanical devices. Ion irradiation has long been a key processing step for semiconductors and the natural extension of this technique to the modification of semiconductor NWs has led to the discovery of ion beam-induced deformation effects. In this work, transmission electron microscopy with in situ ion bombardment has been used to directly observe the evolution of individual silicon and germanium NWs under irradiation. Silicon NWs were irradiated with either 6 keV neon ions or xenon ions at 5, 7 or 9.5 keV with a flux of 3 × 10 ¹³ ions cm ⁻² s ⁻¹ . Germanium NWs were irradiated with 30 or 70 keV xenon ions with a flux of 10 ¹³ ions cm ⁻² s ⁻¹ . These new results are combined with those reported in the literature in a systematic analysis using a custom implementation of the transport of ions in matter Monte Carlo computer code to facilitate a direct comparison with experimental results taking into account the wide range of experimental conditions. Across the various studies this has revealed underlying trends and forms the basis of a critical review of the various mechanisms which have been proposed to explain the deformation of semiconductor NWs under ion irradiation.

SnO₂ nanoparticles have frequently been reported as effective electrocatalysts for CO₂ electroreduction to formate. However, in the literature, there is little knowledge of SnO₂ nanoparticles that guarantee superior electrocatalytic performance. Hence, in this study, several SnO₂ nanoparticles are compared with respect to their material properties, and correlations to the electrocatalytic performance are established. For comparison, three custom-made SnO₂-electrocatalysts were prepared, reproducing frequently cited procedures in literature. Based on the comparison, it is found that hydrothermal, sol-gel, and solid-state synthesis provide quite different electrocatalysts, particularly in terms of the particle size and crystal lattice defect structure. Desirably small nanoparticles with a comparatively high number of lattice defects are found for the nanoparticles prepared by hydrothermal synthesis, which also provide the best electrocatalytic performance in terms of Faradaic efficiency for the electroreduction of CO₂ to formate. However, despite the considerably smaller surface area, the commercial reference also provides significant electrocatalytic performance, e.g., in terms of the overall produced amount of formate, which suggests a surprisingly high surface area-specific activity for this material that is low on defects. Thus, defects do not appear to be the preferred reaction site for the CO₂ electroreduction to formate on SnO₂ in this case.