Extent of Pseudocapacitance in High‐Surface Area Vanadium Nitrides

Early transition‐metal nitrides, especially vanadium nitride (VN), have shown promise for use in high energy density supercapacitors due to their high electronic conductivity, areal specific capacitance, and ability to be synthesized in high surface area form. Their further development would benefit from an understanding of their pseudocapacitive charge storage mechanism. In this paper, the extent of pseudocapacitance exhibited by vanadium nitride in aqueous electrolytes was investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The pseudocapacitance contribution to the total capacitance in the nitride material was much higher than the double‐layer capacitance and ranged from 85 % in basic electrolyte to 87 % in acidic electrolyte. The mole of electrons transferred per VN material during pseudocapacitive charge storage was also evaluated. This pseudocapacitive charge‐storage is the key component in the full utilization of the properties of early‐transition metal nitrides for high‐energy density supercapacitors.Double‐layer capacitance vs. pseudocapacitance: the electrostatic double‐layer and pseudocapacitive charge storage mechanisms in high‐surface‐area vanadium nitride are investigated. The magnitude of the pseudocapacitive charge storage capacity and mole of electrons transferred are reported. The pseudocapacitive charge‐storage mechanism is the key component in maximizing the energy density of supercapacitors based on transition‐metal nitrides.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146597/1/batt201800050.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146597/2/batt201800050_am.pd

X-ray radio-enhancement by Ti3_{3}C2_{2}Tx_{x} MXenes in soft tissue sarcoma

Radiotherapy is a cornerstone of cancer treatment. However, due to the low tissue specificity of ionizing radiation, damage to the surrounding healthy tissue of the tumor remains a significant challenge. In recent years, radio-enhancers based on inorganic nanomaterials have gained considerable interest. Beyond the widely explored metal and metal oxide nanoparticles, 2D materials, such as MXenes, could present potential benefits because of their inherently large specific surface area. In this study, we highlight the promising radio-enhancement properties of Ti$_{3}$C$_{2}$T$_{x}$ MXenes. We demonstrate that atomically thin layers of titanium carbides (Ti$_{3}$C$_{2}$T$_{x}$ MXenes) are efficiently internalized and well-tolerated by mammalian cells. Contrary to MXenes suspended in aqueous buffers, which fully oxidize within days, yielding rice-grain shaped rutile nanoparticles, the MXenes internalized by cells oxidize at a slower rate. This is consistent with cell-free experiments that have shown slower oxidation rates in cell media and lysosomal buffers compared to dispersants without antioxidants. Importantly, the MXenes exhibit robust radio-enhancement properties, with dose enhancement factors reaching up to 2.5 in human soft tissue sarcoma cells, while showing no toxicity to healthy human fibroblasts. When compared to oxidized MXenes and commercial titanium dioxide nanoparticles, the intact 2D titanium carbide flakes display superior radio-enhancement properties. In summary, our findings offer evidence for the potent radio-enhancement capabilities of Ti$_{3}$C$_{2}$T$_{x}$ MXenes, marking them as a promising candidate for enhancing radiotherapy

X-ray radio-enhancement by Ti₃C₂Tₓ MXenes in soft tissue sarcoma

Radiotherapy is a cornerstone of cancer treatment. However, due to the low tissue specificity of ionizing radiation, damage to the surrounding healthy tissue of the tumor remains a significant challenge. In recent years, radio-enhancers based on inorganic nanomaterials have gained considerable interest. Beyond the widely explored metal and metal oxide nanoparticles, 2D materials, such as MXenes, could present potential benefits because of their inherently large specific surface area. In this study, we highlight the promising radio-enhancement properties of Ti₃C₂Tₓ MXenes. We demonstrate that atomically thin layers of titanium carbides (Ti₃C₂Tₓ MXenes) are efficiently internalized and well-tolerated by mammalian cells. Contrary to MXenes suspended in aqueous buffers, which fully oxidize within days, yielding rice-grain shaped rutile nanoparticles, the MXenes internalized by cells oxidize at a slower rate. This is consistent with cell-free experiments that have shown slower oxidation rates in cell media and lysosomal buffers compared to dispersants without antioxidants. Importantly, the MXenes exhibit robust radio-enhancement properties, with dose enhancement factors reaching up to 2.5 in human soft tissue sarcoma cells, while showing no toxicity to healthy human fibroblasts. When compared to oxidized MXenes and commercial titanium dioxide nanoparticles, the intact 2D titanium carbide flakes display superior radio-enhancement properties. In summary, our findings offer evidence for the potent radio-enhancement capabilities of Ti₃C₂Tₓ MXenes, marking them as a promising candidate for enhancing radiotherapy.ISSN:2047-4830ISSN:2047-484