Search for: All records

This study explores and presents a comprehensive understanding of the synergistic effect of in situ formed TiO2 in Ti2C MXene (TTMXene) nanomaterials to derive enhanced energy characteristics in high-performance flexible symmetric supercapacitors. The TTMXene two-dimensional (2D) (nanocomposite) materials were synthesized by a simple single-step chemical etching method. The TTMXene thus formed exhibits a layered structure with an average particle size in the range of 10−50 nm. The electrochemical studies demonstrate that the TTMXene nanocomposite exhibits a specific capacitance of 729 F g−1 at a current density of 0.5 A g−1 . This enhanced performance is due to utilizationofa highactivesurfaceareaand excellentelectronicconductivityofthe in-situ formed TiO2 in Ti2C MXene. The prototype of a flexible symmetric TTMXene supercapacitor was fabricated and characterized. The TTMXene// TTMXenedemonstratedanexcellentenergydensityof152.3Whkg−1 atapower density of 0.215 kW kg−1 and retained 88% specific capacitance after 10,000 cycles. These findings highlight that the TTMXene nanocomposites are exceptional candidates for future flexible supercapacitor devices with long-term and superior performance. 

Grain boundary (GB) structural change is commonly observed during and after stress-driven GB migration in nanocrystalline materials, but its exact atomic scale transformation has not been explored experimentally. Here, using in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations, we observed the dynamic GB structural transformation stemming from reversible facet transformation and GB dissociation during the shear-mediated migration of faceted GBs in gold nanocrystals. A reversible transformation was found to occur between (002)/(111) and Σ11(113) GB facets, accomplished by the coalescence and detachment of $\left(\overline{1}\overline{1}1\right)/\left(002\right)$-type GB steps or disconnections that mediated the GB migration. In comparison, the dissociation of (002)/(111) GB into Σ11(113) and Σ3(111) GBs occurred via the reaction of $\left(111\right)/\left(11\overline{1}\right)$-type steps that involved the emission of partial dislocations. Furthermore, these transformations were loading dependent and could be accommodated by GB junctions. This work provides atomistic insights into the dynamic structural transformation during GB migration. 

Abstract Continual progress in technologies that rely on water splitting are often hampered by the slow kinetics associated with the oxygen evolution reaction (OER). Here, we show that the efficiency of top-performing catalysts can be improved, beyond typical thermodynamic considerations, through control over reaction intermediate spin alignment during electrolysis. Spin alignment is achieved using the chiral induced spin selectivity (CISS) effect and the improvement in OER manifests as an increase in Faradaic efficiency, decrease in reaction overpotential, and change in the rate determining step for chiral nanocatalysts over compositionally analogous achiral nanocatalysts. These studies illustrate that a defined spatial orientation of the nanocatalysts is not necessary to exhibit spin selectivity and therefore represent a viable platform for employing the transformative role of chirality in other reaction pathways and processes.