While nanostructured alloy-type anodes are considered potential high-capacity alternatives to intercalation-type graphite anodes, large volume changes inherent to alloy-type anode cycling result in...

Insights into the Degradation Mechanism of Nanoporous Alloy-Type Li-Ion Battery Anodes

Time-dependent power law function for the post-dealloying chemical coarsening of nanoporous gold derived using small-angle X-ray scattering

Chelation-mediated synthesis of nanoporous gold at near-neutral pH and room temperature by free corrosion dealloying of gold-copper alloy driven by oxygen reduction

Electrochemical dealloying has become a standard technique to produce nanoporous network structures of various noble metals, exploiting the selective dissolution of one component from an alloy. While achieving nanoporosity during dealloying has been intensively studied for the prime example of nanoporous Au from a AgAu alloy, dealloying from other noble-metal alloys has been rarely investigated in the scientific literature. Here, we study the evolution of nanoporosity in the electrochemical dealloying process for both CoPd and AgAu alloys using a combination of in situ grazing-incidence small-angle X-ray scattering (GISAXS), kinetic Monte Carlo (KMC) simulations, and scanning transmission electron microscopy (STEM). When comparing dealloying kinetics, we find a more rapid progression of the dealloying front for CoPd and also a considerably slower coarsening of the nanoporous structure for Pd in relation to Au. We argue that our findings are natural consequences of the effectively higher dealloying potential and the higher interatomic binding energy for the CoPd alloy. Our results corroborate the understanding of electrochemical dealloying on the basis of two rate equations for dissolution and surface diffusion and suggest the general applicability of this dealloying mechanism to binary alloys. The present study contributes to the future tailoring of structural size in nanoporous metals for improved chemical surface activity.

https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.1c09592

In Situ Study of Nanoporosity Evolution during Dealloying AgAu and CoPd by Grazing-Incidence Small-Angle X-ray Scattering

The development of three-dimensional aperiodic energy storage devices is in part impeded by the lack of appropriate aperiodic templates that can withstand the thermal conditions required to deposit energy storage materials within their void space. Herein, the feasibility of an aperiodic three-dimensional architecture for energy storage is demonstrated for the first time by constructing a tricontinuous conductor-insulator-conductor (CIC) nanocapacitor on an aperiodic nanoporous gold scaffold. To accomplish this, the scaffold was characterized using in situ small-angle X-ray scattering (SAXS) during exposure to a thermal environment, revealing that its microstructure eventually stabilizes after undergoing a phase of rapid coarsening, indicating a departure from the 1/4 time-dependent power-law coarsening behavior usually observed at the early stage of the coarsening process. Using this stability regime, we created the CIC by intentionally precoarsening and stabilizing the scaffold before depositing two dissimilar metal oxide films in its void space by atomic layer deposition. Current-voltage characteristics and electrochemical impedance spectroscopy measurements revealed that the un-optimized 3D CIC outperformed its 2D counterpart by ∼4× in terms of capacitance. This proof-of-concept device will pave the way to the development of aperiodic three-dimensional energy storage systems with enhanced energy and power densities.

Using X-Ray Scattering to Elucidate the Microstructural Instability of 3D Bicontinuous Nanoporous Metal Scaffolds for Use in an Aperiodic 3D Tricontinuous Conductor-Insulator-Conductor Nanocapacitor.

Sven van der Meer

Papers

Using X-Ray Scattering to Elucidate the Microstructural Instability of 3D Bicontinuous Nanoporous Metal Scaffolds for Use in an Aperiodic 3D Tricontinuous Conductor-Insulator-Conductor Nanocapacitor.