Hierarchically Structured Nanoporous Palladium with Ordered/Disordered Channels for Ultrahigh and Fast Strain

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Metallic actuators offer a promising alternative to traditional piezoelectric ceramics and conducting polymers.
• A significant challenge remains in achieving high strain amplitudes (over 4%) coupled with rapid strain responses in metallic actuators.

Purpose of the Study:

• To fabricate a novel bulk nanoporous palladium (NP-Pd) material with a hierarchical structure.
• To investigate the potential of this material to overcome limitations in strain amplitude and response speed for metallic actuators.

Main Methods:

• Fabrication of bulk nanoporous palladium (NP-Pd) with a microsheet-array-like hierarchically nanoporous (MAHNP) structure via dealloying a eutectic Al-Pd precursor.
• Characterization of the hierarchical structure, comprising microsized channels/sheets and nanosized networks.
• Evaluation of hydrogen adsorption/desorption kinetics and strain response performance.

Main Results:

• The MAHNP structure facilitates rapid mass transport through ordered channels and provides a large surface area for hydrogen interactions via nanoligaments.
• Achieved an ultrahigh strain amplitude of 4.68%, the highest reported for bulk electrochemical metallic actuators.
• Demonstrated a fast strain rate, with a maximum value approaching 1 × 10^-4 s^-1.
• Showcased superior transport kinetics compared to unimodal NP-Pd.

Conclusions:

• The developed MAHNP-Pd material significantly advances the performance of metallic actuators, offering unprecedented strain amplitudes and fast response times.
• The hierarchical structure is key to enabling efficient mass transport and high surface area for enhanced electrochemical performance.
• This breakthrough paves the way for next-generation actuators with superior capabilities.