Nanoporous Metals with Structural Hierarchy: A Review

Abstract

Nanoporous (np) metals have generated much interest since they combine several desirable material characteristics, such as high surface area, mechanical size effects, and high conductivity. Most of the research has been focused on np Au due to its relatively straightforward synthesis, chemical stability, and many promising applications in the fields of catalysis and actuation. Other materials, such as np-Cu, Ag, and Pd have also been studied. This review discusses recent advances in the field of np metals, focusing on new research areas that implement and leverage structural hierarchy while using np metals as their base structural constituents. First, we focus on single-element porous metals that are made of np metals at the fundamental level, but synthesized with additional levels of porosity. Second, we discuss the fabrication of composite structures, which use auxiliary materials to enhance the properties of np metals. Important applications of these hierarchical materials, especially in the fields of catalysis and electrochemistry, are also reviewed. Finally, we conclude with a discussion about future opportunities for the advancement and application of np metals.

Efficient Electrochemical Hydrogenation of 5‐Hydroxymethylfurfural to 2,5‐Bis(hydroxymethyl)furan on Ag‐Displaced Nanotextured Cu Catalysts

“…The development of novel electrode materials with nanoscale structures has been recognized to be an important strategy to enhance the catalytic activities of electrodes. Some nanoscale‐structured metals, such as nanoporous metals, have distinct electrical and electrocatalytic properties, which endow them with promising applications in a wide variety of research fields, including catalysts, sensors, batteries, supercapacitors, and fuel cells . Among various techniques used to fabricate nanoporous metals, dealloying is the most used, owing to its simplicity and high efficiency .…”

“…Some nanoscale-structured metals, such as nanoporous metals, have distinct electrical and electrocatalytic properties, which endow them with promising applications in a wide variety of research fields, including catalysts, sensors, batteries, supercapacitors, and fuel cells. [24][25][26][27][28][29][30][31] Among various techniques used to fabricate nanoporous metals, dealloying is the most used, owing to its simplicity and high efficiency. [27,29] Dealloying refers to the selective dissolution of the active metal components from an alloy through chemical or electrochemical etching to produce a residual nanoporous structure.…”

Dealloyed nanoporous materials with interface-controlled behavior

“…33 , 47 -51 There is also emerging interest in controlling dealloying protocols in order to evolve hierarchical porous microstructures. 52 This issue of MRS Bulletin provides insights into the current state of the art in a fi eld of research that is active and that has the potential to provide an array of positive surprises in the future.…”

Functionalisation of metal–polymer-nanocomposites: Chemoelectromechanical coupling and charge carrier transport

“…However, the results also prove that not only interface area plays a significant role in the actuation behaviour but also geometrical factors such as pore channel diameters, where larger diameters reduce the specific interface area but improve ion transport and electric field distribution. From this point of view, hierarchical nanoporous structures [21,22,45] seem especially promising.…”

“…actuation [21,22]. Furthermore, actuation in polypyrrole and other conjugated polymers strongly depends on the mobilities of the ions, to the extent that with different ions the same applied potential can result in either shrinking or expansion of the polymer [17].…”