Methods to Generate Structurally Hierarchical Architectures in Nanoporous Coinage Metals

Abstract

The fundamental essence of material design towards creating functional materials lies in bringing together the competing aspects of a large specific surface area and rapid transport pathways. The generation of structural hierarchy on distinct and well-defined length scales has successfully solved many problems in porous materials. Important applications of these hierarchical materials in the fields of catalysis and electrochemistry are briefly discussed. This review summarizes the recent advances in the strategies to create a hierarchical bicontinuous morphology in porous metals, focusing mainly on the hierarchical architectures in nanoporous gold. Starting from the traditional dealloying method and subsequently moving to other non-traditional top-down and bottom-up manufacturing processes including templating, 3D printing, and electrodeposition, this review will thoroughly examine the chemistry of creating hierarchical nanoporous gold and other coinage metals. Finally, we conclude with a discussion about the future opportunities for the advancement in the methodologies to create bimodal structures with enhanced sensitivity.

Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry

“…Structuring on multiple length scales may solve the dilemma by admitting both small pores for achieving a high specific surface area and large pores for transport. Nanoporous metals with multiple microstructural length scales have been the subject of considerable interest in recent years. − The lowest structural level of multimodal NPG is typically made by dealloying, and numerous approaches toward the higher structural levels have been proposed, such as templating, , additive manufacturing, and selective dissolution of multiphase alloys . A particularly stringent implementation of multileveled pore structures is hierarchical porous materials in which the structural organization at each of the individual hierarchy levels is geometrically similar, with identical geometry and topology at each level but distinctly different characteristic length scales.…”

“…Below, we briefly indicate how the preparation protocol of the previous sections can be expanded to yield nested-network nanoporous gold with two hierarchy levels. The making of porous metals with other, less stringent multiscale geometries is described in several recent reviews. − …”

Highly Porous 3D Gold Enhances Sensitivity of Amperometric Biosensors Based on Oxidases and CuCe Nanoparticles

“…In particular, 2D and 3D materials with extra-large areas are the promising candidates for this aim [ 1 , 17 , 18 , 19 , 20 , 21 ]. A lot of synthetic methods for obtaining 3D materials have been described [ 10 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

“…A variety of approaches to synthesize pAu have been reported in addition to methods of sputtering and self-assembling [ 17 , 27 , 41 ]. The pore size in pAu can be modulated from 5 up to 50 nm, depending on the type of synthesis protocol used [ 24 , 30 ].…”

Achieving Ultralow-Density, High-Purity Au Foam Hohlraum with Hierarchical Porous Structure

“…Firstly, the metallic mainframe provides the material with high electrical, excellent heat conductivity, and high strength [3]; additionally, the hierarchical porous structure with high porosity has an enhanced specific area to absorb more ions (or molecules) and facilitate mass transportation [5,6]. Thus, they are widely used in catalytic, electrochemical, sensor, and purification [7][8][9][10][11][12][13][14][15]. Synthesis of porous noble metal materials with multimodal structures is still challenging, although significant progress in fabricating multimodal porous ceramics, metal oxides, and organic carbon has been achieved.…”