The fabrication and surface functionalization of porous metal frameworks – a review

Abstract

Porous metal frameworks offer potentially useful applications for the aerospace, automotive and bio-medical industries. They can be used as electrodes, actuators, or as selective membrane films. The versatility of the physical features (pore size, pore depth, overall porosity and pore surface coverage) as well as the large range of surface chemistries for both metal oxides and pure noble metals offers scope to functionalise metal nano-particles and networks of nano-porous metal structures. As well as traditional routes to producing metal structures, such as metal sintering or foaming, novel high-throughput techniques have recently been investigated. Nanoparticle self-assembly, metal ion reduction and deposition as well as metal alloy de-alloying were identified as sustainable routes to produce large surface areas of such nano-porous metal frameworks. The main limitations of the current fabrication techniques include the difficulty to process stable and homogeneous arrays of nano-scale pores and the control of their morphology due to the high reactivity of nano-structured metal structures. This paper aims at critically reviewing the various fabrication techniques and surface functionalization routes used to produce advanced functional porous metal frameworks. The limitations and advantages of the different fabrication techniques will be discussed in light of the final material properties and targeted applications. Keywordsporous metal frameworks; porous metal fabrication routes; metal surface chemistry; application of metal frameworks; 3

One-pot preparation of thin nanoporous copper foils with enhanced light absorption and SERS properties

“…24 Generally, chemical or electrochemical dealloying methods are chosen to prepare various NPMFs (such as Au, Ag, Pt, and Cu) with controlled pore and ligament sizes, resulting in novel catalytic, sensing, electrical and optical properties. 22,[25][26][27][28][29] As a low-cost metal material, nanoporous Cu foams/foils have aroused much interest of researchers in various fields because of their excellent physical and chemical properties.…”

Investigation of hybrid ion-exchange membranes reinforced with non-woven metal meshes for electro-dialysis applications

“…This is a promising result as water or solvent swelling may lead to degradation of the membranes due to the osmotic swelling and volume expansion and solvent cross-over [15]. The use of metal reinforcement may therefore reduce this issue, while enhancing the electrical conductivity of the materials [26]. The IEC and water uptake results were, however, obtained by considering the total membrane mass, including that of the reinforcement metal material that is denser in the case of stainless steel compared to the previously mentioned polymer materials.…”

“…In order to tackle these issues, new materials with improved interfaces and better chemical and mechanical stabilities were developed. The development of novel highly porous electrically conductive reinforcement materials such as carbon or metal-based architectures may provide an alternative to polymeric material reinforcements and sustainable solutions to the improvement of IEMs [25,26].…”

Design of stainless steel porous surfaces by oxide reduction with hydrogen

“…Improved surface areas can enhance adhesion, heat exchange or catalytic performance among other useful properties. The methods to achieve this result are numerous [1] such as metal sintering and foaming. Exploring a new route using gaseous oxide reduction is proposed in this study.…”