Formation, control and functionalization of nanoporous silver through changing dealloying media and elemental doping

Abstract

In this paper, the influence of alloy composition, dealloying solution and elemental doping on the dealloying process of rapidly solidified Mg-Ag based alloys and the formation of nanoporous silver (NPS) has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The results show that NPS and nanoporous silver-palladium (NPS-Pd) alloys can be fabricated by dealloying the Mg-Ag based alloys in acid media under free corrosion conditions. The NPS and NPS-Pd exhibit an open, three-dimensional bicontinuous interpenetrating ligament-channel structure. Furthermore, alloy composition and phase constitution of the Mg-Ag precursors have a significant influence on the ligament/channel size and the formation of cracks in NPS. The length scales of ligaments/channels in NPS can be tuned by simply changing the dealloying solution. Crack-free NPS with good mechanical integrity and small ligament/channel sizes can be obtained by dealloying the Mg-Ag alloys in suitable acid solutions. Moreover, the addition of Pd into Mg-Ag has a significant influence on the dealloying process and results in the formation of ultrafine bimodal NPS-Pd with ligaments/channels of $5 nm. The NPS-Pd alloy shows excellent hydrogen sensing properties with stable sensitivity, fast response and low detection limit. Our present findings provide implications for control and functionalization of nanoporous metals or alloys by alloy design, selection of dealloying media and elemental doping.

Using corrosion to fabricate various nanoporous metal structures

“…Besides the precursor composition, dealloying conditions such as dealloying time, temperature and solution, also have great effects on the microstructure of the nanoporous metals [19,[60][61][62][63][64]. For the dealloying time, in order to obtain complete 3D nanoporous structure, the dealloying time should be long enough to penetrate the entire precursor.…”

Characterization and Functional Applications of Nanoporous Ag Foams Prepared by Chemical Dealloying

“…With a higher porosity of the Ag foam (dealloyed from Ag 30 Al 70 ) after 3 hours, the phenylethene characteristic peak intensity is the lowest, about 5 pct, in comparison to that of the Ag foam (dealloyed from Ag 40 Al 60 ) which is about 10 pct.i Besides, Ag has been discovered as an effective antimicrobial agent. [27,28] Due to their much higher specific surface area, the Ag nanoporous foams are expected to exhibit better antimicrobial capability than that of the flat Ag thin film. Therefore, in this study, the standard antimicrobial test was performed on the Ag nanoporous foams and Ag thin film.…”

Nanoporous Metals as Novel Catalysts for Chemical Transformations☆

“…Additionally, the Al-60 at.% Ag containing single-phase Ag 2 Al alloy could not be dealloyed either in 5 wt% HCl or in 20 wt% NaOH solution even at temperature of >90 C. All AgNPores bear an open, bicontinuous ligament channel structure with length scales of 90-500 nm (Figure 4(a)). In contrast, Ji et al 9 used acid with different pKa as dealloying media and rapidly solidified Mg-Al alloys to get the 6-100 nm (in case of AgPdNPore) of ligament length. For example, rapidly solidified Mg 77 Ag 23 was treated with 5 wt% phosphoric acid for 10 min and resulted in AgNPore with length of $23 nm (Figure 4(b)).…”