Enhancing the free corrosion dealloying rate with a catalytically driven reaction

Abstract

Despite its high popularity, chemical dealloying that is widely used for the fabrication of nanoporous metals is a relatively slow process: dealloying a few milligrams of bulk material may take from several hours up to a few days, depending on the material system. Raising the temperature of the corroding medium is a common approach to speed up the dealloying process. However, high temperatures cause undesired ligament growth in dealloyed materials. Here we report for the first time the use of a catalytically driven reaction to speed up the dealloying process at ambient temperature and pressure. To demonstrate the concept, we show that the free corrosion dealloying of a silver-aluminum alloy is significantly faster with the help of a platinum catalyst. More importantly, the corresponding characteristic nanostructured size is much smaller than that without a catalyst. Our finding is expected to play a central role in scaling up the dealloying process from the laboratory to the industrial scale.

pH-Controlled Dealloying Route to Hierarchical Bulk Nanoporous Zn Derived from Metastable Alloy for Hydrogen Generation by Hydrolysis of Zn in Neutral Water

“…Prior to presenting our experimental results, we will briefly clarify the basic chemistry mechanisms used for the fabrication of NP-Zn. Metallic Zn can dissolve in aqueous corroding media through the following oxidation reaction This reaction requires at least −0.76 V vs SHE and will only proceed if it is coupled to a reduction reaction that can generate the required potential accordingly to the mixed potential theory of corrosion . In nonoxidizing acidic and alkaline media, such a reduction reaction is associated with protons (H + ) or water reduction into H 2 gas through eqs and , respectively The reaction through eq or is pH-dependent as illustrated in Figure , and the generated pH-dependent voltage is given by eq In the specific situation where the pH is null, eq will generate 0.0 V vs SHE, meaning there is a very high overpotential of +0.76 V (i.e., 0.0 V minus −0.76 V) available to drive the dissolution of Zn through eq in combination with eq .…”

“…In recent years, monolithic nanoporous metals have gained increasing interest because of their broad range of potential applications. − However, much attention has been paid to the synthesis and applications of less-reactive nanoporous metals including nanoporous Au, Pd, Pt, Ag, Cu, Sn, and Ni. ,,,− Nanostructured metals made of more-reactive earth-abundant elements with standard reduction potentials (SRPs) far below the standard hydrogen electrode (SHE) are desirable in several applications. − However, the synthesis of this class of nanostructured materials is hindered by their high chemical reactivity. The dealloying strategy commonly used to produce nanoporous metals by selective alloy corrosion in aqueous media is more suitable for the fabrication of the less-reactive nanoporous metals mentioned above. , This is because the SRPs of less-reactive metals are much higher than, or close to, the SHE so that in a starting parent material, the more-reactive sacrificial metal with very negative SRP can be selectively dissolved using acidic or alkaline aqueous media, without attacking the more-noble component with a more-positive or less-negative SRP.…”

“…This reaction requires at least −0.76 V vs SHE and will only proceed if it is coupled to a reduction reaction that can generate the required potential accordingly to the mixed potential theory of corrosion. 21 In nonoxidizing acidic and alkaline media, such a reduction reaction is associated with protons (H + ) or water reduction into H 2 gas through eqs 2 and 3, respectively 33…”

Integrated Metal–Air Battery and Selective Electrolytic Leaching Cell for the Preparation of Nanoporous Metals

“…The rate of the ORR could be enhanced through nitrogen-doping of the ACC oxygen reduction catalyst . Enhancing the rate of the cathodic reduction reaction in our Ag–air battery will automatically boost the rate of Ag dissolution from the anode, as we have previously demonstrated in the case of selective removal of aluminum from silver–aluminum alloys to make nanoporous Ag (NP-Ag): Typically, a Pt catalyst was used to speed up the rate of the counter hydrogen reduction reaction associated with aluminum oxidation in nonoxidizing acids, which in turn resulted in strong enhancement of the rate of this aluminum dissolution, accordingly to the mixed potential theory of corrosion …”

Recent advances in nanoporous materials for renewable energy resources conversion into fuels

“…1b). Deng et al [122] studied the tunability of pore size using catalytically driven reaction. Hsieh et al (Reproduced from ref.…”