• Andersen, Shuang Ma
• Morgen, Per

Abstract

<p>High industrial demand and limited global abundance of precious metals (PMs) make their recycling essential for industrial and societal sustainability. Owing to their high surface-to-volume ratio, recycling of nanoparticulate precious metals through dissolution in dilute acids at room temperature is quite relevant. However, their dissolution by approaches such as the cyclic oxidation-reduction of metal surfaces through surface potential manipulation may not be suitable for large-scale production. Here, we demonstrate fast dissolution of Pt-nanoparticles under mild conditions (normal temperature and pressure) in Cl- containing dilute acidic/neutral baths without using cyclic oxidation-reduction. We demonstrate that the dissolution of Pt nanoparticles through [PtClx]2- complexing is hindered by blockage of the Pt surface due to adsorption of non-oxide species (impurities), a phenomenon termed herein as non-oxide passivation (NOP). The nanoparticles can be kept active for the [PtClx]2- complexing through removal of the adsorbed species by surface activation, a process to remove the NOP layer by application of cyclic/continuous perturbation. As an example, average % dissolution rate (calculated on initial Pt loading) increases from ∼10% per h (∼30% dissolution in 3 h) for dissolution without NOP removal to ∼19% per h (∼55% dissolution in 3 h) for dissolution through cyclic activation of the Pt surface by HCl-water cycling. The approach may be implemented with a range of cost-efficient and non-toxic reagents for industrial-scale and environmentally friendly recycling of Pt.</p>

Topics

• nanoparticle
• impedance spectroscopy
• surface
• Platinum
• activation