Environmentally Friendly Carbon‐Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts

Abstract

The dissolution of noble-metal catalysts under mild and carbon-preserving conditions offers the possibility of in situ regeneration of the catalyst nanoparticles in fuel cells or other applications. Here, we report on the complete dissolution of the fuel cell catalyst, platinum nanoparticles, under very mild conditions at room temperature in 0.1 M HClO4 and 0.1 M HCl by electrochemical potential cycling between 0.5-1.1 V at a scan rate of 50 mV s(-1) . Dissolution rates as high as 22.5 μg cm(-2) per cycle were achieved, which ensured a relatively short dissolution timescale of 3-5 h for a Pt loading of 0.35 mg cm(-2) on carbon. The influence of chloride ions and oxygen in the electrolyte on the dissolution was investigated, and a dissolution mechanism is proposed on the basis of the experimental observations and available literature results. During the dissolution process, the corrosion of the carbon support was minimal, as observed by X-ray photoelectron spectroscopy (XPS).

Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution

“…Interestingly, a recent work by Lutsuzbaia et al 33. also utilizes the concept of Pt transient dissolution for recycling platinum from PEM fuel cells.…”

Environmentally and Industrially Friendly Recycling of Platinum Nanoparticles Through Electrochemical Dissolution–Electrodeposition in Acid‐Free/Dilute Acidic Electrolytes

“…Owing to their high surface‐to‐volume ratio, PGM nanoparticles exhibit a higher activity compared to their bulk counterparts. This enables the recovery of nanoparticulate spent catalysts through electrochemical dissolution under mild conditions (dilute acidic/acid‐free baths; ambient temperature and pressure) …”

Sustainable Platinum Recycling through Electrochemical Dissolution of Platinum Nanoparticles from Fuel Cell Electrodes

“…Dissolution of Pt in presence of Cl − may take place at comparatively lower potentials through Equations (2) and (3). The potential vs. pH diagram in presence of Cl − suggests the dissolution potential to be independent for a broad range of pH between 0 and ∼6 . Figure a shows a comparison of the %dissolution values in 0.1 M and 1 M HCl electrolytes, exhibiting a clear enhancement of dissolution rate with the HCl concentration.…”

“…This is due to the fact that the dissolution potentials remain constant for pH below ∼6 in Cl − containing electrolytes, and the dissolution takes place through Equations (2) and (3). However, for pH >6, the dissolution takes place through formation of Pt(OH) 2 rather than through the [PtCl x ] 2− complexes . UV‐vis spectrum of the dissolved Pt species in 0.5 M NaCl (pH 7) through 50 cycles between 0.4 and 1.6 V at a scan rate of 100 mV/s is shown in Figure S3 (supporting information S4).…”