Manipulating the Corrosion Resistance of SnO₂ Aerogels through Doping for Efficient and Durable Oxygen Evolution Reaction Electrocatalysis in Acidic Media

Abstract

Implementing iridium oxide (IrO x) nanocatalysts can be a major breakthrough for oxygen evolution reaction (OER), the limiting reaction in polymer electrolyte membrane water electrolyser devices. However, this strategy requires developing a support that is electronically conductive, is stable in OER conditions, and features a large specific surface area and a porosity adapted to gas-liquid flows. To address these challenges, we synthesized IrO x nanoparticles, supported them onto doped SnO 2 aerogels (IrO x /doped SnO 2), and assessed their electrocatalytic activity towards the OER and their resistance to corrosion in acidic media by means of a flow cell connected to an inductively-coupled mass spectrometer (FC-ICP-MS). The FC-ICP-MS results show that the long-term OER activity of IrO x /doped SnO 2 aerogels is controlled by the resistance to corrosion of the doping element, and by its concentration in the host SnO 2 matrix. In particular, we provide quantitative evidence that Sb-doped SnO 2 type supports continuously dissolve while Tadoped or Nb-doped SnO 2 supports with appropriate doping concentrations are stable under acidic OER conditions. These results shed fundamental light on the complex

Oxygen Evolution Reaction Activity and Stability Benchmarks for Supported and Unsupported IrOx Electrocatalysts

“…As shown by Claudel et al, 15 this trend persists over time: IrOx nanoparticles supported onto ATO are less oxidized than IrOx nanoparticles arising from the same colloidal solution but supported on Vulcan XC72, even after 30,000 potential cycles between 1.2 and 1.6 V vs. RHE. Similar effect was recently reported for TaTO supports by Abbou et al 16 . The authors also evidenced an effect of the concentration of Ta on the oxidation degree of Ir surface atoms and of the age of the catalytic suspension.…”

“…This result implies that, the mass of Ir introduced at the PEMWE anode could be reduced by a factor of 6 for the same lifespan (investment cost) or that it could significantly decrease the electrical consumption for the same Ir loading (operational cost). 16 and Figure S12), and demonstrate that ATO-10 (both in AG and NF forms), high-surface area carbon blacks and TaTO-18 are unstable in OER conditions. In agreement with the TEM micrographs displayed in Figure 3, the drop of the OER performance is likely due to the rapid detachment of IrOx NPs from their supports, leading to a loss of electrochemically active surface area, and thus a rapid increase in the OER overpotential up to the cut-off voltage.…”

“…and IrOx/C), confirming that carbon supports corrode in OER conditions. 16 The detachment of IrOx NPs was less pronounced from doped SnO2 supports, whatever their morphology (AG or NFs). However, former in situ ICP-MS results have shown that both Sn and the doping element leach out from doped SnO2 supports in OER conditions.…”

“…Former studies have established that mixed Ir oxidation states coexist in IrOx NPs produced by the polyol route [15][16][17][18] . Moreover, the oxidation degree of the Ir surface atoms strongly depends on the chemical nature of the support [15][16]18 . Oh et al 18 first reported that IrOx nanoparticles are, in average, more metallic when supported on ATO vs. Vulcan XC72.…”

“…The instability of ATO supports in high potential conditions has been ascribed to the preferential leaching of Sb atoms segregated at their surface. 16,32,[44][45][46][47] .…”