X maxn 150 silicon drift detector

Gold disc electrodes (8 mm diameter)
were cut from a polycrystalline gold foil (0.5 mm thick, MaTecK, 99.995%)
and prepared by polishing and flame annealing according to the procedure
we have previously described.^{28 (link)} The gold
electrode cleanliness was assured by scanning electron microscopy
(SEM) performed using an Apreo SEM (ThermoFisher Scientific). Micrographs
were obtained using an acceleration voltage of 10 kV and an electron
beam current of 0.4 nA. Additionally, elemental analysis of the surface
composition was performed using energy dispersive X-ray spectrometry
(EDX) (Oxford Instruments X-Max^N 150 silicon drift detector).
The EDX data were processed using the Pathfinder X-ray Microanalysis
software v1.3. The SEM micrographs and EDX spectra are shown in Figure S1 in the Supporting Information (SI).
Establishing surface cleanliness is crucial when studying cation effects
on CO₂RR and HER, as we have previously shown that, for
instance, polishing alumina particles can contaminate the gold surface
and promote water reduction by the release of Al³⁺ ions
in an acidic electrolyte.^{28 (link)}