Potassium hydroxide solution

A two compartment polytetrafluoroethylene cell with three electrodes was used for ATR-SEIRAS measurements. The schematic of the cell and steps to prepare chemically deposited gold film on the silicon ATR crystals can be found in our previous study (35 (link)). The working electrode was the bimetallic catalyst drop casted on the gold film on the silicon ATR crystals with catalyst loading of 0.4 to 0.5 mg cm⁻². The catalyst inks were prepared by dissolving 5 mg of catalyst in 1 μl of Nafion solution (5 wt % in 50/50 water and isopropanol) and 250 μl of isopropanol. A graphite counter electrode was placed in one compartment, and a working electrode and Ag/AgCl reference electrode (3.0 M NaCl, BASi) were placed in the other compartment with gas inlet and purge lines. Two compartments were separated by a Nafion ion exchange membrane (Nafion 211, Fuel Cell Store). Potassium hydroxide solution (0.1 M; Sigma-Aldrich; 99.99%) was used as the electrolyte. The electrodes were connected to a potentiostat (Solartron 1260/1287) to apply potentials during measurements. The cell is integrated into the Agilent Technologies Cary 660 FTIR spectrometer equipped with a liquid nitrogen–cooled mercury-cadmium-telluride detector. All spectra were collected with 64 coadded scans and 4 cm⁻¹ resolutions.