NPSV was performed using a previously reported OTTLE cell33 (link) with a 12.5 μm path length over a nanocrystalline boron-doped diamond (BDD) film on a silicon substrate as a working electrode33 (link)–35 and BaF2 back window at 10 °C. Coiled platinum wire was used as the counter electrode, and Ag/AgCl in saturated KCl was used as a reference electrode. Reduction and oxidation profiles were measured against Er of +0.5 and −0.5 V, respectively, using a potential step of 0.05 V. Potential was applied using a computer-controlled potentiostat (model CHI1202b, CH Instruments). The applied potential range varied between samples as indicated. Potential step durations were 150, 300, or 600 s as noted. Spectra were integrated during the final 90 s (for 150 s steps) or 120 s (for 300 and 600 s steps).
Fourier transform infrared (FT-IR) spectroscopy was performed using an Equinox 55/S spectrometer (Bruker). The OTTLE cell was placed in a sample compartment purged with nitrogen gas. A nitrogen stream was chilled in an ethanol/dry ice bath and reheated by a resistive wire heater controlled by a model 340 temperature controller (Lake Shore Cryotronics) to maintain the temperature at 10.0(1) °C throughout the measurement.
Fourier transform infrared (FT-IR) spectroscopy was performed using an Equinox 55/S spectrometer (Bruker). The OTTLE cell was placed in a sample compartment purged with nitrogen gas. A nitrogen stream was chilled in an ethanol/dry ice bath and reheated by a resistive wire heater controlled by a model 340 temperature controller (Lake Shore Cryotronics) to maintain the temperature at 10.0(1) °C throughout the measurement.