Fig. 3.
Effect of the buffer anion on WOC onset potential and comparison of several cationic cobalt porphyrin WOC catalysts. (A) CVs of 1 mM Co-TDMImP in phthalate (black), bicarbonate (red), Na–Pi (blue), n-butylphosphonate (purple), and tert-butylphosphonate (green) buffers. The solid and dashed lines represent forward and backward scans, respectively. (A, Inset) Plot of the potential measured at –50 μA as a function of pKa of the buffer species. The red line represents the best linear fit with a slope of –54 mV.pKa–1. (B) CVs of 1 mM Co-TDMImP (black), Co-TM4PyP (red), and Co-TTMAP (blue). (B, Inset) Amplified CVs (dashed lines) and SWVs (solid lines) of Co-TM4PyP (red) and Co-TTMAP (blue) showing the 600–1,400 mV range. Other conditions include room temperature, scan rate 100 mV⋅s−1, and pH 7.