Figure 5. Continuous wave X-band EPR spectra for Na₂CoP₂O₇ and Li₂CoP₂O₇ on bulk electrolysis.

(a) EPR spectra for Na₂CoP₂O₇ at 0.8 V for 30 min (black), 1.2 V for 30 min (green) and 1.4 V for 300 min (blue). Only Co(II) signals at g_eff≈5 appeared on bulk electrolysis. Here, the signal at g=2 is originated from carbon. (b) EPR spectra for Li₂CoP₂O₇ at 0.8 V for 30 min (black), 1.2 V for 30 min (green), 1.4 V for 30 min (orange) and 1.4 V for 300 min (blue). Contrary to Na₂CoP₂O₇, a decrease in Co(II) signals with a concurrent increase in Co(IV) signals (g_eff≈2.3) was observed with the increase in applied voltage and time.