Cobalt Electrocatalyst on Fluorine Doped Carbon Cloth - a Robust and Partially Regenerable Anode for Water Oxidation

The low stability of the electrocatalysts at water oxidation (WO) conditions and the use of expensive noble metals have obstructed large-scale H-2 production from water. Herein, we report the electrocatalytic WO activity of a cobalt-containing, water-soluble molecular WO electrocatalyst [Co-II(mcbp)(OH2)] (1) [mcbp(2-)=2,6-bis(1-methyl-4-(carboxylate)benzimidazol-2-yl)pyridine] in homogeneous conditions (overpotential of 510 mV at pH 7 phosphate buffer) and after anchoring it on pyridine-modified fluorine-doped carbon cloth (PFCC). The formation of cobalt phosphate was identified only after 4 h continuous oxygen evolution in homogeneous conditions. Interestingly, a significant enhancement of the stability and WO activity (current density of 5.4 mA/cm(2) at 1.75 V) was observed for 1 after anchoring onto PFCC, resulting in a turnover (TO) of >3.6x10(3) and average TOF of 0.05 s(-1) at 1.55 V (pH 7) over 20 h. A total TO of >21x10(3) over 8 days was calculated. The electrode allowed regeneration of similar to 85 % of the WO activity electrochemically after 36 h of continuous oxygen evolution.