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

Abstract

AbstractThe low stability of the electrocatalysts at water oxidation (WO) conditions and the use of expensive noble metals have obstructed large‐scale H2 production from water. Herein, we report the electrocatalytic WO activity of a cobalt‐containing, water‐soluble molecular WO electrocatalyst [CoII(mcbp)(OH2)] (1) [mcbp2−=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/cm2 at 1.75 V) was observed for 1 after anchoring onto PFCC, resulting in a turnover (TO) of >3.6×103 and average TOF of 0.05 s−1 at 1.55 V (pH 7) over 20 h. A total TO of >21×103 over 8 days was calculated. The electrode allowed regeneration of∼ 85 % of the WO activity electrochemically after 36 h of continuous oxygen evolution.