A cobalt-borate nanosheet array: an efficient and durable non-noble-metal electrocatalyst for water oxidation at near neutral pH

Exploitation of efficient water oxidation electrocatalysts under benign conditions is of great importance but remains a huge challenge. In this communication, we report the preparation of a cobalt-borate nanosheet array on a Ti mesh (Co-Bi/Ti) successfully converted from an electrodeposited alpha-Co(OH)(2) nanosheet array in potassium borate (K-Bi) via in situ electrochemical tuning. The Co-Bi/Ti shows high electrocatalytic activity toward water oxidation with an overpotential of 469 mV to achieve a current density of 10mA cm (2) in 0.1 M K-Bi, with long-term electrochemical stability with a turnover frequency of 0.15 s(-1) at an overpotential of 600 mV.