In situ electrochemical surface derivation of cobalt phosphate from a Co(CO3)0.5(OH)·0.11H2O nanoarray for efficient water oxidation in neutral aqueous solutionElectronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c6nr09585b

In this Communication, cobalt phosphate (Co-Pi) has been successfully developed on a Co(CO 3 ) 0.5 (OH)·0.11H 2 O nanoarray (CCH NA) on Ti mesh in neutral phosphate-buffered solution (PBS) via in situ electrochemical surface derivation. The resulting core@shell structured CCH@Co-Pi NA/Ti exhibits remarkable activity toward water oxidation with the need of an overpotential of 460 mV to achieve a geometrical catalytic current density of 10 mA cm −2 in 0.1 M PBS, with a high turnover frequency of and long-term electrochemical stability. Cobalt phosphate developed on a Co(CO 3 ) 0.5 (OH)·0.11H 2 O nanoarray supported on Ti mesh (CCH@Co-Pi NA/Ti) is high-active and durable for water oxidation with overpotential of 460 mV for 10 mA cm −2 at pH 7.