Highly Active 3D-Nanoarray-Supported Oxygen-Evolving Electrode Generated From Cobalt-Phytate Nanoplates

We develop a 3D nanowires-array-support/active cobalt plating to grow cobalt-phytate nanoplates (3D-NA/Co/CoNPAs) as an advanced oxygen-evolving electrode. The constructed structure exhibits greatly enhanced catalytic activity (ηj=10 mA cm–2 = 265 mV) and good stability (current retention >94% after electrolysis of 6 h). Moreover, the Co-phytate grown on 3D-NA/Co is also used as the anode in a two-electrode configured alkaline electrolyzer with the sharp decline of energy consumption (41.55 KWh kg–1Hydrogen) for hydrogen production. We then determine the insight of the electrocatalytic process toward water oxidation on our prepared electrode. First, the results reveal that the 3D-substrate can obviously reduce the resistance for the electron transfer during the oxygen evolution turnover. In addition, the introduction of active cobalt plating will lead to the self-supported Co-phytate nanostructures generation, which can significantly enlarge the electrochemically active surface area (EASA). Further, the electrode after catalysis is also characterized, and we find that the nanostructured cobalt oxo/hydroxide are densely grown on the original Co-phytate nanoplates. These core/shell nanocomposites not only own higher EASA but also obviously decrease the free-energy change during the O–O formation of the CoO6-based intermediate affected by the phytate group.