Ultrafast, scalable and green synthesis of amorphous iron-nickel based durable water oxidation electrode with very high intrinsic activity via potential pulses

Electrochemical water splitting to produce clean hydrogen fuel provides a route to store electrical energy based on intermittent renewable energy sources. Oxygen evolution reaction (OER) is an essential reaction in water splitting process and requires efficient electrocatalyst to lower the overpotential. However, current electro-catalysts are limited by the complicated synthetic protocols, especially long synthesis time, along with poor intrinsic catalytic activity. Here we report a low-cost and scalable electrochemical method to synthesize efficient water oxidation electrode via potential pulses. In a two-electrode setup, two water oxidation electrodes are synthesized in merely 10 s. These two electrodes need overpotentials of 240.7 +/- 6.8 mV and 239.5 +/- 3.4 mV to catalyze OER at 10 mA/cm(2) current density normalized by geometric area. Remarkably, when normalized by electrochemically active surface area, the intrinsic catalytic activity outperformed the state-of-the-art catalysts. And the electrode is durable to catalyze OER at 100 mA/cm(2), even after repeated ultrasonication treatment, the overpotential only shift 25-51 mV. We postulate that the highly disordered defective sites of nickel hydroxide modified with iron species are the most active OER catalytic sites. In addition, the attempt to synthesize 10 water oxidation electrodes using this concept is very successful, further reducing the cycle time to 1 s per electrode. The super facile synthesis procedures, as well as the excellent catalytic performance make these materials highly suitable for large scale applications.