Iridium-incorporated cobalt nanofibers as efficient and robust bifunctional catalysts for high-performance water electrolysis

Iridium (Ir)-incorporated cobalt (Co) nanofibers (Co-Ir-600) are fabricated via an electrospinning-calcination-in situ H2 reduction-galvanic replacement process. Benefitting from the unique one-dimensional nanofibrous heterostructure that allows rapid electron/mass transfer as well as the synergy between Ir and Co components, the Co-Ir catalyst shows a remarkable electrocatalytic activity for oxygen evolution reaction (OER) with an extremely low overpotential of 169 mV at 10 mA cm−2 in an alkaline electrolyte. Furthermore, the catalyst also presents a high hydrogen evolution reaction (HER) performance. Therefore, an alkaline electrolyzer is constructed with the Co-Ir-600 nanofibrous catalyst as both the anode and cathode electrodes, and only a small cell voltage of 1.51 V is needed to achieve 10 mA cm−2 with outstanding durability. This performance is superior to that of benchmark Pt/C∥IrO2 electrodes and many other reported water electrolysis cells. This study supplies a general and efficient way to prepare cost-effective and high-performance metal-based overall water splitting electrocatalysts.