Development of cost-effective, high-performance electrocatalysts for water splitting is the key technological requirement for the hydrogen economy. Here, we report an in situ transformation approach for the preparation of a core-shell structured bifunctional electrocatalyst composed of a metallic Ni 3 Fe nanosheet-framework and a thin layer of Ni 3 Fe(OH) 9 shell on various substrates. The Ni 3 Fe alloy nanostructured framework provides large electroactive surface area and accelerates the charge transport, while the Ni 3 Fe(OH) 9 nanoshell allows an excellent electrochemical accessibility and high catalytic activity. When acting as an anode for the oxygen evolution reaction (OER), the hybrid catalyst is characterized by a low onset potential (η onset = 230 mV), small Tafel slope (28 mV/dec), and stable catalytic activity (over 24 h). More importantly, the hybrid can act as an excellent bifunctional catalyst and deliver a current density of 10 mA cm -2 at a cell voltage of 1.63 V with long stability in a symmetric alkaline electrolyzer for overall water electrolysis.
- bifunctional electrocatalyst
- core-shell structure
- in situ synthesis
- NiFe layered double hydroxide
- water electrolysis