(471c) Ni-Fe Alloy Nanowire Arrays As Outstanding Bifunctional Electrocatalysts for Overall Water Splitting

Renewable energy driven electrocatalytic water splitting has been considered by many as the most promising green hydrogen production technology. Its high electricity consumption cost however prevents it from becoming the prevailing hydrogen production technology. Highly efficient and durable low cost electrocatalysts are the key to reduce its production cost to make it more competitive with other currently significantly cheaper hydrogen production technologies. Herein, we develop FeNi alloy nanowire arrays as outstanding bifunctional electrocatalysts for overall water splitting. The overpotentials of Ni nanowire arrays for the hydrogen evolution reaction at current densities of 20 and 400 mA/cm² are only 112 and 346 mV, respectively, and those of FeNi-nanowire arrays for the oxygen evolution reaction at current densities of 20 and 400 mA/cm² are only 249 and 326 mV, respectively. The overall water splitting is conducted by using Ni nanowire arrays as the cathode and NiFe nanowire arrays as the anode, achieving 10 mA/cm² at an ultralow potential of 1.61 V. The overall water splitting efficiency remains nearly unchanged after 24 hours operation at a high current density of 400 mA/cm². The outstanding stability and low overpotentials at high current densities demonstrates that the present electrocatalysts are promising for large scale practical applications.