Amorphous NiFe Nanotube Arrays Bifunctional Electrocatalysts for Efficient Electrochemical Overall Water Splitting

It is still a challenge for design and fabrication of cost-effective and efficient bifunctional electrocatalysts for both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) for overall water splitting. Herein, we design and synthesize amorphous NiFe nanotube arrays on nickel foam (NiFe NTAs-NF) with high electrocatalytic activity and excellent durability for both OER and HER in overall water splitting. The as-synthesized NiFe NTAs-NF only requires relatively low overpotentials of 216 mV for the OER and 181 mV for the HER to reach current densities of 50 and 10 mA cm–2, respectively. Moreover, when used as bifunctional catalysts for water splitting, the designed electrode only needs a low cell voltage of 1.62 V to obtain 10 mA cm–2 for the overall water splitting, with an extremely excellent durability. The excellent performance of the NiFe NTAs-NF might be attributed to the synergistic effect and amorphous phase of NiFe alloy as well as the well-defined nanotube array architecture with large surface area, abundant active sites, and sufficient gas and electrolyte diffusion channels.