Three-dimensional NiFe layered double hydroxide nanowire/ nanoporous Ni/nickel foam for efficient oxygen evolution

Abstract

NiFe layered double hydroxides (NiFe-LDHs) are considered as a promising substitute for noble metal electrocatalysts for oxygen evolution reactions (OER). A three-dimensional NiFe layered double hydroxides nanowire/nanoporous Ni interlayer/nickel foam substrate (NiFe-LDH/Ni/NF) electrocatalyst was designed and prepared on NF by a polystyrene (PS) microsphere template and a two-step in situ electrodeposition method. The electrocatalysts had a high specific surface area, an increased number of electrocatalytic active sites and improved electrochemical stability. In NiFe-LDHs/Ni/NF, the nickel nanoporous interlayer bonded closely with the NF matrix and simultaneously became loaded with the NiFe-LDH nanowires, which accelerated the electron transfer of the electrocatalyst nanowires to the matrix, increased the apparent active area, and promoted the OER. As expected, with a current density of 10 mA cm−2, NiFe-LDHs/Ni/NF exhibited a smaller overpotential of 247 mV, a smaller Tafel slope of 35.52 mV dec−1 and better durability than those of Ni/NF or NiFe-LDHs/NF. In addition, the overall water splitting system with the anode of NiFe-LDHs/Ni/NF and the cathode of Ni/NF had a small potential of 1.55 V with a current density of 10 mA cm−2.