Facile Synthesis of N and P Co-Doped NiMoO 4 Hollow Nanowires and Electrochemical Deposition of NiFe-Layered Double Hydroxide for Boosting Overall Seawater Splitting

Abstract

NiMoO 4 (NM) nanowires coated on nickel foam (NF) were prepared by the facile hydrothermal method. After calcination at low temperature, the nitrogen and phosphorus were co-doped into bimetal NF@NM nanowires. The hollow nanowire structure could be obtained after low-temperature calcination and nonmetallic doping. The as-synthesized hollow NF@NiMoO 4 /N/P (NF@NM-NP) nanowires exhibit excellent hydrogen evolution reaction performance (with an overpotential of −164 mV at −100 mA cm −2 ) due to the existence of planar defects and the hollow structure. To further improve the catalytic activity in the oxygen evolution reaction, amorphous lamellar NiFe-layered double hydroxide (NiFe LDH) was deposited onto the NF@NM-NP nanowires via an electrochemical method to form core–shell NF@NM-NP@NiFe LDH, which deliver an overpotential of 218 mV at 100 mA cm −2 . Furthermore, an asymmetric setup composed of NF@NM-NP hollow nanowires and core–shell NF@NM-NP@NiFe LDH electrode were fabricated for overall seawater splitting, which can deliver potentials of 1.46 and 1.70 V at current densities of 10 and 100 mA cm −2 in simulated alkaline seawater (1 M KOH and 0.5 M NaCl), respectively. This may provide an effective path for the formation of a green energy conversion system.