Facile Synthesis of N and P Co-Doped NiMoO4 Hollow Nanowires and Electrochemical Deposition of NiFe-Layered Double Hydroxide for Boosting Overall Seawater Splitting

Abstract

NiMoO4 (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@NiMoO4/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.