Hierarchical heterogeneous NiFe-LDH/Ni/NM nanosheets grown in situ for stably overall water splitting at large current densities

Abstract

The use of non-noble metals to prepare effective and stable catalysts is an excellent technique that reduces the cost and energy consumption of hydrogen synthesis using water electrolysis. In this study, a porous Ni layer was first electrodeposited on the surface of Ni mesh (NM) as a substrate, and then Ni/NM electrodes were prepared by CV oxidation for hydrogen evolution reaction (HER); NiFe-LDH/Ni/NM electrodes were prepared by a hydrothermal approach for oxygen evolution reaction (OER). The electrode has excellent electrocatalytic performance; when the current density reaches 10 and 100 mA cm−2, the Ni/NM electrode’s HER overpotential is 65 and 178 mV, respectively; when the current density reaches 100 mA cm−2, the NiFe-LDH/Ni/NM electrode’s OER overpotential is 236 mV. As cathode and anode, when the Ni/NM || NiFe-LDH/Ni/NM electrolyzer was constructed for total water splitting in 1 M KOH, the cell voltages required 1.53 V and 1.80 V were to achieve 20 and 100 mA cm−2 current density. When simulating industrial applications at high current densities of 500 and 1000 mA cm−2, the electrolyzer retains stability for at least 154 h. This study can offer an effective strategy for the preparation of structurally stable electrocatalysts from large current water electrolysis.