Constructing a NiCu/C/NiCu Interface for Alkaline Saline Water Electrolysis

Interface engineering is a useful way to fabricate nonprecious-based electrocatalyst materials for easy overall water splitting (OWS), which is of great importance for renewable hydrogen energy production. Herein, we designed a needle-like catalyst by a low-temperature CVD method using NiCu alloy nanoparticles evenly embedded in the graphene shell, resulting in a large-scale NiCu/C/NiCu interface. The few-layer graphene prevents the NiCu alloy nanoparticles from melting and growing and increases the number of interfaces. Meanwhile, the C layer coated on the surface of the NiCu alloy hinders the erosion of Cl- to the catalyst, showing excellent stability in the overall water splitting. The HER and OER overpotentials of the needle-like catalyst in a 1 M KOH solution were 53.8 and 298.5 mV (10 mA cm-2), respectively, and the HER and OER overpotentials in a 1 M KOH+0.5 M NaCl solution were 38.4 and 304.1 mV (10 mA cm-2), respectively. Assembled with two electrodes in a cell for saline water splitting, it reaches the current density of 100 mA cm-2 at an operating voltage of 1.86 V. Additionally, it also shows superb stability for 65 h at a high current density.