Self-supporting sea urchin-like Ni-Mo nano-materials as asymmetric electrodes for overall water splitting

Developing efficient and stable electrocatalysts has always been the focus of electrochemical research. Here, sea urchin-like nickel-molybdenum bimetallic phosphide nickel-molybdenum alloy (Ni₄Mo) and (Ni-Mo-P) were successfully synthesized by hydrothermal, annealing and phosphating methods on nickel foam (NF). The unusual shape of the sea urchin facilitates gas release and mass transfer and increases the interaction between catalysts and electrolytes. The Ni₄Mo/NF and Ni-Mo-P/NF electrodes only need overpotentials of 72 and 197 mV to reach 50 mA·cm⁻² under alkaline conditions for hydrogen evolution reaction and oxygen evolution reaction, respectively. The Ni₄Mo/NF and Ni-Mo-P/NF asymmetric electrodes were used as anode and cathode for the overall water splitting, respectively. In 1.0 M KOH, at a voltage of 1.485 V, the electrolytic device generated 50 mA·cm⁻² current density, maintaining for 24 h without reduction. The labor presents a simple method to synthesize a highly active, low-cost, and strongly durable self-supporting electrode for over-water splitting.