Interweaved Nickel Phosphide Sponge as an Electrode for Flexible Supercapattery and Water Splitting Applications

A unique multifunctional electrode made of well-defined highly crystalline Ni-P nanoparticles interweaved apiece to form sponge-like structure prepared by the single-step hydrothermal method. The distinct phases of interlinked nanospherical Ni-P compounds (Ni₂P, Ni₂P/Ni₁₂P₅, and Ni₁₂P₅) were obtained at 140 °C with different reaction time periods. The Ni₂P exhibits supreme specific capacity of 206 mA h g^-1 (1354 F g^-1) at 5 mA cm^-2, which seems to be the highest among the Ni₂P reported so far. Biomass-derived activated carbon was prepared as a negative electrode (135 F g^-1 at 1 mA cm^-2) to fabricate a flexible supercapattery gadget, which delivered remarkable energy density and power density of 42 W h kg^-1 and 2856 W kg^-1 respectively, at 3 mA cm^-2 even after 10000 cycles. The Ni-P coated carbon cloth has shown immense mechanical strength and durability, which was tempting to use for electrocatalytic application. Both oxygen evolution reaction and hydrogen evolution reaction trials resulted in the evolution of an enormous amount of gas bubbles with low overpotentials of 278 and 234 mV to achieve a current density of 10 mA cm^-2, respectively. Hence, the dominant Ni-P electrodes were made multifunctional by demonstrating its potential application for efficient appliances.