Synergism of NiFe layered double hydroxides/phosphides and Co-NC nanorods array for efficient electrocatalytic water splitting

The green hydrogen route provides a reliable way to reduce dependence on fossil fuels. Hydrogen production by water electrolysis is an efficient way to convert unstable renewable energy sources into hydrogen energy. Herein, a rod-like N-doped carbon nanorods array cooperated with layered double hydroxide (Ni2Fe@Co-NC/CC) and a tri-metal phosphides composite (P-Ni2Fe@Co-NC/CC) is fabricated, which is believed can facilitate the electron and mass transfer efficiency. The Co element in Ni2Fe@Co-NC/CC can promote the formation of high-valence Ni and activate lattice oxygen to form abundant dual OER active sites. While the P-Ni2Fe@Co-NC/CC can obtain optimized hydrogen adsorption free energy due to synergistic effect of trimetallic phosphides and nitrogen-doped carbon structure to promotes the HER progress. Therefore, due to the synergistic effect between metal hydroxide/phosphide and Co-decorated NC nanorods array, low overpotentials of 240 and 137 mV at 100 mA cm-2 can be achieved for OER and HER with excellent electrocatalytic stability. Besides, the Ni2Fe@Co-NC/CC//PNi2Fe@Co-NC/CC device can afford cell voltage of 1.579 V at 50 mA cm-2 in water splitting, which demonstrate a new idea for rational designed electrocatalytic water splitting composites towards high activity and stability.

Automated summary

Green hydrogen is produced through water electrolysis, providing a reliable alternative to fossil fuels. A composite material consisting of N-doped carbon nanorods array, layered double hydroxide (Ni2Fe@Co-NC/CC), and a tri-metal phosphides composite (P-Ni2Fe@Co-NC/CC) is fabricated to improve the efficiency of electron and mass transfer. The Co element in Ni2Fe@Co-NC/CC promotes the formation of high-valence Ni and increases the active sites for oxygen evolution reaction (OER), while the P-Ni2Fe@Co-NC/CC enhances the hydrogen evolution reaction (HER) due to the synergistic effect of trimetallic phosphides and nitrogen-doped carbon structure. The composite material exhibits low overpotentials for OER and HER, as well as excellent electrocatalytic stability.