Facile and Scalable Synthesis of Robust Ni(OH)2 Nanoplate Arrays on NiAl Foil as Hierarchical Active Scaffold for Highly Efficient Overall Water Splitting

Developing highly efficient low-cost electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte is essential to advance water electrolysis technology. Herein, Ni(OH)2 nanoplates aligned on NiAl foil (Ni(OH)2/NiAl) are developed by simply dealloying NiAl foil in KOH, which exhibits high electrocatalytic activity for OER with a small overpotential of 289 mV to achieve 10 mA cm-2 and outstanding durability with no detectable degradation during long-term operation. Furthermore, such Ni(OH)2/NiAl can effectively act as an active and robust hierarchical scaffold to simply electrodeposit other catalysts with intrinsically higher activity such as NiMo and NiFe nanoparticles for highly efficient HER and OER, respectively. The prepared NiFe/Ni(OH)2/NiAl displays superior OER catalytic activity with overpotentials of 246, 315, and 374 mV at 10, 100, and 500 mA cm-2, respectively. While NiMo/Ni(OH)2/NiAl catalyst exhibits remarkable HER performance with a small overpotential of 78 mV to deliver 10 mA cm-2. Consequently, the electrolysis device composed of the above two electrocatalysts demonstrates superb water splitting performance with a cell voltage of 1.59 V at 10 mA cm-2. These results open up opportunities to explore and optimize low-cost advanced catalysts for energy applications.