2.1. Materials
The Ni foams with different pore sizes (35, 75, and 110 PPI) were
purchased from Kunshan Ansu Electronic Materials Business.
CoCl2ยท6H2O, NaBH4, KOH,
NaOH, acetone, and HCl were purchased from Chron
Chemicals (Chengdu, China). All reagents used in experiments are
analytical grade and used as received without further purification. All
deionized water (DI) is treated with nitrogen to remove dissolved oxygen
prior to use.