Connected design of Ni foam-supported porous Ni and FeOOH/porous Ni electrocatalysts for overall water splitting in alkaline media

The rational construction of advanced non-noble metal-based electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is extremely significant in promoting hydrogen energy from theory to practical application. Herein, we designed a connected preparation route to successfully construct Ni foam-supported porous nickel (labeled as Ni/NF) and FeOOH/porous nickel (labeled as FeOOH/Ni/NF) microstructures. It was found that the as-constructed Ni/NF and FeOOH/Ni/NF integral electrodes separately presented superb HER and OER electrocatalytic activities. In 1 M KOH solution, the Ni/NF and FeOOH/Ni/NF electrodes required overpotentials of 48 mV for HER and 191 mV for OER to deliver the current density of 10 mA cm−2, respectively. At the same time, the chronopotentiometry measurements showed that as-constructed Ni/NF and FeOOH/Ni/NF integral electrodes could continuously work over 180 h at 50 mA cm−2 for HER (Ni/NF) and 300 h at 100 mA cm−2 for OER (FeOOH/Ni/NF), exhibiting excellent long-term stability. In a two-electrodes system employing the Ni/NF as the cathode and the FeOOH/Ni/NF as the anode, more importantly, only a voltage of 1.49 V was required to reach the current density of 10 mA cm−2 with outstanding durability of 200 h at 50 mA cm−2 and high Faradaic efficiency. The present work provides a simple and relied technique to construct connected non-noble metal-based HER and OER electrocatalysts for practical applications.