Fast electrodeposited nickle-iron hydroxide nanosheets on sintered stainless steel felt as bifunctional electrocatalyts for overall water splitting

Hydrogen fuel provided by water splitting reaction for storing intermittent renewable energy is an important topic, and electrocatalysis has been a research hot spot. Herein, we report the synthesis of an efficient bifunctional electrocatalytic electrode of nanoporous nickel-iron hydroxides coupled with a small amount of metal Ni/Fe based on stainless steel fiber felt (SSF) by a simple electrodeposition method. The prepared catalysis electrode can significantly improve the overall water splitting performance. The gaps of SSF are filled with nickel-iron hydroxide composites of which conductivity is improved by metal Ni/Fe simultaneously generated through electrodeposition. The synthesized electrode exhibits excellent electrocatalytic performance toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), only requiring overpotentials of 100 mV for HER and 210 mV for OER at 10 mA cm-2 in 1 M KOH. Employed as both anode and cathode for full water splitting, the obtained electrode also exhibits excellent activity, achieving an overall cell voltage of 1.80 V to attain 100 mA cm-2. There is almost no potential drop after a long-time durability test. Electrocatalysis studies show the enhancement of water splitting activity may be caused by the synergistic action between the NiFe(OH)x nanosheets and SSF substrate, which benefits the chemisorption of oxygen and hydrogencontaining intermediates. The excellent activity and good stability would hopefully enable the prepared electrocatalyst to mitigate the main drawbacks of existing electrolysis technologies and provide possibilities of developing next-generation water splitting technologies.