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.

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To improve the electrolysis efficiency of overall water splitting, designing an efficient and stable catalyst becomes very essential. Herein, a one-step cyclic voltammetric electrodeposition method was adopted to synthesize a lowcrystallinity NiFeCoPi/P catalyst by adding Fe and Co to NiPi/P. The synthesized NiFeCoPi/P catalyst exhibits good catalytic performance for hydrogen evolution reaction (HER) in 1 M NaOH and oxygen evolution reaction (OER) in 0.5 M Na 2 CO 3 /NaHCO 3 , showing low overpotentials of 98 and 299 mV for HER and OER at 10 mA cm −2 , respectively. Also, the electrodeposition only requires a cell voltage of 1.63 V for overall water splitting. It could be found that the introduction of Fe and Co can enhance charge transport among the metals and can effectively change the morphology of the catalyst, thus increasing the electrocatalytic performance for HER and OER. Moreover, the NiFeCoPi/P catalyst reveals good stability in the electrolysis process of overall water splitting.

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Stainless steel fiber felt was modified to prepare an OER catalyst with high electrocatalytic activity via a simple oxidation method.