Ultrafast Electrodeposition of Ni−Fe Hydroxide Nanosheets on Nickel Foam as Oxygen Evolution Anode for Energy‐Saving Electrolysis of Na2CO3/NaHCO3

Abstract Nickel/iron (Ni−Fe)‐based compounds are known as active electrocatalysts for the oxygen evolution reaction (OER), which plays an important role in metal−air batteries and water splitting. Herein, a three‐dimensional (3D) porous nickel foam electrode (NiFe(OH) x NSs/Ni f ) modified with Ni−Fe hydroxide nanosheets (NSs) is prepared by using a fast and facile electrodeposition method. The electrode is subsequently applied in the electrolysis of Na 2 CO 3 /NaHCO 3 to produce hydrogen, oxygen, NaOH, and NaHCO 3 /CO 2 . By carefully controlling the electrodeposition time, ultrathin NiFe(OH) x NSs with a thickness of approximately 2–6 nm are interlaced with one another and grown vertically on nickel foam to form a hierarchical composite electrode. The prepared NiFe(OH) x NSs/Ni f electrode exhibits superb OER performance with an overpotential of 260 mV at 10 mA cm −2 and a low Tafel slope of 29 mV dec −1 in 1 mol L −1 NaOH solution. In 0.5 mol L −1 Na 2 CO 3 /NaHCO 3 solution, the NiFe(OH) x NSs/Ni f electrode exhibits a low OER potential of 290 mV, which is lower than the commercial RuO 2 /Ti electrode at a current density of 100 mA cm −2 , and shows good long‐term stability. During electrolysis of Na 2 CO 3 /NaHCO 3 , the cell voltage with the NiFe(OH) x NSs/Ni f anode is 2.52 V, which is 280 mV lower than that with a commercial RuO 2 /Ti anode.