Highly efficient and stable electrocatalysts from inexpensive and earth-abundant elements are emerging materials in the overall water splitting process. Herein, cobalt iron hydroxide nanosheets are directly deposited on nickel foam by a simple and rapid electrodeposition method. The cobalt iron hydroxide (CoFe/NF) nanosheets not only allow good exposure of the highly active surface area but also facilitate the mass and charge transport capability. As an anode, the CoFe/NF electrocatalyst displays excellent oxygen evolution reaction catalytic activity with an overpotential of 220 mV at a current density of 10 mA cm . As a cathode, it exhibits good performance in the hydrogen evolution reaction with an overpotential of 110 mV, reaching a current density of 10 mA cm . When CoFe/NF electrodes are used as the anode and the cathode for water splitting, a low cell voltage of 1.64 V at 10 mA cm and excellent stability for 50 h are observed. The present work demonstrates a possible pathway to develop a highly active and durable substitute for noble metal electrocatalysts for overall water splitting.

The replacement of noble-metal-based electrocatalysts with earth-abundant, low-cost bifunctional electrocatalysts for efficient hydrogen generation is required. Herein, an amorphous and porous 2D NiFeCo hydroxide nanosheets grown on nickel foam (NF) (NiFeCo LDH/NF) by a cost-effective electrodeposition method was explored for efficient electrolytic water splitting and urea electrolysis. Experimental results show that porous confinement in 2D orientation, amorphous nature, and synergistic effect leads to the excellent catalytical performance of the as-prepared 2D NiFeCo LDH/NF electrode for overall water splitting and urea electrolysis. The NiFeCo LDH/NF electrode presents promising behavior for water electrolysis with a small overpotential of 210 mV and 108 mV, respectively, is required for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) to gain 10 mA cm −2 . More notably, the bifunctional NiFeCo LDH/NF catalyst, for water electrolysis, needs a lower potential of 1.57 V to gain 10 mA cm −2 in 1 KOH. Furthermore, the electrochemical urea oxidation results show that NiFeCo LDH/NF requires just 0.280 V (vs SCE) to drive 10 mA cm −2 in 1 M KOH with a 0.33 M urea, whereas urea-mediated electrolysis cells require a very low potential of 1.49 V at 10 mA cm −2 . The present results provide remarkable and notable insights into the preparation of non-noble and highly efficient 2D transition metal hydroxide electrocatalysts with performances that allow them to compete for widespread use in various applications.

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