Electrodeposition of NiFe-layered double hydroxide layer on sulfur-modified nickel molybdate nanorods for highly efficient seawater splitting

Developing high-efficiency and earth-abundant electrocatalysts for electrochemical seawater-splitting is of great significance but remains a grand challenge due to the presence of high-concentration chloride. This work presents the synthesis of a three-dimensional core-shell nanostructure with an amorphous and crystalline NiFe-layered double hydroxide (NiFe-LDH) layer on sulfur-modified nickel molybdate nanorods supported by porous Ni foam (S-NiMoO4@NiFe-LDH/NF) through hydrothermal and electrodeposition. Benefiting from high intrinsic activity, plentiful active sites, and accelerated electron transfer, S-NiMoO4@NiFe-LDH/NIF displays an outstanding bifunctional catalytic activity toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both simulated alkaline seawater and natural seawater electrolytes. To reach a current density of 100 mA cm(-2), this catalyst only requires overpotentials of 273 and 315 mV for OER and 170 and 220 mV for HER in 1 M KOH + 0.5 M NaCl freshwater and 1 M KOH + seawater electrolytes, respectively. Using S-NiMoO4@NiFe-LDH as both anode and cathode, the electrolyzer shows superb overall seawater-splitting activity, and respectively needs low voltages of 1.68 and 1.73 V to achieve a current density of 100 mA cm(-2) in simulated alkaline seawater and alkaline natural seawater electrolytes with good Cl resistance and satisfactory durability. The electrolyzer outperforms the benchmark IrO2 parallel to Pt/C pair and many other reported bifunctional catalysts and exhibits great potential for realistic seawater electrolysis. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study develops an efficient and abundant electrocatalyst for electrochemical seawater-splitting, which exhibits outstanding bifunctional catalytic activity in alkaline seawater and natural seawater electrolytes, making it a promising candidate for realistic seawater electrolysis.