S-doped NiFe layered double hydroxide with a large surface area for efficient oxygen evolution reaction

Nickel-iron hydroxides have been considered as a popular cost-effective catalyst toward the oxygen evolution reaction (OER). However, the extensive utilization of nickel-iron hydroxide electrocatalysts still suffer from the limited electrical conductivity. Anionic doping has demonstrated its beneficial impact in stabilizing the lamellar structures, and enhancing the conductivity of NiFe layered double hydroxide (NiFe-LDH) for OER. In this work, sulfur-doped NiFe-LDH nanoparticles with high surface area and porous structure were effectively synthesized through low-temperature co-precipitation and subsequent solid-phase sulfurization. Moreover, sulfur doping activated the formation of oxygen vacancies, thereby enhancing the conductivity. S-doped NiFe-LDH catalysts exhibited high electrocatalytic performance toward oxygen evolution reaction, displaying the overpotentials of 220 mV and 284 mV at 10 mA cm- 2 and 100 mA cm- 2, respectively, lower than those of NiFe-LDH precursors and commercial RuO2. Moreover, the catalysts exhibited superior performance at large current density by delivering low overpotentials and good durability when used Ni foam as substrate. This work clarifies the advantage of low-temperature co-precipitation strategy and solid-phase sulfurization in constructing the porous electrocatalysts, which may represent a promising strategy for designing highly active hydroxide catalysts.