Co-doped NiFe-LDH nanosheets arrays supported on nickel foam as an efficient oxygen evolution electrocatalysis

In the field of water electrolysis for hydrogen production, NiFe-layered double hydroxides (NiFe-LDH) is currently one of the most excellent oxygen evolution electrocatalyst. However, its application in this field is limited due to its low durability, low conductivity and few active sites. In this work, we present a Co-introduced fine-modulated NiFe-LDH performance strategy to construct Co-doped NiFe-LDH nanosheets arrays supported on nickel foam (Co-NiFe-LDH/NF). The optimized Co-NiFe-LDH/NF showed ultralow overpotentials at 211, 237, 261 and 281 mV at 50, 100, 200 and 300 mA cm-2 current densities, separately, with an extremely low Tafel slope (40 mV dec- 1). The Co-NiFe-LDH/NF was highly stable during the constant current test, and the potential increased by only 10 and 13 mV after 100 h stability test at 200 and 300 mA cm-2. Notably, it also works stably at the 500 and 1000 mA cm-2 very high current densities, representing high potential of commercial application. The theoretical calculation showed that: (1) Introducing Co into NiFe-LDH can reduce the energy barrier of OH* conversion to O* and increase the activity of OER; (2) Considering the formation energy, Co is more likely to replace Fe site in NiFe-LDH than Ni site; (3) The energy barrier, differential charge and partial density of states analysis show that the best OER performance is obtained when the Fe-to-Co ratio of 2:1, and the theoretical calculation is consistent with the experimental verification. This work provides a simple and effective method for the design and construction of doping elements into NiFe-LDH electrocatalysts for efficient water oxidation, and promoted NiFe-LDH material application in commercial alkaline water electrolysis cell.

Automated summary

In this study, a Co-introduced fine-modulated NiFe-LDH performance strategy was proposed and successfully used to construct Co-doped NiFe-LDH nanosheets arrays. The optimized nanosheets showed low overpotentials and an extremely low Tafel slope. The stability test proved the good stability of the nanosheets even at high current densities. The theoretical calculation was consistent with the experimental verification, providing a simple and effective method for designing and constructing efficient water oxidation catalysts.