La-doped NiFe-LDH coupled with hierarchical vertically aligned MXene frameworks for efficient overall water splitting

The development of stable electrocatalysts with high hydrogen and oxygen evolution reactions (HER and OER) activity in alkaline electrolytes is critical to renewable energy conversion technologies, such as electrochemical water splitting. In this work, a novel strategy for engineering water splitting electrocatalysts in alkaline electrolyte was developed by synergistically coupling La-doped NiFe-layered double hydroxides (NiFe-LDH) nanosheets onto three-dimensional (3D) vertically aligned MXene nanosheets on macroporous nickel foam (NF) substrates (NiFeLa-LDH/v-MXene/NF). The electrocatalytic performance of the prepared NiFeLa-LDH/v-MXene/NF is enhanced by the synergy of strong electronic interaction among multiple metal centers and unique vertically aligned porous MXene with increased active surface area, accelerated reaction kinetics and improved water adsorption and dissociation ability. To reach the commercially required current density (500 mA cm−2), the NiFeLa-LDH/v-MXene/NF exhibits greatly reduced overpotentials of 233 and 255 mV for HER and OER, respectively, along with excellent durability. Moreover, an alkaline electrolyzer driven by NiFeLa-LDH/v-MXene/NF delivers a lower cell voltage (1.71 V) compared with that of Pt/C-RuO2 couple to achieve the current density of 500 mA cm−2.