Hierarchical ultrathin NiFe-borate layered double hydroxide nanosheets encapsulated into biomass-derived nitrogen-doped carbon for efficient electrocatalytic oxygen evolution

Abstract

Exploring highly efficient, cost-effective, and stable electrocatalysts toward oxygen evaluation reaction (OER) is of great significance for hydrogen generation. Herein, in situ growth of NiFe-borate layered double hydroxide (NiFe-BLDH) nanosheets on waste biomass-derived nitrogen-doped carbon (NC) with hierarchical architecture under microwave hydrothermal conditions is reported. The as-synthesized NiFe-borate layered double hydroxide/nitrogen-doped carbon (NiFe-BLDH/NC) exhibits outstanding OER activity, showing an extremely low overpotential of 243 mV at the current density of 10 mA cm−2 and a relatively small Tafel slope of 42.7 mV dec−1, which are superior to the commercial RuO2 and many previously reported NiFe-LDH-based OER electrocatalysts. Additionally, the catalyst also shows remarkable stability with unobvious decrease of current density over a period of 24 h. These excellent catalytic performances could be attributable to the synergistic effects between the conductive NC scaffold and NiFe-BLDH with excellent hydrophilicity caused by the intercalated borate anions, which provide many advantages, such as large surface area, abundant active sites, fast charge and mass transport pathways. This work provides new insights into the design and facile preparation green and efficient electrocatalysts