Fabrication of cobalt-nickel double hydroxide nanosheet electrocatalysts embedded in carbon nanocomposites for efficient usage of oxygen evolution reaction

The main innovation of this work is the design of ultrathin CoNi-LDH nanosheets encapsulated in a conductive carbon layer via polypyrrole coating and subsequent carbonization. The key scientific problem addressed is the intrinsically poor electron transfer and limited active site exposure of pristine layered double hydroxides for efficient oxygen evolution reaction (OER). CoNi-LDH@C was synthesized by a facile hydrothermal method followed by polypyrrole coating and carbonization. The composite consists of radially grown CoNi-LDH nanosheets with a loose layered structure, large surface area, and enhanced conductivity. For OER in 1.0 M KOH, it achieves a low overpotential of 231 mV at 20 mA cm −2 , a small Tafel slope of 35 mV dec −1 , and remarkable long-term stability with 94.6% retention after 15 h. This work provides an effective strategy to simultaneously improve conductivity and active site accessibility in LDH-based materials for high-performance OER electrocatalysts.