Coordination confinement pyrolysis to Flower-like nanocomposites composed of ultrathin nanosheets with embedded ultrasmall CoP nanoparticles for overall water splitting

Highlights: • Coordination confinement pyrolysis strategy was developed to produce a flower-like electrocatalyst composed of ultrathin nanosheets. • The ultrathin nanosheets with embedded ultrasmall CoP nanoparticles offer numerous active sites and accelerates the mass transfer. • The electrocatalyst realizes satisfying electrocatalytic efficiency with overpotentials of 143 mV and 298 mV for HER and OER at 10 mA·cm^-1. • Electrocatalytic mechanisms were studied by XPS, TEM, XPS, UPS, Raman, et al. Electrocatalytic water splitting is being widely studied to produce low-cost and clean fuels for energy saving and conversion. However, the development of efficient and stable electrocatalysts remains a huge challenge. In this study, a novel coordination confinement pyrolysis method was demonstrated to construct an efficient bifunctional electrocatalyst with inherited hierarchical flower-like morphology, in which the ultra-small CoP nanoparticles with ca. 4 nm in size were successfully embedded into the nanosheet assembly unit. The resulted catalyst product with a unique three-dimensional structure not only realizes the satisfying catalytic efficiencies with overpotentials of 143 and 298 mV for HER and OER at the current density of 10 mA·cm⁻², but also delivers suitable stability after long-term electrolytic process. Therefore, this catalyst design concept integrating ultra-small nanoparticles, ultra-thin nanosheets, and three-dimensional assembly could provide a novel idea to evolve the other heterogeneous catalysts.