Ultrasmall Co-NiP embedded into lantern shaped composite achieved by coordination confinement phosphorization for overall water splitting

Currently, the challenges remain for developing promising water splitting electrocatalyst, and the non-noble metal-based catalytic materials are ideal alternatives. This study reported a hierarchical lantern Ni-doped Co-MOF synthesized by simple stirring at room temperature, which further generated an efficient bifunctional Ni-doped CoP@carbon-nitrogen (Co-NiP@NC) water splitting electrocatalyst using a coordination confinement phosphating approach, and the Co-NiP nanoparticles (ca. 5 nm) were successfully embedded into the NC nanosheets. This catalyst shows excellent catalytic efficiency with 140 mV overpotential for hydrogen evolution reaction (HER) at the current density of 10 mA·cm−2 in 1.0 M KOH. Meanwhile, it can be used as an ideal catalyst for catalyzing oxygen evolution reaction (OER) with the overpotential of 280 mV under the same conditions. Thus, only a voltage of 1.67 V was required to realize the overall water splitting at the current of 10 mA·cm−2 when the Co-NiP@NC catalyst could act as both electrodes. Additionally, the catalyst displays the excellent HER, OER, and over water splitting (OWS) stabilities after 24 h, and the potentials decrease are feeble 2.7%, 2.9%, and 1.7%. Overall, the coordination confinement pyrolysis generated catalyst integrates the advantages of super small nanoparticles and rich hierarchical structure, providing new storage to design efficient electrocatalysts.