MOF-derived NiCoZnP nanoclusters anchored on hierarchical N-doped carbon nanosheets array as bifunctional electrocatalysts for overall water splitting

The development of novel bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is urgently desired for improving the efficiency of overall water splitting but remains a great challenge. Herein, a metal-organic frameworks (MOFs)-derived hybrid nanostructure consisted of multiple transition metal phosphide (NiCoZnP) nanoclusters and hierarchical ultrathin N-doped carbon (NC) nanosheets is successfully synthesized as binder-free bifunctional electrocatalysts for overall water splitting. The ultrafine and monodispersed NiCoZnP nanoclusters with uniform sizes of 3 nm are homogeneously distributed on the ultrathin NC nanosheets, leading to self-supported NiCoZnP/NC nanosheets array on carbon cloth (CC). The NiCoZnP/NC exhibits large surface area and numerous active sites due to the small sizes of NiCoZnP and hierarchical nanostructures of NC. Furthermore, the NiCoZnP/NC nanosheets are directly grown on CC and avoids the usage of binder, which significantly reduces the electrical contact resistance and exhibits superhydrophilic performance. Therefore, the self-supported NiCoZnP/NC nanosheets array demonstrates high HER activity with low overpotential of 74 mV and OER activity with overpotential of 228 mV to reach current density of 10 mA cm-2 in 1.0 M KOH solution, and exhibits remarkable overall water splitting performances with low potential of 1.54 V to drive 10 mA cm-2 and good long-term stability.