Coupling of NiFe-based Metal-organic Framework Nanosheet Arrays with Embedded Fe-Ni3S2 Clusters as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Developing highly efficient, easy-to-make and cost-effective bifunctional electrocatalysts for water splitting with lower cell voltages is crucial to producing massive hydrogen fuel. In response, the coupled hierarchical Ni/Fe-based MOF nanosheet arrays with embedded metal sulfide nanoclusters onto nickel foam skeleton (denoted as Fe-Ni3S2@NiFe-MOF/NF) are fabricated, in which the Fe-Ni3S2 clusters could effectively restrain the aggregation of the layer metal-organic frameworks (MOF) nanosheets and adjust the local electronic structures of MOFs nanosheets. Benefiting from the rapid charge transfer and the exposure of abundant active sites, the well-designed Fe-Ni3S2@NiFe-MOF/NF displays excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance. More importantly, when equipped in the alkaline water electrolyzer, the Fe-Ni3S2@NiFe-MOF/NF enables the system with a mere 1.6 V for achieving the current density of 10 mA cm(-2). This work offers a paradigm for designing efficient bifunctional HER/OER electrocatalysts based on the hybrid materials of nanostructured metal sulfide and MOF.