Nanostructured transition metal compounds coated 3D porous core-shell carbon fiber as monolith water splitting electrocatalysts: A general strategy

[Display omitted] •Core-double-shell architecture was designed as efficient HER and OER electrocatalysts.•Cobalt phosphide and NiFe-LDH were used as representative HER and OER catalysts.•The architecture consist of core–shell porous carbon fiber (CFC@EC) and TMCs.•Lattice distortions were created in the TMCs by CFC@EC, facilitating the exposure of active sites.•Enhanced performance is due to the strong electronic interaction between the hybrids. Different transition metal compounds (TMCs) nanostructures grown on conductive substrates have been considered as promising self-supportive non-precious electrocatalysts for electrochemical water splitting, but extremely challenging to develop facile and generalized approaches for rational design and enhancing their catalytic properties. Herein, we develop a general strategy to boost the hydrogen and oxygen evolution reactions (HER and OER) performance of TMCs by designing monolith electrocatalyst architectures. The monoliths comprises of TMCs integrated on carbon fiber cloth core–shell (CFC@EC) structure. The CFC@EC allows the creation of numerous lattice distortions and strong electronic interactions between CFC@EC and metal cations of the TMCs. Such lattice distortions exposes more active sites in CFC@EC/TMCs compared to the pristine CFC coated TMCs (CFC/TMC). Cobalt phosphide (CoP) nanowires and NiFe-LDH coated on CFC@EC exhibits the optimized HER and OER activities. Overall water splitting device assembled based on the optimized HER and OER electrodes also achieve low overall potential of 1.53 V at 10 mA cm−2. More importantly, we further experimentally verify that the integration of Ni3N and Ni3S2, CoS2, NiCo-LDH, NiMn-LDH with CFC@EC also reveal similar improved performance, providing a general and valuable strategy into the design of other self-supporting electrocatalysts for water splitting and beyond.