Carbon nanofibers as nanoreactors in the construction of PtCo alloy carbon core-shell structures for highly efficient and stable water splitting

•PtCo alloy carbon core-shell nanostructures with nitrogen doping were synthesized.•Carbon nanofibers served as nanoreactors.•The PtCo alloy carbon exhibits high HER and OER activity and high stability.•The OER activities originate from the conductivity of NCNF and the PtCo alloy.

Carbon nanofibers served as nanoreactors for the design and construction of PtCo alloy carbon core-shell nanostructures with nitrogen doping (PtCo/NCNF) through a combination of electrospinning and nitrogen doping treatments. The PtCo/NCNF hybrid consists of PtCo alloy nanoparticles surrounded by a few of N-doped carbon layers, demonstrating a typical core-shell structures. The PtCo/NCNF hybrid can both served as electrode materials for electrocatalytic water splitting including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). For the HER performance, the PtCo/NCNF exhibits very small onset potential of 20 mV, an overpotential of 50 mV at a j (vs RHE) = 10 mA cm− 2 and Tafel slope of 30 mV dec− 1. The PtCo/NCNF hybrid also exhibits high OER activity with an onset potential of 310 mV, an overpotential of 400 mV at a j of 10 mA cm− 2 and a small Tafel slope of 76 mV dec− 1. The high catalytic activities of PtCo alloy for HER and OER originate from the 3D hierarchical structures, well-dispersed PtCo alloy, high conductivity of NCNF, protection from the carbon-encapsulated structure, and the introduction of nitrogen.

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