Nitrogen and gold nanoparticles co-doped carbon nanofiber hierarchical structures for efficient hydrogen evolution reactions

•AuNPs on N doped carbon nanorods encapsulating carbon nanofibers was fabricated.•The hierarchical structure was demonstrated as an electrocatalyst for HER.•The electrocatalysts exhibit high HER activity and stability.•The activity is attributed to synergetic effect between N doped CFs and AuNPs.

A novel hierarchical structure was fabricated by integrating gold nanoparticles (AuNPs) on nitrogen-doped carbon nanorods encapsulating carbon nanofibers (AuNPs@NCNRs/CNFs), and the composite was demonstrated as an electrocatalyst for the hydrogen evolution reaction (HER). First, polyaniline nanorods (PNRs) were grown on the surfaces of the CNFs, and the PNR/CNF hybrids were then decorated with small, well-dispersed and size-controlled AuNPs. The morphology, structure and chemical states of the AuNPs@NCNRs/CNFs hybrids were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The AuNPs@NCNRs/CNFs can be used directly as an electrode and exhibit good HER activity with a relatively low onset potential of 126 mV, a Tafel slope of 93 mV dec−1 and remarkable durability in 0.5 M H2SO4. The enhancement of the HER activity could be attributed to the synergetic effect between the nitrogen-doped carbon fibers and the AuNPs.