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.