Facile synthesis of low-cost Fe₃C-nitrogen and phosphorus co-doped porous carbon nanofibers: The efficient hydrogen evolution reaction catalysts

Developing high-efficiency Fe-based catalysts towards HER (hydrogen evolution reaction) is critical to cheaply produce clean hydrogen energy by water electrolysis. In this paper, we design a novel Fe₃C nanoparticles embedded and nitrogen and phosphorus co-doped porous carbon nanofibers (denoted as Fe₃C-NP-PCFs). As the activation efficacy of phosphoric acid in the pyrolysis processes, the resultant 3D Fe₃C-NP-PCFs networks acquire a larger surface area, more meso/macroporous structures, more carbon edges/defects and more HER active sites (such as Fe₃C@C units, N–C bonds and P–C bonds) than the Fe₃C–N-PCFs control sample. The electrochemical test results indicate that the optimal Fe₃C-NP-PCFs display excellent E_onset and E₁₀ values of −113.61 and −197.85 mV vs. RHE toward HER in 0.5 M H₂SO₄, which are just 80 and 132 mV more negative than those of commercially available 20 wt% Pt/C (E_onset = −33.86 mV vs. RHE and E₁₀ = −65.75 mV vs. RHE), respectively. Meanwhile, the Fe₃C-NP-PCFs also exhibit a superior long-term stability toward HER catalysis. At last, this work opens a new avenue for further boosting the HER catalytic ability of Fe-based electrocatalysts, which may expedite the commercialization processes of Fe-based HER electrocatalysts.