Heterogeneous Co–CN nanofibers with controlled active terminal N sites for hydrogen evolution reaction

In this work, a series of Co–CN nanofibers with controlled terminal N, Co–Nx, and metal Co site contents were prepared by electrospinning and high-temperature pyrolysis, which served as model catalysts for identifying the active sites for the hydrogen evolution reaction (HER). The results indicate that the thermal treatment would induce Co–Nx moieties to more terminal N sites with higher loading of the Co precursor, and this terminal N site exhibits excellent HER performance. Meanwhile, the activities were linear in accord with the content of terminal N sites, suggesting that terminal N sites would be the primary sites for hydrogen evolution reaction.