Practices in large-scale hydrolysis hydrogen production requires low-cost non-precious metal catalysts with high-efficiency. In this work, amorphous/polycrystalline [email protected] hollow nanochains are in-situ fabricated by applying gas-phase phosphating on CoB nano-chains. As expected, the formation of amorphous/polycrystalline with partially hollow structures and P-doping increased the number of exposed active sites, and altered the electronic structure of Co. As a result, the electron transfer and Hydrogen Evolution Reaction (HER) performance are enhanced. Based on the Kirkendall effect, the fabricated [email protected] catalyst generates a current density of 10 mA cm−2 at overpotential of 135 mV, which is much lower than the reported value of 250 mV for amorphous CoB nanoparticles.