Anion-doping Optimizes Metal Bonds for Promoting Hydrogen Evolution Performance of NiMoN Catalysts

It is important to design a stable and efficient hydrogen evolution catalyst in a wide pH range for the development of hydrogen production from water splitting. This work synthesizes a series of anion (R = F, Cl, and CO3)-doped NiMoN catalysts, and their morphological structures can be efficiently regulated by selecting different dopant anions. In particular, the Cl-NiMoN exhibits nano-flower and nano-sheet morphology due to the formation of electron-rich Ni and high valence Mo on the surface of Cl-NiMoN. Compared to other three samples (F-NiMoN, CO3-NiMoN and F, CO3-NiMoN), the synergistic effect of Cl and NiMoN optimizes the ratio of metal-bonding (Ni-N/Mo-N = 0.65), which therefore presents excellent hydrogen evolution (HER) performance. Cl-NiMoN requires only 107 mV overpotential in KOH and only 114 mV overpotential in H2SO4 to drive a current density of 100 mA cm-2 accompanying with excellent catalytic stability. Actually, their HER activity follows the order of Cl-NiMoN > F-NiMoN > F, CO3-NiMoN > CO3-NiMoN. This work provides a new route of using the anion-doping strategy to develop the electrocatalyst with excellent performance.