Effect of Different Trace Iron-Doped ZIF-67 Materials for the Hydrogen Evolution Reaction.

The development of a catalyst that is efficient, clean, simple, inexpensive, and conducive to a wide range of industrial applications is the key to achieving water electrolysis for hydrogen production. In this paper, iron-doped ZIF-67 materials were synthesized using a one-step hydrothermal method, with the different molar ratios of n (Fe3+): n (Co2+) = 0.05%, 1%, 2%, 5%, 10%. We found that trace amounts of iron greatly changed the particle size of ZIF-67. After high-temperature pyrolysis (400 °C, 600 °C, and 800 °C), the electrochemical results showed that the content of doped iron and different pyrolysis temperatures lead to different hydrogen evolution reaction (HER) effects. The 1% Fe/Co-600 sample with the overpotential (202 mV) at 10 mA·cm-2 and the Tafel slope (125.1 mV·dec-1) was significantly lower than other iron-doped materials and exhibited a better HER performance, though still higher than the commercial Pt/C (5 wt %) catalyst with the overpotential of 179 mV at 10 mA·cm-2 and the Tafel slope of 67.8 mV·dec-1. Significantly, the 1% Fe/Co-600 sample has strong stability. After pyrolysis, the 1% Fe/Co-600 sample still had a large specific surface area of 290.1763 m2·g-1 and a porous structure consisting of micropores and mesopores, which improved the catalytic effect. It may provide a new way to modify the catalyst geometry and design and prepare low-cost and high-activity Co-based catalysts.