Improved the Electrocatalytic Hydrogen Evolution Performances of Co-MOF Derivatives Through Introducing Zinc Ions by Two Ways

Due
to the high price and rareness of precious metal electrocatalysts,
the preparation of cheap, high-efficiency nonprecious metal electrocatalysts
is urgently needed. In this paper, a Co-metal-organic framework (MOF)
has been synthesized by the hydrothermal method. In view of the poor
electrocatalytic performance of pristine Co-MOF, we used it as a template
and obtained the Co-MOF-800 electrocatalyst by high-temperature calcination
at 800 °C under a nitrogen atmosphere. To further improve the
electrocatalytic hydrogen evolution performance, we used two methods
to synthesize cobalt/zinc bimetallic-based electrocatalysts. The first
method is adding zinc ions to Co-MOF and stirring to obtain Co-MOF@Zn;
the second method is adding zinc ions during the in situ synthesis
to obtain Co/Zn-MOF. Finally, Co-MOF@Zn-800 and Co/Zn-MOF-800 were
obtained by pyrolysis at 800 °C under a nitrogen atmosphere.
The electrocatalytic hydrogen evolution results show that Co-MOF@Zn-800
and Co/Zn-MOF-800 obtained by doping and introducing zinc ions have
larger specific surface areas of 369.837 and 347.898 m2 g–1, respectively, and better electrocatalytic
hydrogen evolution performances in 0.5 M sulfuric acid. The overpotentials
are 218 and 236 mV at a 10 mA cm–2 current density,
and the Tafel slopes are 146.6 and 187.0 mV dec–1. After 40 h of stability testing, the Co-MOF@Zn-800 material still
holds a nearly constant current density.