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.