In this article, electro catalyst was synthesized easily for Hydrogen Evolution Reaction (HER). The electro catalyst contain Co 3 O 4 nanoparticles on three dimensional carbon nanotubes as nanoparticles bed. Having high surface area and low charge transfer resistance are the three dimensional carbon nanotubes significant specifications which are so important for suitable bed in electro catalyst. Electrochemical properties of Co 3 O 4 /3D CNTs were investigated in 0.50 M H 2 SO 4 solution and 1.0 M KOH solution separately and compare the result with Pt electro catalyst (Pt/C 30%) as an ideal HER electro catalyst. In acidic solution, Co 3 O 4 /3D CNTs and Pt/C 30% have the similar demeanor like high current density (1200mA/cm 2 ), low onset potential (0/24 V) and high stability (more than 10000 cycles); also synthesized electro catalyst has desirable behavior in alkaline solution in contrast. For figuring out the mechanism of the HER reactions in both solutions, Tafel slop was used; Volmer- Heyrovsky mechanism in H 2 SO 4 0/50 M solution and Volmer-Tafel mechanism in KOH 1/0 M solution were conformed.
