Super-Hydrophilic Co- and Mo-Based Mix-Metallomicellar Film as an Electrocatalyst toward Hydrogen Evolution Reaction

Abstract

A rational design and facile synthesis that is based upon inexpensive and earth-abundant elements is an effective strategy for electrochemical hydrogen evolution reaction (HER). Herein, we have utilized single-chain metallosurfactants (CoDDA(I) and MoDDA(I)) to develop a mix-metallomicellar film (Co-MoDDA(I)) that is used as an electrocatalyst toward HER. To our knowledge, there have been no reports on mix-metallomicellar films toward HER. Experimental results reveal that the HER activity of Co-MoDDA(I) was comparable with commercial Pt/C (20 wt %), a low Tafel slope (29.2 mV dec–1), and long-term stability. The dramatically improved HER performance of Co-MoDDA(I) was favored by the combination of the following factors: formation of reverse micelles, super-hydrophilic characteristic, and presence of Co(II) and Mo(III) ions in the micellar core. Organic media pushed the Co of CoDDA(I) toward the core of the reverse micelles, which further attracts the Mo ions of MoDDA(I) to form a mixed micellar film. The cooperative effect of Co and Mo in the reverse micellar core generates the catalytic center for efficient hydrogen production. In situ reduction of Co and the synergic effect between 3d (Co) and non 3d (Mo) metal ions in the core of micelles accelerate the HER reaction rate effectively. Several chemical changes were also observed in the material, i.e., removal of chloride ions from the surface and reduction of Co inside the core of reverse micelles as authenticated by X-ray photoelectron spectroscopy (XPS). However, surface characteristics were verified by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Metallosurfactants are available to provide controllable structure, orientation, and structural stability and assist to detach the bubbles from the surface.