Electrocatalytic Hydrogen Evolution Reaction of Rhenium Metal and Rhenium-Based Intermetallic in Acid and Alkaline Media

Rhenium (Re) metal has been well known for the high corrosion resistance in strong acid and alkaline electrolyte, which makes it a potential electrocatalyst toward hydrogen evolution reaction (HER). However, the low HER activity (>100 mV @ 10 mA/cm(2)) is a fatal flaw and the reason Re metal does not receive much attention comparing to other noble metal such as Platinum (Pt), Iridium (Ir) and Ruthenium (Ru). To improve the HER activity of Re metal, in this work, we have incorporated a small amount of Zr atoms into Re lattice to form Re based intermetallic Zr5Re24. The large Zr atoms can expand the subunits of the structure and increase the Re-Re bond lengths while the low electronegativity of Zr atoms will donate electrons to Re atoms and fill more antibonding state of Re-Re bond. Both crystal-structural and electronic-structural factors will reduce the bond strength of Re-Re bond and thus weaken the corresponding hydrogen adsorption energy (Delta GH(ad)). This can adjust the Delta GH(ad) of Zr5Re24 to an optimal position and enhance the HER activity from Re metal (eta(10)similar to 125 mV) to Zr5Re24 (eta(10)similar to 90 mV). Moreover, it was realized that OH molecule on the surface of Zr5Re24 and Re metal will not occupy the most active site (i. e. poison effect) nor significantly influence the Delta GH(ad) to the optimized position (i. e. 0 eV), which well elucidate the similar HER activity in acid or alkaline electrolyte.