Evaluating the Hydrogen Evolution Reaction Activity of Colloidally Prepared PtSe 2 and PtTe 2 Catalysts in an Alkaline Medium.

The hydrogen evolution reaction (HER) in alkaline electrolytes using transition metal dichalcogenides is a research area that is not tapped into. Alkaline HER ( 2 H 2 O + 2 e - → H 2 + O H - ${{2H}_{2}O+2{e\ }^{-}\to {H}_{2}+{OH}^{-}{\rm \ }}$ ) is harder to achieve relative to acidic HER ( H + + 2 e - → H 2 ${{H}^{+}+2{e\ }^{-}\to \ {H}_{2}}$ ), this is attributed to the additional water dissociation step that occurs in basic HER to generate H + ions. In fact, for most catalysts, their HER activity decreases tremendously when the electrolyte is changed from acidic to basic conditions. Platinum dichalcogenides, PtX 2 (X=S, Se, Te), are an interesting member of transition metal dichalcogenides (TMDs) as these show an immense hybridization of the Pt d orbitals and chalcogen p orbitals because of closely correlated orbital energies. The trend in electronic properties of these materials changes drastically as the chalcogen is changed, with PtS 2 reported to exhibit semi-conductor properties, PtSe 2 is semi-metallic or semi-conductive, depending on the number of layers, while PtTe 2 is metallic. The effect of varying the chalcogen atom on the HER activity of Pt dichalcogenides will be studied. Pt dichalcogenides have previously been prepared by direct high-temperature chalcogen deposition of Pt substrate and evaluated as electrocatalysts for HER in H 2 SO 4 . The previously employed synthesis procedures for PtX 2 limit these compounds' mass production and post-synthesis treatment. In this study, we demonstrated, for the first time the preparation of PtSe 2 and PtTe 2 by colloidal synthesis. Colloidal synthesis offers the possibility of large-scale synthesis of materials and affords the employment of the colloids at various concentrations in ink formulation. The electrochemical HER results acquired in 1 M KOH indicate that PtTe 2 has a superior HER catalytic activity to PtSe 2 . A potential of 108 mV for PtTe 2 and 161 mV for PtSe 2 is required to produce a current density of -10 mA cm -2 from these catalysts. PtTe 2 has a low Tafel slope of 79 mVdec -1 , indicating faster HER kinetics on PtTe 2 . Nonetheless, the stability of these catalysts in an alkaline medium needs to be improved to render them excellent HER electrocatalysts.