Lacunary Polyoxometalate iImmobilized on Graphene Oxide: An Effective Electrocatalyst for Hydrogen Generation in Aqueous Solution

A nanocomposite based on the interaction of a lacunary polyoxometalate and modified graphene oxide was designed for utilization as an electrocatalyst for hydrogen evolution reaction.

Abstract

A new stable nanocomposite comprising thiol-functionalized lacunary Keggin-type phosphomolybdate (PMo₁₁) and graphene oxide (GO) was prepared via the thiol-ene click reaction. Various characterization techniques, like FT-IR spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD) analysis showed the strong covalent interaction of GO and PMo₁₁ species and successful formation of PMo₁₁−S−GO nanocomposite. Nitrogen adsorption-desorption analysis revealed the decrease in GO surface area after introducing PMo₁₁ species. The prepared nanocomposite was employed in the electrocatalytic hydrogen evolution reaction (HER) in 0.5 M H₂SO₄ solution. A low overpotential of 335 mV and small Tafel slope of 71 mV.dec⁻¹ were obtained in electrocatalytic HER experiments. The nanocomposite exhibited high stability and negligible loss of electrocatalytic activity for at least 850 cycles which is a result of the stable covalent attachment of lacunary Keggin type phosphomolybdate to the surface of GO nanosheets.

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