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

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.

Automated summary

A stable nanocomposite consisting of thiol-functionalized lacunary Keggin-type phosphomolybdate (PMo11) and graphene oxide (GO) was successfully prepared by the thiol-ene click reaction. Characterization techniques confirmed the strong covalent interaction and successful formation of the PMo11-S-GO nanocomposite. The nanocomposite exhibited excellent electrocatalytic activity for the hydrogen evolution reaction with low overpotential and small Tafel slope, and also demonstrated high stability for at least 850 cycles due to the stable covalent attachment of PMo11 to GO nanosheets.