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.

Lacunary polyoxometalates (LPOMs), a class of anionic metal oxide clusters, are promising materials as catalysts, photocatalysts, and electrocatalysts. Designing and functionalizing this type of compound are key factors for the discovery and development of novel materials. Herein, a new lacunary polyoxometalate-based compound was designed as a heterogeneous catalyst, prepared through functionalization of a lacunary Keggin-type polyoxometalate, i.e., [PMo11O39]7–, with 3-aminopropyltrimethoxysilane (APTS) and 2-pyridine carboxaldehyde. Subsequent reactions of this compound with Cu2+ ions led to the desired catalyst, LPMo-Cu. The catalytic activity of the obtained LPMo-Cu was examined in nitroarene reduction using sodium borohydride as a reducing agent in aqueous solution. It was specified that the synthesized LPMo-Cu exhibits high catalytic efficiency in the reduction of a wide variety of nitroarenes in a short time (5 min). Furthermore, the stability and recoverability of the prepared material were proved as a result of four consecutive reduction cycles without a significant decrease in its efficiency.

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