Supercritical fluid-mediated exfoliation of NbSe2 and fabrication of RGO-NbSe2 nanostructures for enhanced hydrogen evolution

Abstract

Uniform rod-like NbSe₂ nanostructures were precisely fabricated from bulk NbSe₂ using a one-pot, rapid supercritical fluid process, where a mildly basic solution acted as the exfoliating agent. The formation of NbSe₂ nanorods was confirmed by microscopic analyses. XRD, Raman, and XPS results further validated the successful exfoliation and indicated partial surface oxidation of NbSe₂ into Nb₂O₅ nanostructures during SCF processing. Interestingly, the formation of rod-like NbSe₂ was largely suppressed in the synthesis of RGO-NbSe₂ nanocomposites, as the RGO nanosheets hindered the growth of such morphologies. The synthesized RGO-NbSe₂ nanocomposites exhibited outstanding electrocatalytic activity toward hydrogen evolution, requiring only ∼123 mV overpotential to reach 10 mA cm⁻². This performance notably surpassed that of the pristine NbSe₂ nanorods, which required ∼355 mV for the same current density. This enhancement is attributed to the efficient exfoliation of bulk NbSe₂ into nanosheets, which enhances the exposure of reactive edge sites and promotes the formation of heterostructures with favourable hydrogen adsorption characteristics. The integration with highly conductive RGO further contributes to charge transfer and overall catalytic synergy.