An ultra-thin and super-long Na₂V₆O₁₆·xH₂O nanoribbon of ∼5 nm thickness and ∼500 μm length was synthesized by a hydrothermal method, using a freshly prepared V(3+) species precursor solution by directly dissolving a vanadium metal thread in a NaNO₃ solution using a solid-liquid phase arc discharge (SLPAD) technique. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques were used to characterize the structure, morphology, and chemical composition. The super-long and ultra-thin geometry of the Na₂V₆O₁₆·xH₂O nanoribbons is proven to greatly promote the photocatalytic activity toward reduction of CO₂ into renewable hydrocarbon fuel (CH₄) in the presence of water vapor under visible-light irradiation.