Laser-induced anchoring of WO₃ nanoparticles on reduced graphene oxide sheets for photocatalytic water decontamination and energy storage

In this work, the synthesis of tungsten oxide/reduced graphene oxide (WO₃-rGO) nanocomposite, using a simple method of pulsed laser ablation in liquids (PLAL) is reported. The pulsed laser beam of 355 nm wavelength carries out two simultaneous processes: the reduction of graphene oxide and at the same time the anchoring of nanostructured WO₃ on reduced graphene oxide. In the photo-catalytic application, WO₃-rGO shows much better visible light absorption and less photo-generated charge recombination than pure WO₃, as indicated by optical absorption and photoluminescence spectra. These improved features in WO₃-rGO significantly enhanced the photo-catalytic decontamination of methylene blue (MB) dye in the water, compared to the use of pure WO₃ as a photocatalyst. A Poly 2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) based electrolyte together with the high electrical conductance and porosity of rGO which were produced after anchoring WO₃ on the graphene oxide, were harnessed for the energy storage application using this material for a supercapacitor. The specific capacitance for WO₃-rGO based device is achieved to be 577 F g⁻¹ measured by the galvanostatic charge-discharge (GCD) method. Also, at a power density of 1000 W kg⁻¹, the as-synthesized WO₃-rGO demonstrated a large energy density value of 76.3 Wh Kg⁻¹ that is much larger than obtained, using WO₃ alone. Besides these photocatalytic and energy storage performance evaluation of WO₃-rGO, the optical, morphological and elemental characteristics of synthesized WO₃-rGO were also investigated to study the improved performance of the nanocomposite in these two applications.