Laser assisted anchoring of cadmium sulfide nanospheres into tungsten oxide nanosheets for enhanced photocatalytic and electrochemical energy storage applications

The nanocomposites of tungsten oxide and cadmium sulfide (WO₃-nCdS) with different mass ratios (n = 0 %, 5 %, 15 %, 30 % and 100 %) of CdS in WO₃ were synthesized by pulsed laser ablation in liquid (PLAL). Anchoring of CdS on WO₃ brought about attractive material characteristics like, enhanced visible light absorption and reduced electron-hole recombination through the z-scheme charge transfer between WO₃ and CdS, which were experimentally confirmed by the absorption spectra and photoluminescence spectra respectively. These new features in the material resulted in the enhancement of photo catalytic degradation of methylene blue (MB) dye under visible light; particularly WO₃-30 %CdS nanocomposite achieved complete dye degradation in 230 min. Also, when the same nanocomposite is used as an electrode material in the supercapacitor, the areal capacitance (C_a) shows an enhancement in general and reached a level as high as 68.1 m F cm⁻² equivalent to 121.2 F g⁻¹ (from charge-discharge analysis), which can be attributed to the increased surface area in the WO₃-nCdS nanocomposite. The fabricated device exhibited sufficiently large energy density of 7.7 μWh cm^-2 corresponding to high power density of 254 μW cm⁻².