Laser Assisted Anchoring of Cadmium Sulfide Nanospheres into Tungsten Oxide Nanosheets for Enhanced Photocatalytic and Electrochemical Energy Storage Applications

Abstract 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 minutes. Also, when the same nanocomposite is used as an electrode material in the supercapacitor, the areal capacitance (Ca) 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.