| Summary: | Wastewater from textile dyeing industries has been identified as one of the main sources of water pollutant. As the industries expands, the demand on effective technologies for wastewater treatment is increasing. Photocatalysis dye wastewater treatment has been identified as an alternative to conventional dye wastewater treatment. One of the advantages of using photocatalyst is the generation of CO2 and H2O as its final product and the photocatalyst itself can be reused. However, their stumbling block is low photocatalysis efficiency under visible light irradiation and required constant photons supplies. Therefore, the present study was conducted to develop WO3-CdS-Ag photocatalyst with energy storage property that can work efficiently under visible light irradiation and in absence of light irradiation. WO3 is being used as a based to CdS particles to evade its tendency of photo corrosion and allows CdS to undergoes photocatalytic activity. Besides that, WO3 facilitates electron transfer to increase recombination of electrons and holes while Ag act as an electron storage. The photocatalyst was synthesized using two step precipitation method. In this study, composition of CdS was kept constant whereas WO3 were varied for 3 g, 5 g, and 10 g during the first step to optimize the performance of visible light photocatalyst. For the second step of the precipitation method, 1 g of optimum WO3-CdS was used to synthesize energy storage visible light photocatalyst. The visible light WO3-CdS photocatalysts from the first precipitation step were characterized by FE-SEM, EDX, FTIR, XRD, UV-Vis-NIR spectrophotometer. The performance of the WO3-CdS photocatalysts were evaluated by measuring degradation of reactive orange 16 (RO16) under visible light irradiation. It was discovered that for the optimum performance of synthesized WO3-CdS composite, band gap energy was reduced to 2.28 eV and subsequently shifted the light absorption towards more visible region as compared to pure WO3 and CdS that have higher band gap energy of 2.8 eV and 2.4 eV respectively. The WO3-CdS photocatalyst were tested for photo degradation of 10 ppm RO16 dye under visible light irradiation for 300 minutes and shows imposing photocatalysis efficiency of up to 64.45 % degradation and 𝑘 value of 0.0034 min-1 as compared to 1.18 % degradation and k value of 0.0006 min-1 for pure CdS and WO3. On the other hand, synthesized of energy storage visible light WO3-CdS-Ag photocatalyst by precipitation method was characterised by FE-SEM, EDX and UV-Vis-NIR spectrophotometer. This energy storage visible light photcatalyst managed to reduce the band gap energy further down to 2.019 eV. Besides that, the percentage of concentration degradation for RO16 reached up to 2.9 % under continuous irradiation in 75 minutes, while in the absence of light, the percentage of concentration degradation approached to 2.4 % for similar time. While the observed degradation percentages are relatively low, due to the obstruction of the photocatalyst's active surface area by Ag, this study confirms the capability of the WO3-CdS-Ag photocatalyst to store energy. It reveals substantial promise for its utilization as a visible light-driven energy storage photocatalyst in the treatment of dye-contaminated wastewater.
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