Fabrication and Characterization of MoS2/TiO2 Nanocomposites for Photodegradation of Organic Dyes and Energy Storage Application

Abstract

In this research project, well-organized MoS2/TiO2 (nanosheets/nanoparticles) composites have been prepared via facile sol-gel reflux synthesis without the use of any surfactant and template. The goal was to utilize MoS2 with Titania as a photosensitizer due to its small band gap and to employ this synthesized product for photocatalytic activities. Bulk MoS2 has been exfoliated via liquid phase exfoliation (LPE) process and separated at 1000 and 500rpm centrifugation speeds respectively to obtain sheets of different sizes and densities. These sheets were then added in TiO2 sol in 0.1, 0.5, 1, 2 and 5wt. % ratios respectively. MoS2 nano-sheets acted as a photosensitizer for TiO2 nanoparticles due to their enhanced band gaps. The prepared composites were characterized by SEM, AFM, XRD, Raman analysis, UV-Vis and BET techniques. The SEM results confirmed the adsorption of TiO2 nanoparticles on MoS2 sheets. The AFM results also confirmed the formation of nano-sheet like structure of MoS2. These composite systems were then employed for photodegradation of organic dye (methylene blue) which is effluent produced by industries. Enhanced photodegradation of methylene blue was observed by MoS2 sheets and TiO2 nanoparticles hybrid structures as compared to commercial P25 TiO2 powder and as-prepared anatase TiO2 powder under UV irradiation. Photo-mechanism to elucidate this degradation was also suggested. Also, the prepared composites were also exploited for energy storage application (supercapacitor). The capacitance of exfoliated sheets centrifuged at 1000 and 500 rpm was measured. . These sheets showed better results due to enhanced surface area. The sheets centrifuged at 500rpm showed superior properties as compared to 1000rpm sheets as enhanced surface area allows higher discharging. It was seen that MoS2/TiO2 composites showed better results for capacitance as compared to pure anatase TiO2.