Photocatalytic Activity of MWCNT-Reinforced MoS2 Nanosheets

Abstract

Two-dimensional transition metal dichalcogenides, especially MoS₂, are widely exploited for their proficiency owing to the optimum energy band gap required for photocatalytic mechanism. However, the electron–hole pair recombination hampers the photocatalytic efficiency of pristine 2D MoS₂. In this work, multi-walled carbon nanotubes (MWCNTs) are reinforced into 2D MoS₂ nanosheets via an ultrasound-driven liquid exfoliation technique to synthesize an efficient photocatalyst. The resulting composite nanosheets are characterized structurally by high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The ultraviolet–visible (UV–vis) absorption and photoluminescence spectroscopy reveal changes in the band gap and the recombination rate probability of the photogenerated charge carriers, respectively. The photocatalytic performance of the composite nanosheets is investigated by photodegradation of methylene blue dye. The efficiency of the photocatalysts is studied for varying concentrations of the reinforcement. The values of rate constant (at 665 nm) are 0.0047 min⁻¹ for pristine MoS₂ nanosheets, 0.0171 min⁻¹, 0.0177 min⁻¹, and 0.0183 min⁻¹ for MoS₂@MWCNT composite nanosheets of 2%, 4%, and 8% of MWCNT, respectively. The degradation percentage is 60%, 84%, 85%, and 86% for pristine MoS₂, MoS₂@MWCNT composite nanosheets of 2%, 4%, and 8% of MWCNT, respectively. The results of the study show the enhanced degradation efficiency of the MoS₂@MWCNT composite nanosheets in comparison to pristine MoS₂ nanosheets. Consequently, this work suggests an alternate hybrid of MoS₂ with MWCNTs synthesized via a rapid, easy, cost-effective, and efficient route for superior degradation efficiency, which can be beneficial for engineering hybrid structures of MoS₂ -based photocatalysts with promising potential for photocatalytic activities.