Synergistic Effect of Yb3+, Tm3+, Nd3+ Doped NaYF4 Nanoparticles and MoS2 Nanosheets for Enhanced Photocatalytic Dye Degradation under Visible Light

The synergistic influence of synthesized MoS2 (syn-MoS2) nanosheets and NaYF4:Yb,Tm,Ndupconversion nanoparticles (UCNP) on effective dye degradation isdemonstrated. A detailed characterization of bulk MoS2 (b-MoS2), syn-MoS2 (with enhanced photocatalytic activity compared to the commerciallyavailable b-MoS2), and UCNP was done.Optical properties revealed that emission spectra of UCNP correspondingto 450, 475, and 650 nm overlap with absorption spectra of MoS2 (similar to 455 and 635 nm). A comparative methylene blue degradationof 96% could be achieved with the combination of UCNP and syn-MoS2 in comparison to 56.4% for syn-MoS2 and 42% for b-MoS2.Concentration-dependent dye degradation study of UCNP and syn-MoS2 revealed a maximum dye removal efficiencyof 99.6% for 150 mg L-1 of syn-MoS2 and 200 mg L-1 of UCNP within 2 hrs. Comparativedegradation investigations were performed on various dyes (methyleneblue, methylene orange, rhodamine B, and their mixture) and watersystems (artificial river-water and artificial seawater) to assessthe potential applicability of the system in environmental remediation.After five cycles of reusability studies, an efficacy of 88% dye removalwas obtained. The mechanism behind this was investigated using theESR and scavengers test, which confirmed that the primary radicalsresponsible for dye degradation were superoxide (O-center dot(2) (-)) and hydroxyl ((OH)-O-center dot). A comparative photocurrent experiment also verified that thepresence of UCNP enhances the efficiency of the syn-MoS2 by 98% in the presence of visible light.

Automated summary

The synergistic effect of synthesized MoS2 nanosheets and NaYF4:Yb,Tm,Nd upconversion nanoparticles (UCNP) on effective dye degradation is demonstrated. The optical properties show that the emission spectra of UCNP overlap with the absorption spectra of MoS2. The combination of UCNP and syn-MoS2 achieves 96% degradation of methylene blue, compared to 56.4% for syn-MoS2 alone and 42% for b-MoS2. Concentration-dependent dye degradation studies reveal a maximum removal efficiency of 99.6% with 150 mg L-1 of syn-MoS2 and 200 mg L-1 of UCNP within 2 hours.