Size-dependent optical properties of MoS₂ nanoparticles and their photo-catalytic applications

Abstract

While two-dimensional (2D) layered MoS2 nanosheets have been extensively studied owing to their fascinating optoelectronic properties, less attention has been paid to the corresponding zero-dimensional nano-crystals. In this contribution, we report the efficacy of MoS2 nanocrystals for their size tunable properties for optical and photocatalytic applications. We have synthesized differently sized (10–70 nm) crystalline, hexagonal 2H-MoS2 nanoparticles (NPs) dispersed in DMF solvent using a simple exfoliation technique. Synthesized NPs are found to exhibit size-dependent optical properties and excitation-dependent fluorescence characteristics in the visible region, which are otherwise not observed in bulk or 2D MoS2 layers. Size tunable bandgap and broad absorbance and emission spectrum covering the visible range could be exploited in the fabrication of various opto-electronic devices. Charge carrier emission dynamics of differently sized MoS2 NPs are investigated using time correlated single photon counting (TCSPC) spectroscopic technique. We found two time components, one in the order of several hundreds of ps, which arises due to the radiative recombination of charge carriers, while the other one is of the order of a few ns, which emanates from the defect states of MoS2 NPs. The average time constants are found to decrease with increase in particle size. A noticeable photocatalytic activity of the synthesized MoS2 NPs under visible light illumination for the degradation of brilliant green dye is also demonstrated for the first time and the effect of size variation of NPs in the dye degradation process is reported.

Tuning the photocatalytic/electrocatalytic properties of MoS2/MoSe2 heterostructures by varying the weight ratios for enhanced wastewater treatment and hydrogen production

“…The lower energy PL emission can be ascribed to the transition between quantized energy levels and the other peak is might be due to defect state mediated transition. 27,28 The PL intensity of all the composites prepared was lower than the pure MoSe 2 which indicates that the photocatalytic activity of the composites is higher as compared to individual components because of the higher separation efficiency of the photo-induced charges in the composites. 004), ( 006), ( 102), ( 111), ( 105), ( 201), ( 110), ( 103), ( 200) and (203) (hkl) planes respectively (JCPDS le no 77-1715) and intensity of these peaks increases as the amount of MoSe 2 in the composite increases.…”

Synthesis of Anatase/Brookite Mixed Phase TiO2 Nanostructures and its Photocatalytic Performance Study

“…[14][15][16][17][18][19][20] Over the past twothree decades, the use of nanostructured semiconductor materials, especially TiO 2 , ZnO, SnO 2 , ZnS, SnS 2 , MoS 2 , CdS, CeO 2 , Fe 2 O 3 , Ta 2 O 5 , WO 3 , Nb 2 O 5 , SrTiO 3 and many more, has been utilized as potential photocatalysts. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Amongst the reported semiconductor oxides and sulfides, TiO 2 is the most studied photocatalyst due to its chemical and biologically stable nature, cost effective, having optimum band gap and band positions with stronger reducing and oxidizing electronsholes respectively. Additionally, titanium dioxide (TiO 2 ) is a semiconductor oxide exists in three crystalline phases i. e. anatase, rutile, and brookite with an excellent photocatalytic property having direct band gap of 3.2, 3.0 and 3.4 eV respectively.…”

MoS2 Nanosheets with Narrowest Excitonic Line Widths Grown by Flow-Less Direct Heating of Bulk Powders: Implications for Sensing and Detection

“…60,61 These properties turn 2D-MoS 2 into an ideal laboratory for exploring many-body phenomena, and a highly tunable and prime candidate for a wide range of applications such as photoemitters, phototransistors, and photodetectors. [62][63][64][65][66][67][68][69][70][71][72][73] Excited-state dynamics in monolayer TMDs is sensitive to their quality, and their relaxation pathways are affected both intrinsic (e.g. e-e, e-phonon interactions) and extrinsic (e.g.…”