Electrochemically induced Fenton (electro-Fenton) reaction was used for efficient and controllable preparation of hydroxyl radicals, leading to the generation of luminescent quantum dots through etching of as-exfoliated MoS2 nanosheets. Morphologic changes of MoS2 nanosheets during the electro-Fenton reaction were monitored using transmission electron microscopy, showing that etching of MoS2 nanosheets induced by hydroxyl radicals resulted in rapid homogeneous fracturing of the sheets into small dots via a transition of nanoporous morphology. The as-generated dots with vertical dimensional thickness of ca. 0.7 nm and plane size of ca. 5 nm were demonstrated to be MoS2 quantum dots (MoS2-QDs), and their photoluminescence properties were explored based on quantum confinement, edge effect, and intrinsic characteristics. Moreover, the degree of etching and the concomitant porosity of MoS2 nanosheets could be conveniently tuned via the electro-Fenton reaction time, resulting in a new morphology of nanoporous MoS2 nanosheets, with potential new applications in various significant areas.

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Single factor water quality identification index (SFWQII) and Comprehensive water quality identification index (CWQII) were applied to the data of 6 parameters for water quality of West Lake at 10 different sites and 4 main inflows in the West Lake basin, generated during March 2012 to February 2013. This study evaluated and elucidated the temporal and spatial variation of each parameter on water quality and the main pollution factor of West Lake by SFQII. CWQII based on the SFQII was applied to evaluate the eutrophication level of West Lake and substantiated mesotrophic waters. Stable isotopes of nitrate were used to identify the nitrate sources of West Lake. The δ15NNO3 values in samples from the West Lake and inflows had a range of 2.6‰ to 12.0‰, while the δ15NNO3 values in Qiantang River was 5.3‰, in rainfall was 5.2‰ and in runoff was 3.6‰, respectively. Animal wastes, commercial fertilizer and domestic sewage were the main nitrate sources. The groundwater and denitrification might increase the levels of NO3- in West Lake.