Transient Absorption Analysis on Energy Transfer from Carbon Quantum Dots to Tungsten Disulfide

The combination of carbon quantum dots (CQDs) with transition metal disulfides results in 0D–2D composites with enhanced light absorption properties. In the transient absorption spectrum of CQD–WS2 composites, photoinduced absorption feature of the intrinsic state was inhibited by WS2. The suppressed photoinduced absorption feature of the defect state appeared at a particular WS2 concentration (0.1–0.13 mg/mL), which indicates that the capture ability of the defect state is enhanced by WS2. Transient absorption spectrum reveals the energy transfer dynamics from intrinsic and defect states of CQDs to WS2. Energy transfer efficiency can reach up to 92% at 0.2 mg/mL WS2. The understanding and manipulation of energy transfer dynamics in 0D–2D composites has made great contributions in optical devices

Assessing the Depositional Environment of Cretaceous Ge-Rich Coals in the Wulantuga Mine, Shengli Coalfield, Northeastern China

To provide a new perspective on the formation of the Ge-rich coals, the depositional environment of the Wulantuga coals was studied with the incorporation of coal maceral and geochemistry-based indicators. The results show that the No.6 coal seam in the Wulantuga mine was formed in a mire with a succession of swamps, fens, and marsh. The average contents of Ge in coals formed in different mires, from high to low, are swamp (220 μg/g), marsh (205 μg/g), and fen (185 μg/g). The accumulation of the No.6 seam has been divided into four stages from bottom to top based on the identified coal facies types. The reducing condition and gelification of the ecosystem environment ranged from strong to weak, to strong, and back to weak. The variation of Ge concentrations also occurs in the same way. Strong reduction and gelification of the ecosystem environments can favor Ge enrichments in the Wulantuga coals. Sufficient sources and favorable conditions are essential for the unusual Ge enrichments in coals. This study provides a new perspective for the depositional environment of Ge-rich coals and is useful for the exploration of Ge-rich coal resources