Generation of Free Carriers in MoSe2 Monolayers Via Energy Transfer from CsPbBr3 Nanocrystals

Transition metal dichalcogenide (TMDCs) monolayers make an excellent component in optoelectronic devices such as photodetectors and phototransistors. Selenide-based TMDCs, specifically molybdenum diselenide (MoSe2) monolayers with low defect densities, show much faster photoresponses compared to their sulfide counterpart. However, the typically low absorption of the atomically thin MoSe2 monolayer and high exciton binding energy limit the photogeneration of charge carriers. Yet, integration of light-harvesting materials with TMDCs can produce increased photocurrents via energy transfer. In this article, it is demonstrated that the interaction of cesium lead bromide (CsPbBr3) nanocrystals with MoSe2 monolayers results into an energy transfer efficiency of over 86%, as ascertained from the quenching and decay dynamics of the CsPbBr3 nanocrystals emission. Notably, the increase in the MoSe2 monolayer emission in the heterostructure accounts only for 33% of the transferred energy. It is found that part of the excess energy generates directly free carriers in the MoSe2 monolayer, as a result of the transfer of energy into the exciton continuum. The efficiency of the heterostructure via enhanced photocurrents with respect to the single material unit is proven. These results demonstrate a viable route to overcome the high exciton binding energy typical for TMDCs, as such having an impact on optoelectronic processes that rely on efficient exciton dissociation

Examining queue-jumping phenomenon in heterogeneous traffic stream at signalized intersection using UAV-based data

© 2020, Springer-Verlag London Ltd., part of Springer Nature. This research presents an in-depth microscopic analysis of heterogeneous and undisciplined traffic at the signalized intersection. Traffic data extracted from the video recorded using an unmanned aerial vehicle (UAV) at an approach of a signalized intersection is analyzed to study the within green time dynamics of traffic flow. Various parameters of Wiedemann 74, Wiedemann 99, and lateral behavior models used in microscopic traffic simulation package, Vissim, are calibrated for the local heterogeneous traffic. This research is aimed at exploring the queue-jumping phenomenon of motorbikes at signalized intersections and its impact on the saturation flow rate, travel time, and delay. The study of within green time flow dynamics shows that the flow of traffic within green time is not uniform. Surprisingly, the results indicate that the traffic flow for the first few seconds of the green time is significantly higher than the remaining period of green time, which shows a contradiction to the fact that traffic flow for the first few seconds is lower due to accelerating vehicles. Mode-wise traffic counted per second shows that this anomaly is attributed to the presence of motorbikes in front of the queue. Consequently, the outputs of simulation results obtained from calibrated Vissim show that the simulated travel time for motorbikes is significantly lower than the field-observed travel times even though the average simulated traffic flow matches accurately with the field-observed traffic flow. The findings of this research highlight the need to incorporate the queue-jumping behavior of motorbikes in the microsimulation packages to enhance their capability to model heterogeneous and undisciplined traffic

An eco-friendly non-conventional adsorbent from silk cotton fiber for the removal of methylene blue dye

497-505Highly porous activated carbon fiber with excellent surface area has been prepared using silk cotton fiber as a precursor. The Activated Silk Cotton Fiber (ASC) has well developed porosity with rose flower like structure. The BET surface area of the prepared adsorbent is 1041.08 m2/g with a total pore volume of 0.4944 cm3/g. The adsorption capability of the prepared adsorbent ASC has been analyzed using methylene blue (MB) dye. The effect of pH indicates that ASC has its maximum adsorption at a pH of 10. On analyzing the kinetics of MB adsorption, the pseudo-second order kinetic model describes the adsorption with good r2 value of 0.9895 2 < 0.9997. The maximum Langmuir monolayer adsorption capacity is found to be 80.65 mg/g at 45°C. The experimental results and the thermodynamic studies prove the physisorption nature of MB adsorption onto ASC

Continuous fixed bed adsorption studies of Rhodamine-B dye using polymer bound adsorbent

53-58<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:"times="" roman";letter-spacing:-.1pt;mso-ansi-language:="" en-gb;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-GB">An eco-friendly adsorbent is developed by coating polyaniline over an activated carbon prepared from the seeds of Prosopis Juliflora using ZnCl2 as an activating agent (PPAC). The polymer bound adsorbent has good adsorption characteristics with a surface area of 1028 m2/g. A continuous flow fixed bed study is carried out by using PPAC as an adsorbent packed in a column for the removal of Rhodamine-B dye from aqueous solution. The effect of operating parameters such as flow rate, bed height and inlet dye concentration on the sorption characteristics of RB <span style="font-size:11.0pt; mso-bidi-font-size:10.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-bidi-font-family:times-roman;letter-spacing:-.1pt;="" mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:ta"="" lang="EN-GB">have been investigated at room temperature (30°C) and the natural pH of dye solution. On increasing the influent concentration from 25 to 75 mg/L, the volume of effluent treated decreases from 3800 to 2950 mL. The kinetic models suggested by Bohart-Adam, Thomas and Yoon-Nelson are employed to study this adsorption system. The YN model fits exceptionally well for the adsorption of RB onto PPAC with respect to all of the calculated parameters with high correlation coefficient (0.9431 to 0.9668) and low standard deviation (0.04 to 0.75). </span