Extensive study of optical contrast between bulk and nanoscale transition metal dichalcogenide semiconductors

A remarkable refinement in the optical behavior of two-dimensional transition metal dichalcogenides(TMDs)has been brought to light when cleaved from their respective bulks.These atomically thin direct bandgap semiconductors are highly responsive to optical energy which proposes the route for futuristic photonic devices.In this manuscript,we have substantially focused on the optical study of MoS_(2)and WS_(2)nanosheets and comparative analysis with their bulk counterparts.The synthesis of nanosheets has been accomplished with liquid exfoliation followed by fabrication of thin films with drop-casting technique.X-ray diffraction and field emission scanning electron microscopy affirmed the morphology,whereas,UV-visible spectroscopy served as the primary tool for optical analysis.It was observed that several parameters,like optical conductivity,optical band-gap energy etc.have enhanced statistics in the case of exfoliated nanosheets as compared to their respective bulks.Some researchers have touched upon this analysis for MoS_(2),but it is completely novel for WS_(2).We expect our work to clearly distinguish between the optical behaviors of nanoscale and bulk TMDs so as to intensify and strengthen the research related to 2D-layered materials for optoelectronic and photovoltaic applications.

基于葡聚糖自组装胶体粒子的分子印迹传感器的制备及电化学性能

首先,以光敏小分子肉桂酸(CINN)为疏水基元,通过酯化反应对葡聚糖(Dex)进行疏水改性,制备双亲性大分子Dex-CINN;然后,利用选择性溶剂法诱导Dex-CINN与模板分子葡萄糖(Glu)共组装,制备分子印迹胶体粒子(MINPs)。通过红外光谱(FT-IR)和核磁共振氢谱(1 HNMR)确定Dex-CINN的化学结构及改性率。利用Zeta电位及纳米粒度仪和透射电子电镜(TEM)对MINPs的粒径、电位及形貌进行表征。利用滴涂或电泳沉积的方法使MINPs在电极表面二次组装构建MINPs涂层,通过光交联固定涂层结构,再洗脱除去模板分子后得到分子印迹传感涂层。通过扫描电子显微镜(SEM)对两种分子印迹传感涂层的形貌进行表征,并进一步利用循环伏安法(CV)、差分脉冲溶出伏安法(DPSV)对比研究两种分子印迹传感涂层的分析检测性能。研究结果表明:通过滴涂或电泳沉积的方法均能在电极表面制备分子印迹传感涂层;相比于滴涂法,电泳沉积法所制备的分子印迹传感涂层连续均匀,所形成的传感器对Glu具有更好的响应性以及识别能力,检测下限更低。