The effect of deposition temperature on the morphology and optoelectronic performance of Ge/Si QDs grown by magnetron sputtering under low Ge deposition(~4 nm)was investigated by atomic force microscopy,Raman spectroscopy,and photoluminescence(PL)tests.The experimental results indicate that temperatures higher than 750℃effectively increase the crystallization rate and surface smoothness of the Si buffer layer,and temperatures higher than 600℃significantly enhance the migration ability of Ge atoms,thus increasing the probability of Ge atoms meeting and nucleating to form QDs on Si buffer layer,but an excessively high temperature will cause the QDs to undergo an Ostwald ripening process and thus develop into super large islands.In addition,some PL peaks were observed in samples containing small-sized,high-density Ge QDs,the photoelectric properties reflected by these peaks were in good agreement with the corresponding structural characteristics of the grown QDs.Our results demonstrate the viability of preparing high-quality QDs by magnetron sputtering at high deposition rate,and the temperature effect is expected to work in conjunction with other controllable factors to further regulate QD growth,which paves an effective way for the industrial production of QDs that can be used in future devices.
鉴于四环素类抗生素大量使用造成的环境污染以及人体肝损伤、肠道功能紊乱和过敏等不良反应,亟需开发一种灵敏度高、操作简便、价格低廉的四环素类抗生素残留检测方法。荧光法具有操作简单、成本低廉、可视化等优点,因此,本工作基于MXene QDs和铕离子构建了可选择性检测强力霉素(DOX)的比率荧光探针。以尿酸和单层Ti3CN为原料通过水热法制备得MXene QDs,MXene QDs与Eu3+通过自组装构建得到MXene QDs-Eu3+双发射荧光探针,用于DOX的选择性检测。并通过优化探针体系中的MXene QDs浓度、Eu3+浓度、pH和响应时间等实验条件,探究该双发射荧光探针对强力霉素的定量和选择性检测性能。结果表明,该荧光探针对DOX具有特异性识别能力,且荧光强度比(F615/F421)与不同浓度DOX (0∼30 μM)之间存在良好的线性关系,表明其在TCs残留检测中具有良好应用前景。Given the environmental pollution, liver damage, intestinal dysfunction, and allergic reactions caused by the extensive use of tetracycline antibiotics, there is an urgent need to develop a sensitive, simple, and cost-effective method for detecting residual tetracycline antibiotics. The fluorescence method possesses advantages such as simple operation, low cost, and visualizability. Therefore, this work constructs a ratio fluorescence probe for the selective detection of doxycycline based on MXene QDs and rare earth ions. We prepared MXene QDs using uric acid and single-layer Ti3CN as raw materials through a hydrothermal method. The MXene QDs-Eu3+ dual-emission fluorescent probe was constructed by self-assembly of MXene QDs and Eu3+, which was used for the selective detection of streptomycin. By optimizing the experimental conditions such as the concentration of MXene QDs, Eu3+, pH, and response time in the probe system, this dual-emission fluorescent probe was explored for quantitative and selective detection of streptomycin. Findings show that the fluoresce
Exploring high efficiency S-scheme heterojunction photocatalysts with strong redox ability for removing volatile organic compounds from the air is of great interest and importance.However,how to predict and regulate the transport of photogenerated carriers in heterojunctions is a great challenge.Here,density functional theory calculations were first used to successfully predict the formation of a CdS quantum dots/InVO_(4)atomic-layer(110)/(110)facet S-scheme heterojunction.Subsequently,a CdS quantum dots/InVO_(4)atomic-layer was synthesized by in-situ loading of CdS quantum dots with(110)facets onto the(110)facets of InVO_(4)atomic-layer.As a result of the deliberately constructed built-in electric field between the adjoining facets,we obtain a remarkably enhanced photocatalytic degradation rate for ethylene.This rate is 13.8 times that of pure CdS and 13.2 times that of pure InVO_(4).In-situ irradiated X-ray photoelectron spectroscopy,photoluminescence and time-resolved photoluminescence measurements were carried out.These experiments validate that the built-in electric field enhanced the dissociation of photoexcited excitons and the separation of free charge carriers,and results in the formation of S-scheme charge transfer pathways.The reaction mechanism of the photocatalytic C_(2)H_(4)oxidation is investigated by in-situ electron paramagnetic resonance.This work provides a mechanistic insight into the construction and optimization of semiconductor heterojunction photocatalysts for application to environmental remediation.
