Constructing heterostructures with narrow-band-gap semiconductors is a promising strategy to extend light absorption range of graphitic carbon nitride(g-C_(3)N_(4))and simultaneously promote charge separation for its ...Constructing heterostructures with narrow-band-gap semiconductors is a promising strategy to extend light absorption range of graphitic carbon nitride(g-C_(3)N_(4))and simultaneously promote charge separation for its photocatalytic activity improvement.However,its highly localized electronic states of g-C_(3)N_(4)hinder photo-carrier migration through bulk towards heterostructure interfaces,resulting in low charge carrier separation efficiency of solid bulk g-C_(3)N_(4)-based heterostructures.Herein,porous g-C_(3)N_(4)(PCN)material with greatly shortened migration distance of photo-carriers from bulk to surface was used as an effective substrate to host Cd Se quantum dots to construct type II heterostructure of Cd Se/PCN for photocatalytic hydrogen production.The homogeneous modification of the Cd Se quantum dots throughout the whole bulk of PCN together with proper band alignments between Cd Se and PCN enables the effective separation of photo-generated charge carriers in the heterostructure.Consequently,the Cd Se/PCN heterostructure photocatalyst gives the greatly enhanced photocatalytic hydrogen production activity of192.3μmol h^(-1),which is 4.4 and 8.1 times that of Cd Se and PCN,respectively.This work provides a feasible strategy to construct carbon nitride-based heterostructure photocatalysts for boosting visible light driven water splitting performance.展开更多
To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction met...To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction method,CdSe and A1 were respectively packaged on the surface of CsPbBr_(3)QDs to form the core-shell CsPbBr_(3)/CdSe/Al QDs.After one week in a natural environment,the photoluminescence quantum yields of CsPbBr_(3)/CdSe/Al QDs were greater than 80%,and the PL intensity remained at 71%of the original intensity.Furthermore,the CsPbBr_(3)/CdSe/Al QDs were used as green emitters for white light-emitting diodes(LEDs),with the LEDs spectrum covering 129%of the national television system committee(NTSC)standard color gamut.The core-shell structure of QDs can effectively improve the stability of CsPbBr_(3)QDs,which has promising prospects in optoelectronic devices.展开更多
Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with tho...Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with those in the conventional nanomaterial synthesis. However, the manipulation and control of nanomaterial biosynthesis remain difficult because of the lack of knowledge about the biosynthetic mechanisms. In the present study, we elucidated the selenium （Se）-precursor and Se metabolic flux in the biosynthesis of cadmium-selenium quantum dots （CdSe QDs） in Saccharomyces cerevisiae and improved the cells＇ ability to biosynthesize CdSe QDs through gene modification based on the regulation mechanism. By deleting the genes involved in Se metabolism and measuring seleno-amino acids, we identified selenocysteine （SeCys） as the primary Se-precursor in the intracellular biosynthesis of CdSe QDs. Further studies demonstrated that the selenomethionine （SeMet）-to-SeCys pathway regulates CdSe QD biosynthesis. Knowledge of the regulatory pathway allowed us to enhance SeMet synthesis by overexpression of the MET6 gene, and an increased CdSe QD yield was realized in the engineered cells. Understanding the mechanism of CdSe QD biosynthesis helped to determine the relationship between nanocrystal formation and biological processes, and offers a new perspective to manipulation of nanomaterial biosynthesis.展开更多
Biological synthesis of quantum dots （QDs） as an environmental-friendly and facile preparation method has attracted increasing interests. However, it is difficult to distinguish the roles ofbio-thiols in QDs synthes...Biological synthesis of quantum dots （QDs） as an environmental-friendly and facile preparation method has attracted increasing interests. However, it is difficult to distinguish the roles ofbio-thiols in QDs synthesis process because of the complex nature in organisms. In this work, the CdSe QDs synthesis conditions in organisms were reconstructed by using a simplified in vitro approach to uncover the roles of two small bio-thiols in the QDs formation. CdSe QDs were synthesized with glutathione （GSH） and L-cysteine （Cys） respectively. Compared with Cys at the same molar concentration, the CdSe QDs synthesized by GSH had a larger and broader particle size distribution with improved optical properties and crystal structure. Furthermore, quantum chemical calculations indicate that the stronger Cd^2＋ binding capacity ofGSH contributed a lot to the CdSe QDs formation despite ofthe greater capability Cys for selenite reduction. This work clearly demonstrates the different roles of small thiols in the Cd2^＋- stabilization in the environment and biomimetic QDs synthesis process.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52002377,51825204 and 21633009)the China Postdoctoral Science Foundation(Nos.2020M681003 and 2020TQ0327)the Natural Science Foundation of Liaoning Province(No.2020BS009)。
文摘Constructing heterostructures with narrow-band-gap semiconductors is a promising strategy to extend light absorption range of graphitic carbon nitride(g-C_(3)N_(4))and simultaneously promote charge separation for its photocatalytic activity improvement.However,its highly localized electronic states of g-C_(3)N_(4)hinder photo-carrier migration through bulk towards heterostructure interfaces,resulting in low charge carrier separation efficiency of solid bulk g-C_(3)N_(4)-based heterostructures.Herein,porous g-C_(3)N_(4)(PCN)material with greatly shortened migration distance of photo-carriers from bulk to surface was used as an effective substrate to host Cd Se quantum dots to construct type II heterostructure of Cd Se/PCN for photocatalytic hydrogen production.The homogeneous modification of the Cd Se quantum dots throughout the whole bulk of PCN together with proper band alignments between Cd Se and PCN enables the effective separation of photo-generated charge carriers in the heterostructure.Consequently,the Cd Se/PCN heterostructure photocatalyst gives the greatly enhanced photocatalytic hydrogen production activity of192.3μmol h^(-1),which is 4.4 and 8.1 times that of Cd Se and PCN,respectively.This work provides a feasible strategy to construct carbon nitride-based heterostructure photocatalysts for boosting visible light driven water splitting performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.61865002 and 62065002)Project of Outstanding Young Scientific and Technological Talents of Guizhou Province,China(Grant No.QKEPTRC[2019]5650)+1 种基金Guizhou Province Science and Technology Platform and Talent Team Project,China(Grant No.QKEPTRC[2018]5616)Central Government of China Guiding Local Science and Technology Development Plan(Grant No.QKZYD[2017]4004)。
文摘To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction method,CdSe and A1 were respectively packaged on the surface of CsPbBr_(3)QDs to form the core-shell CsPbBr_(3)/CdSe/Al QDs.After one week in a natural environment,the photoluminescence quantum yields of CsPbBr_(3)/CdSe/Al QDs were greater than 80%,and the PL intensity remained at 71%of the original intensity.Furthermore,the CsPbBr_(3)/CdSe/Al QDs were used as green emitters for white light-emitting diodes(LEDs),with the LEDs spectrum covering 129%of the national television system committee(NTSC)standard color gamut.The core-shell structure of QDs can effectively improve the stability of CsPbBr_(3)QDs,which has promising prospects in optoelectronic devices.
基金This work was supported by the National Natural Science Foundation of China （NSFC） （Nos. 21272182 and 31570090） and the National Basic Research Program of China （973 Program） （No. 2013CB933904）. This project is partially supported by the Chinese 111 Project （No. B06018）, the National Infrastructure of Natural Resources for Science and Technology Program of China （No. NIMR-2017-8）, the National Fund for Fostering Talents in Basic Sciences （No. J1103513）, and the Laboratory （Innovative） Research Fund of Wuhan University. We are grateful to Prof. Yang Wenchao for his generous gift of Probe 3.
文摘Currently, the biosynthesis of nanomaterials by organisms is attracting considerable attention because of the sustainable and environmentally friendly nature of the reactions involved in this process compared with those in the conventional nanomaterial synthesis. However, the manipulation and control of nanomaterial biosynthesis remain difficult because of the lack of knowledge about the biosynthetic mechanisms. In the present study, we elucidated the selenium （Se）-precursor and Se metabolic flux in the biosynthesis of cadmium-selenium quantum dots （CdSe QDs） in Saccharomyces cerevisiae and improved the cells＇ ability to biosynthesize CdSe QDs through gene modification based on the regulation mechanism. By deleting the genes involved in Se metabolism and measuring seleno-amino acids, we identified selenocysteine （SeCys） as the primary Se-precursor in the intracellular biosynthesis of CdSe QDs. Further studies demonstrated that the selenomethionine （SeMet）-to-SeCys pathway regulates CdSe QD biosynthesis. Knowledge of the regulatory pathway allowed us to enhance SeMet synthesis by overexpression of the MET6 gene, and an increased CdSe QD yield was realized in the engineered cells. Understanding the mechanism of CdSe QD biosynthesis helped to determine the relationship between nanocrystal formation and biological processes, and offers a new perspective to manipulation of nanomaterial biosynthesis.
基金Acknowledgements The work was supported by the National Natural Science Foundation of China （Grant No. 21590812）, and the Collaborative Innovation Center of Suzhou Nano Science and Technology.
文摘Biological synthesis of quantum dots （QDs） as an environmental-friendly and facile preparation method has attracted increasing interests. However, it is difficult to distinguish the roles ofbio-thiols in QDs synthesis process because of the complex nature in organisms. In this work, the CdSe QDs synthesis conditions in organisms were reconstructed by using a simplified in vitro approach to uncover the roles of two small bio-thiols in the QDs formation. CdSe QDs were synthesized with glutathione （GSH） and L-cysteine （Cys） respectively. Compared with Cys at the same molar concentration, the CdSe QDs synthesized by GSH had a larger and broader particle size distribution with improved optical properties and crystal structure. Furthermore, quantum chemical calculations indicate that the stronger Cd^2＋ binding capacity ofGSH contributed a lot to the CdSe QDs formation despite ofthe greater capability Cys for selenite reduction. This work clearly demonstrates the different roles of small thiols in the Cd2^＋- stabilization in the environment and biomimetic QDs synthesis process.
