According to time-dependent density functional theory(TDDFT),we study the interactions between ultra-fast laser pulses and two kinds of calcium titanate quantum dots(PCTO-QDs and MCTO-QDs).Under the action of localize...According to time-dependent density functional theory(TDDFT),we study the interactions between ultra-fast laser pulses and two kinds of calcium titanate quantum dots(PCTO-QDs and MCTO-QDs).Under the action of localized field effect,ultrafast laser can induce quantum dots to make the transition from insulator to metal.The PCTO-QDs are ultimately metallic,while the MCTO-QDs are still insulator after experiencing metal state.This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser.Moreover,laser waveforms approaching to the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface.In this paper,it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser.The importance of local morphology is emphasized by comparing two kinds of CTO-QDs.More importantly,it is an important step to identify the potential properties of perovskite materials.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
In this work,we developed a promising photocatalyst in CsPbBr_(3) quantum dots(QDs)because of their exceptional optoelectronic characteristics.However,QDs applications in the field of photocatalysis were mainly hamper...In this work,we developed a promising photocatalyst in CsPbBr_(3) quantum dots(QDs)because of their exceptional optoelectronic characteristics.However,QDs applications in the field of photocatalysis were mainly hampered by their poor stability and insufficient charge transfer efficiency.Herein,a novel and efficient MnSnO_(2)@CsPbBr_(3)(MSO@QDs)nanocomposite was first time effectively designed and synthe-sized by a wet impregnation method for peroxymonosulfate(PMS)activation under the light.The newly generated interface phase of QDs between MnSnO_(2)(MSO)showed great potential to improve light ab-sorption,leading to effective separation and transfer of photoelectron-hole pairs.This novel nanocompos-ite MSO@QDs showed great Flurbiprofen(FL)removal efficiency under the PMS/Light system.It should be noted that this nanocomposite removed 85.74%of FL in just 70 min,which was almost 1.11 and 2.51 times greater than using pure QDs and pure MSO,respectively.Based on thorough measurements of structural analysis,Brunauer-Emmett-Teller(BET),UV-vis spectra,electrochemical impedance spec-troscopy(EIS),transient photocurrent response,and a potential mechanism for organic pollutants degra-dation over MSO@QDs nanocomposite was envisioned.The principal reactive species of photoinduced holes(h^(+)),i.e.O_(2)^(˙−),SO_(4)^(˙−),^(˙)OH,and non-radical(^(1)O_(2))were characterized via scavengers’technique and electron paramagnetic resonance(EPR)measurements.The highest photocatalytic performance for the re-moval of MO,MB,and IBU was demonstrated by MSO@QDs nanocomposite/PMS,revealing their excellent ability to remove organic pollutants through photo-oxidation.Furthermore,the developed nanocompos-ite exhibited good stability in an aqueous medium.According to computational investigation using the density functional theory(DFT)method,the site’s higher Fukui index f^(0) value corresponds to a greater propensity to be attacked by reactive species.This work offers a fresh perspective on developing further high-efficiency,low-cost photocatalysts for wastewater treatment.展开更多
Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core...Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core–shell materialα-Fe_(2)O_(3)@ZnIn_(2)S_(4)with a step-scheme(S-scheme)heterojunction is synthesized by in situ growth technique,and MXene Ti_(3)C_(2)quantum dots(QDs)are introduced to construct a double-heterojunction tandem mechanism.The photodegradation efficiency ofα-Fe_(2)O_(3)@ZnIn_(2)S_(4)/Ti_(3)C_(2)QDs to bisphenol A is 96.1%and its reaction rate constant attained 0.02595 min^(−1),which is 12.3 times that of pureα-Fe_(2)O_(3).Meanwhile,a series of characterizations analyze the reasons for the enhanced photocatalytic activity,and the charge transport path of the S-scheme heterojunction/Schottky junction tandem is investigated.The construction of the S-scheme heterojunction enables the photo-generated electrons ofα-Fe_(2)O_(3)and the holes of ZnIn2S4 to transfer and combine under the action of the reverse built-in electric field.Due to the metallic conductivity of Ti_(3)C_(2)QDs,the photogenerated electrons of ZnIn_(2)S_(4)are further transferred to Ti_(3)C_(2)QDs to form a Schottky junction,which in turn forms a double-heterojunction tandem mechanism,showing a remarkable charge separation efficiency.This work provides a new opinion for the construction of tandem double heterojunctions to degrade harmful pollutants.展开更多
Perovskite solar cells(PSCs)with a light-harvesting three-dimensional perovskite bulk layer as backbone component have achieved great progress in performance.Nonradiative recombination is one major place to improve ef...Perovskite solar cells(PSCs)with a light-harvesting three-dimensional perovskite bulk layer as backbone component have achieved great progress in performance.Nonradiative recombination is one major place to improve efficiency and stability as they cause significant energy loss in PSCs.Additionally,an imperfection in grain boundaries will initiate device degradation.One of the most successful strategies to decrease nonradiative recombination in PSCs is the introduction of reduced dimensional perovskite(e.g.,perovskite quantum wells),benefiting the device's efficiency and stability tremendously.Here,instead of quantum wells,mixed-cation perovskites with ligand-contained CsPbBr_(x)I_(3−x)quantum dots(QDs)are prepared,which is shown to function as perovskite healing“surface patches.”Benefiting from the“surface patches”effect,the QDs-film shows reduced defects and enhancing film quality which lead to the excellent performance of solar cells(enhancing the power conversion efficiency from 19.21%of the control device to 21.71%[22.1%in reverse scan]).展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant Nos.11974253 and 11774248).
文摘According to time-dependent density functional theory(TDDFT),we study the interactions between ultra-fast laser pulses and two kinds of calcium titanate quantum dots(PCTO-QDs and MCTO-QDs).Under the action of localized field effect,ultrafast laser can induce quantum dots to make the transition from insulator to metal.The PCTO-QDs are ultimately metallic,while the MCTO-QDs are still insulator after experiencing metal state.This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser.Moreover,laser waveforms approaching to the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface.In this paper,it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser.The importance of local morphology is emphasized by comparing two kinds of CTO-QDs.More importantly,it is an important step to identify the potential properties of perovskite materials.
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.
文摘In this work,we developed a promising photocatalyst in CsPbBr_(3) quantum dots(QDs)because of their exceptional optoelectronic characteristics.However,QDs applications in the field of photocatalysis were mainly hampered by their poor stability and insufficient charge transfer efficiency.Herein,a novel and efficient MnSnO_(2)@CsPbBr_(3)(MSO@QDs)nanocomposite was first time effectively designed and synthe-sized by a wet impregnation method for peroxymonosulfate(PMS)activation under the light.The newly generated interface phase of QDs between MnSnO_(2)(MSO)showed great potential to improve light ab-sorption,leading to effective separation and transfer of photoelectron-hole pairs.This novel nanocompos-ite MSO@QDs showed great Flurbiprofen(FL)removal efficiency under the PMS/Light system.It should be noted that this nanocomposite removed 85.74%of FL in just 70 min,which was almost 1.11 and 2.51 times greater than using pure QDs and pure MSO,respectively.Based on thorough measurements of structural analysis,Brunauer-Emmett-Teller(BET),UV-vis spectra,electrochemical impedance spec-troscopy(EIS),transient photocurrent response,and a potential mechanism for organic pollutants degra-dation over MSO@QDs nanocomposite was envisioned.The principal reactive species of photoinduced holes(h^(+)),i.e.O_(2)^(˙−),SO_(4)^(˙−),^(˙)OH,and non-radical(^(1)O_(2))were characterized via scavengers’technique and electron paramagnetic resonance(EPR)measurements.The highest photocatalytic performance for the re-moval of MO,MB,and IBU was demonstrated by MSO@QDs nanocomposite/PMS,revealing their excellent ability to remove organic pollutants through photo-oxidation.Furthermore,the developed nanocompos-ite exhibited good stability in an aqueous medium.According to computational investigation using the density functional theory(DFT)method,the site’s higher Fukui index f^(0) value corresponds to a greater propensity to be attacked by reactive species.This work offers a fresh perspective on developing further high-efficiency,low-cost photocatalysts for wastewater treatment.
基金supported by the National Natural Science Foundation of China(No.21771061)Outstanding Youth Fund of Heilongjiang Province(No.JQ 2020B002).
文摘Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core–shell materialα-Fe_(2)O_(3)@ZnIn_(2)S_(4)with a step-scheme(S-scheme)heterojunction is synthesized by in situ growth technique,and MXene Ti_(3)C_(2)quantum dots(QDs)are introduced to construct a double-heterojunction tandem mechanism.The photodegradation efficiency ofα-Fe_(2)O_(3)@ZnIn_(2)S_(4)/Ti_(3)C_(2)QDs to bisphenol A is 96.1%and its reaction rate constant attained 0.02595 min^(−1),which is 12.3 times that of pureα-Fe_(2)O_(3).Meanwhile,a series of characterizations analyze the reasons for the enhanced photocatalytic activity,and the charge transport path of the S-scheme heterojunction/Schottky junction tandem is investigated.The construction of the S-scheme heterojunction enables the photo-generated electrons ofα-Fe_(2)O_(3)and the holes of ZnIn2S4 to transfer and combine under the action of the reverse built-in electric field.Due to the metallic conductivity of Ti_(3)C_(2)QDs,the photogenerated electrons of ZnIn_(2)S_(4)are further transferred to Ti_(3)C_(2)QDs to form a Schottky junction,which in turn forms a double-heterojunction tandem mechanism,showing a remarkable charge separation efficiency.This work provides a new opinion for the construction of tandem double heterojunctions to degrade harmful pollutants.
基金Hong Kong Polytechnic University,Grant/Award Numbers:1‐CDA5,1‐YWA9,8‐8480Research Grants Council,University Grants Committee,Grant/Award Numbers:15221320,C5037‐18GScience,Technology and Innovation Commission of Shenzhen Municipality,Grant/Award Number:JCYJ20200109105003940。
文摘Perovskite solar cells(PSCs)with a light-harvesting three-dimensional perovskite bulk layer as backbone component have achieved great progress in performance.Nonradiative recombination is one major place to improve efficiency and stability as they cause significant energy loss in PSCs.Additionally,an imperfection in grain boundaries will initiate device degradation.One of the most successful strategies to decrease nonradiative recombination in PSCs is the introduction of reduced dimensional perovskite(e.g.,perovskite quantum wells),benefiting the device's efficiency and stability tremendously.Here,instead of quantum wells,mixed-cation perovskites with ligand-contained CsPbBr_(x)I_(3−x)quantum dots(QDs)are prepared,which is shown to function as perovskite healing“surface patches.”Benefiting from the“surface patches”effect,the QDs-film shows reduced defects and enhancing film quality which lead to the excellent performance of solar cells(enhancing the power conversion efficiency from 19.21%of the control device to 21.71%[22.1%in reverse scan]).
