A novel series of Mn^(4+)and Eu^(3+)co-doped double-perovskite Ca_(2)ScNbO_(6)(CSNO)phosphor was synthesized in this work.The phase structure and photoluminescence properties were systematically researched.Due to the ...A novel series of Mn^(4+)and Eu^(3+)co-doped double-perovskite Ca_(2)ScNbO_(6)(CSNO)phosphor was synthesized in this work.The phase structure and photoluminescence properties were systematically researched.Due to the different thermal quenching properties of Mn^(4+)and Eu^(3+)ions,a dual-mode temperature measurement technique over a wide temperature range was established.The CSNO phosphor co-doped with Mn^(4+)and Eu^(3+)ions has a self-calibrated effect due to the different thermal quenching effects of Mn^(4+)and Eu^(3+)ions.The maximum relative sensitivity(S_(R1,R2))values of the CSNO:0.1 mol%Mn^(4+)/0.5 mol%Eu^(3+)phosphor are determined to be 1.92%/K and 1.76%/K at 523 K,under excitation at 296 and 396 nm,respectively.Additionally,the temperature-dependent lifetime of Mn^(4+)indicates that the maximum S_(R3,R4) values for the synthesized phosphors are 1.669%/K(λ_(ex)=296 nm)and1.664%/K(λ_(ex)=396 nm),re spectively.It is interesting to note that different SRcan be obtained by varying the excitation wavelength to the CSNO:0.1 mol%Mn^(4+)/0.5 mol%Eu^(3+)phosphor.Ultimately,this work provides a reference for the development of highly sensitive fluorescent materials based on dualemitting centers of double-perovskite.展开更多
Recent years have seen a surge in the use of low-dimensional transition metal dichacolgenides,such as MoS_(2),as catalysts for the electrochemical hydrogen evolution reaction.In particular,sulfur vacancies in MoS_(2)c...Recent years have seen a surge in the use of low-dimensional transition metal dichacolgenides,such as MoS_(2),as catalysts for the electrochemical hydrogen evolution reaction.In particular,sulfur vacancies in MoS_(2)can activate the inert basal plane,but that requires an unrealistically high defect concentration(~9%)to achieve optimal activity.In this work,we demonstrate by firstprinciples calculations that assembling van der Waals heterostructures can enhance the catalytic activity of MoS_(2)with low concentrations of sulfur vacancies.We integrate MoS_(2)with various two-dimensional nanostructures,including graphene,h-BN,phosphorene,transition metal dichacolgenides,MXenes,and their derivatives,aiming to fine-tune the free energy of atomic hydrogen adsorption.Remarkably,an optimal free energy can be achieved for a low sulfur vacancy concentration of~2.5%in the MoS_(2)/MXene-OH heterostructure,as well as high porosity and tunability.These results demonstrate the potential of combining two-dimensional van der Waals assembly with defect engineering for efficient hydrogen production.展开更多
基金Project supported by National Natural Science Foundation of China(12004062)Natural Science Foundation of Chongqing(CSTB2024NSCQLZX0030)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-M202300601,KJZD-K202300612,KJQN202300613)Venture and Innovation Support Program for Chongqing Overseas Returnees(CX2019085,CX2022024)。
文摘A novel series of Mn^(4+)and Eu^(3+)co-doped double-perovskite Ca_(2)ScNbO_(6)(CSNO)phosphor was synthesized in this work.The phase structure and photoluminescence properties were systematically researched.Due to the different thermal quenching properties of Mn^(4+)and Eu^(3+)ions,a dual-mode temperature measurement technique over a wide temperature range was established.The CSNO phosphor co-doped with Mn^(4+)and Eu^(3+)ions has a self-calibrated effect due to the different thermal quenching effects of Mn^(4+)and Eu^(3+)ions.The maximum relative sensitivity(S_(R1,R2))values of the CSNO:0.1 mol%Mn^(4+)/0.5 mol%Eu^(3+)phosphor are determined to be 1.92%/K and 1.76%/K at 523 K,under excitation at 296 and 396 nm,respectively.Additionally,the temperature-dependent lifetime of Mn^(4+)indicates that the maximum S_(R3,R4) values for the synthesized phosphors are 1.669%/K(λ_(ex)=296 nm)and1.664%/K(λ_(ex)=396 nm),re spectively.It is interesting to note that different SRcan be obtained by varying the excitation wavelength to the CSNO:0.1 mol%Mn^(4+)/0.5 mol%Eu^(3+)phosphor.Ultimately,this work provides a reference for the development of highly sensitive fluorescent materials based on dualemitting centers of double-perovskite.
基金This work was supported by the National Natural Science Foundation of China(11674042)the Science Challenge Project(TZ2018004)+1 种基金the Fundamental Research Funds for the Central Universities(106112016CDJXY120001)the Thousand Youth Talents Program of China.
文摘Recent years have seen a surge in the use of low-dimensional transition metal dichacolgenides,such as MoS_(2),as catalysts for the electrochemical hydrogen evolution reaction.In particular,sulfur vacancies in MoS_(2)can activate the inert basal plane,but that requires an unrealistically high defect concentration(~9%)to achieve optimal activity.In this work,we demonstrate by firstprinciples calculations that assembling van der Waals heterostructures can enhance the catalytic activity of MoS_(2)with low concentrations of sulfur vacancies.We integrate MoS_(2)with various two-dimensional nanostructures,including graphene,h-BN,phosphorene,transition metal dichacolgenides,MXenes,and their derivatives,aiming to fine-tune the free energy of atomic hydrogen adsorption.Remarkably,an optimal free energy can be achieved for a low sulfur vacancy concentration of~2.5%in the MoS_(2)/MXene-OH heterostructure,as well as high porosity and tunability.These results demonstrate the potential of combining two-dimensional van der Waals assembly with defect engineering for efficient hydrogen production.
