Inorganic black-phase CsPbI_(3)perovskites(cubicα,tetragonalβand orthorhombicγ)have attracted immense attention due to their superior optical and optoelectronic properties.However,the black phase is metastable and ...Inorganic black-phase CsPbI_(3)perovskites(cubicα,tetragonalβand orthorhombicγ)have attracted immense attention due to their superior optical and optoelectronic properties.However,the black phase is metastable and spontaneously transforms into a non-optically active yellow phase(orthorhombicδ)as the temperature drops to room temperature or even lower.This severely inhibits its practical applications under light and driving voltage,and at varying temperatures.Here,we report a novel method to improve the stability ofγ-CsPbI_(3)nanowires in a wide temperature range.With an ordered mesoporous silica SBA-15 template,the CsPbI_(3)nanowires are confined into the channels and crystalize in theδphase,which can transform into theγphase under calcination at 623 K.Compared with the CsPbI_(3)obtained without SBA-15,theseγ-CsPbI_(3)nanowires are stable until 193 K,the lowest temperature record to date.The phase stability stems from the interfacial coordination of Pb and O,which acts as an“anchor”to suppress the distortion of the[PbI_(6)]^(4)−octahedron forγ-CsPbI_(3).Additionally,this protocol can be extended to mixed halide perovskites.The“anchor”in this work is also expected to shed light on intriguing studies on the phase stabilization of other functional materials.展开更多
As a promising visible-light-responsive catalyst,graphitic carbon nitride(g-C_(3)N_(4))has been widely used in environmental and energy applications owing to its unique semiconducting optoelectronic properties.However...As a promising visible-light-responsive catalyst,graphitic carbon nitride(g-C_(3)N_(4))has been widely used in environmental and energy applications owing to its unique semiconducting optoelectronic properties.However,the photocatalytic performance of bulk g-C_(3)N_(4)synthesized using N-containing precursors via a conventional thermal polycondensation process is generally limited by low crystallinity caused by incomplete polymerization.In addition to forced polymerization under high-pressure conditions,removing the unpolymerized and inactive part of bulk g-C_(3)N_(4)through controllable etching is another practical way to optimize its crystallinity.Therefore,we developed an economical and general method to fabricate g-C_(3)N_(4)with high crystallinity and excellent photocatalytic properties,in which cheap sodium nitrite aqueous solution is utilized as a moderate etching agent.The compositions and physiochemical properties of the products were comprehensively investigated by X-ray diffraction,Fourier-transform infrared spectroscopy,ultraviolet visible diffuse reflectance spectroscopy,X-ray photoelectron spectroscopy,N2 adsorption–desorption,and electrochemical impedance spectroscopy measurements.In addition,ToF-SIMS(time-of-flight secondary ion mass spectrometry),a new surface analysis technology,was also used to determine the surface and structural characteristics of all samples.The obtained g-C_(3)N_(4)shows ideal high-crystallinity features and excellent charge transfer ability,leading to significantly improved Cr(VI)reduction activity under visible light.Moreover,there is only a low content of nitrite residue(63.3 mg g^(−1))in the final g-C_(3)N_(4)product,indicating that the method employing NaNO_(2),which is widely used in the food industry,is safe and waste-free.Therefore,the new controllable NaNO_(2)etching method is cleaner and more efficient than commonly-used corrosion approaches based on strong acids or strong oxidants,and thus affords a new strategy in the regulation and structural design of various catalysts.展开更多
Low-dimensional hybrid organic-inorganic metal halides(OIMHs)have been extensively investigated for their structural tunability and unique optoelectronic properties.However,the synthesis of highly photoluminescent lea...Low-dimensional hybrid organic-inorganic metal halides(OIMHs)have been extensively investigated for their structural tunability and unique optoelectronic properties.However,the synthesis of highly photoluminescent lead-free OIMHs remains challenging.To address this issue,we synthesized a series of hybrid OIMHs(DETA)_(3)InCl_(6):xSb^(3+)(DETA=diethylenetriamine,x=0-15%).With Sb^(3+)doping,the photoluminescence quantum yield(PLQY)is greatly improved from 4.84%to nearly 100%.Moreover,(DETA)_(3)InCl_(6):10%Sb^(3+)single crystals exhibit strong yellow broadband emission originating from selftrapped exciton(STE)radiative recombination.Interestingly,when Sb^(3+)doping is 0.005%,the single crystal doped Sb emits white light at an excitation wavelength of 365 nm with CIE coordinates of(0.35,0.36).We also explored the effect of Sb^(3+)dopants and STE state formation by DFT calculations and ultrafast transient absorption techniques.This research provides new insights into the design of high-performance photoluminescent materials based on hybrid metal halides.展开更多
基金supported by the National Natural Science Foundation of China(No.21590791,21771005,21425101 and 21931001)the Ministry of Science and Technology of China(2017YFA0205101 and 2017YFA0205104).
文摘Inorganic black-phase CsPbI_(3)perovskites(cubicα,tetragonalβand orthorhombicγ)have attracted immense attention due to their superior optical and optoelectronic properties.However,the black phase is metastable and spontaneously transforms into a non-optically active yellow phase(orthorhombicδ)as the temperature drops to room temperature or even lower.This severely inhibits its practical applications under light and driving voltage,and at varying temperatures.Here,we report a novel method to improve the stability ofγ-CsPbI_(3)nanowires in a wide temperature range.With an ordered mesoporous silica SBA-15 template,the CsPbI_(3)nanowires are confined into the channels and crystalize in theδphase,which can transform into theγphase under calcination at 623 K.Compared with the CsPbI_(3)obtained without SBA-15,theseγ-CsPbI_(3)nanowires are stable until 193 K,the lowest temperature record to date.The phase stability stems from the interfacial coordination of Pb and O,which acts as an“anchor”to suppress the distortion of the[PbI_(6)]^(4)−octahedron forγ-CsPbI_(3).Additionally,this protocol can be extended to mixed halide perovskites.The“anchor”in this work is also expected to shed light on intriguing studies on the phase stabilization of other functional materials.
基金supported by the National Natural Science Foundation of China(Grant No.51671136 and 51502172)the International Technological Collaboration Project of Shanghai(Grant No.17520710300)+2 种基金the AUFFNOVA-Project(Grant No.AUFF-E-2015-FLS-9-18)EU H2020 RISE 2016(MNR4SCell 734174 project)the Fundamental Research Funds for the Central Universities,China(YJ201893).
文摘As a promising visible-light-responsive catalyst,graphitic carbon nitride(g-C_(3)N_(4))has been widely used in environmental and energy applications owing to its unique semiconducting optoelectronic properties.However,the photocatalytic performance of bulk g-C_(3)N_(4)synthesized using N-containing precursors via a conventional thermal polycondensation process is generally limited by low crystallinity caused by incomplete polymerization.In addition to forced polymerization under high-pressure conditions,removing the unpolymerized and inactive part of bulk g-C_(3)N_(4)through controllable etching is another practical way to optimize its crystallinity.Therefore,we developed an economical and general method to fabricate g-C_(3)N_(4)with high crystallinity and excellent photocatalytic properties,in which cheap sodium nitrite aqueous solution is utilized as a moderate etching agent.The compositions and physiochemical properties of the products were comprehensively investigated by X-ray diffraction,Fourier-transform infrared spectroscopy,ultraviolet visible diffuse reflectance spectroscopy,X-ray photoelectron spectroscopy,N2 adsorption–desorption,and electrochemical impedance spectroscopy measurements.In addition,ToF-SIMS(time-of-flight secondary ion mass spectrometry),a new surface analysis technology,was also used to determine the surface and structural characteristics of all samples.The obtained g-C_(3)N_(4)shows ideal high-crystallinity features and excellent charge transfer ability,leading to significantly improved Cr(VI)reduction activity under visible light.Moreover,there is only a low content of nitrite residue(63.3 mg g^(−1))in the final g-C_(3)N_(4)product,indicating that the method employing NaNO_(2),which is widely used in the food industry,is safe and waste-free.Therefore,the new controllable NaNO_(2)etching method is cleaner and more efficient than commonly-used corrosion approaches based on strong acids or strong oxidants,and thus affords a new strategy in the regulation and structural design of various catalysts.
基金supported by the National Natural Science Foundation of China(22275075)the Natural Science Foundation of Jiangxi Province(20204BCJ22015 and 20202ACBL203001)the Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(20212BCD42018).
文摘Low-dimensional hybrid organic-inorganic metal halides(OIMHs)have been extensively investigated for their structural tunability and unique optoelectronic properties.However,the synthesis of highly photoluminescent lead-free OIMHs remains challenging.To address this issue,we synthesized a series of hybrid OIMHs(DETA)_(3)InCl_(6):xSb^(3+)(DETA=diethylenetriamine,x=0-15%).With Sb^(3+)doping,the photoluminescence quantum yield(PLQY)is greatly improved from 4.84%to nearly 100%.Moreover,(DETA)_(3)InCl_(6):10%Sb^(3+)single crystals exhibit strong yellow broadband emission originating from selftrapped exciton(STE)radiative recombination.Interestingly,when Sb^(3+)doping is 0.005%,the single crystal doped Sb emits white light at an excitation wavelength of 365 nm with CIE coordinates of(0.35,0.36).We also explored the effect of Sb^(3+)dopants and STE state formation by DFT calculations and ultrafast transient absorption techniques.This research provides new insights into the design of high-performance photoluminescent materials based on hybrid metal halides.
