In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method...In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer.Functionalization control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD.Notably,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting MXene.It improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2.This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.展开更多
Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene base...Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.展开更多
Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics.However,the low Seebeck coefficient and heat-...Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics.However,the low Seebeck coefficient and heat-to-electricity conversion efficiency hinder further application.In this paper,we designed a high-performance thermally chargeable supercapacitor device composed of ZnMn_(2)O_(4)@Ti_(3)C_(2)T_(x)MXene composites(ZMO@Ti_(3)C_(2)T_(x) MXene)electrode and UIO-66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro-propylene ionogel electrolyte,which realized the thermoelectric conversion and electrical energy storage at the same time.This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K^(−1),thermal voltage of 243 mV,and outstanding heat-to-electricity conversion efficiency of up to 6.48%at the temperature difference of 4.4 K.In addition,this device showed excellent charge–discharge cycling stability at high-temperature differences(3 K)and low-temperature differences(1 K),respectively.Connecting two thermally chargeable supercapacitor units in series,the generated output voltage of 500 mV further confirmed the stability of devices.When a single device was worn on the arm,a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.展开更多
Direct-Z-scheme g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)photocatalyst with giant internal electric field was prepared by onestep aqueous sonication self-assembly method using g-C_(3)N_(4)and MXene of Ti_(3)C_(2)as the source ...Direct-Z-scheme g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)photocatalyst with giant internal electric field was prepared by onestep aqueous sonication self-assembly method using g-C_(3)N_(4)and MXene of Ti_(3)C_(2)as the source materials.The chemical composition and structure of the catalysts was characterized by FT-IR,XRD,SEM,TEM,and XPS.The XPS characterization indicated that Ti_(3)C_(2)was partially oxidized to TiO_(2)during the composite process.As a result,an efficient direct-Z-scheme heterojunction structure consisting of the g-C_(3)N_(4)and TiO_(2)with Ti_(3)C_(2)as an electron bridge was constructed.The photocatalytic performance of the prepared catalysts was evaluated by degrading the Rhodamine B(RhB)wastewater.Compared with the single g-C_(3)N_(4),the g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)composite photocatalyst exhibited efficient and stable photocatalytic degradation ability,with a degradation efficiency as high as 99.2%for RhB under optimal conditions(2%Ti_(3)C_(2),pH=3).The high degradation performance of g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)for RhB was attributed to the combination of Ti_(3)C_(2),TiO_(2),and g-C_(3)N_(4)components,forming a direct-Z-scheme heterojunction with a high-speed electron transport channel structure.The role of Z-scheme heterojunctions in electron transport is verified by photoelectrochemical characterization,along with photoluminescence(PL).Our research provides a simple method to design photocatalysts by constructing direct-Z-scheme electron transport channels for highly efficient treatment of dye wastewater.展开更多
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT)(No. 2021R1I1A1A0105621313, No. 2022R1F1A1074441, No. 2022K1A3A1A20014496, and No. 2022R1F1A1074083)supported by the Ministry of Education Funding (No. RIS 2021-004)supported by the Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea (RS-2023-00284318).
文摘In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer.Functionalization control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD.Notably,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting MXene.It improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2.This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.
基金supported by National Natural Science Foundation of China(51672308,51972025,61888102,and 62004187).
文摘Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.
基金supported by the National Natural Science Foundation of China(52273256)Beijing Municipal Natural Science Foundation(L223006)Beijing Institute of Technology Research Found Program for Young Scholars.
文摘Thermally chargeable supercapacitors can collect low-grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics.However,the low Seebeck coefficient and heat-to-electricity conversion efficiency hinder further application.In this paper,we designed a high-performance thermally chargeable supercapacitor device composed of ZnMn_(2)O_(4)@Ti_(3)C_(2)T_(x)MXene composites(ZMO@Ti_(3)C_(2)T_(x) MXene)electrode and UIO-66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro-propylene ionogel electrolyte,which realized the thermoelectric conversion and electrical energy storage at the same time.This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K^(−1),thermal voltage of 243 mV,and outstanding heat-to-electricity conversion efficiency of up to 6.48%at the temperature difference of 4.4 K.In addition,this device showed excellent charge–discharge cycling stability at high-temperature differences(3 K)and low-temperature differences(1 K),respectively.Connecting two thermally chargeable supercapacitor units in series,the generated output voltage of 500 mV further confirmed the stability of devices.When a single device was worn on the arm,a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.
基金supported by the National Natural Science Foundation of China(22078138)the Natural Science Foundation of Jiangxi Province(20202ACBL203009).
文摘Direct-Z-scheme g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)photocatalyst with giant internal electric field was prepared by onestep aqueous sonication self-assembly method using g-C_(3)N_(4)and MXene of Ti_(3)C_(2)as the source materials.The chemical composition and structure of the catalysts was characterized by FT-IR,XRD,SEM,TEM,and XPS.The XPS characterization indicated that Ti_(3)C_(2)was partially oxidized to TiO_(2)during the composite process.As a result,an efficient direct-Z-scheme heterojunction structure consisting of the g-C_(3)N_(4)and TiO_(2)with Ti_(3)C_(2)as an electron bridge was constructed.The photocatalytic performance of the prepared catalysts was evaluated by degrading the Rhodamine B(RhB)wastewater.Compared with the single g-C_(3)N_(4),the g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)composite photocatalyst exhibited efficient and stable photocatalytic degradation ability,with a degradation efficiency as high as 99.2%for RhB under optimal conditions(2%Ti_(3)C_(2),pH=3).The high degradation performance of g-C_(3)N_(4)/Ti_(3)C_(2)/TiO_(2)for RhB was attributed to the combination of Ti_(3)C_(2),TiO_(2),and g-C_(3)N_(4)components,forming a direct-Z-scheme heterojunction with a high-speed electron transport channel structure.The role of Z-scheme heterojunctions in electron transport is verified by photoelectrochemical characterization,along with photoluminescence(PL).Our research provides a simple method to design photocatalysts by constructing direct-Z-scheme electron transport channels for highly efficient treatment of dye wastewater.
