Formaldehyde(HCHO) is widely known as an indoor air pollutant,and the monitoring of the gas has significant importance.However,most HCHO sensing materials do not have low detection limits and operate at high temperatu...Formaldehyde(HCHO) is widely known as an indoor air pollutant,and the monitoring of the gas has significant importance.However,most HCHO sensing materials do not have low detection limits and operate at high temperatures.Herein,two-dimensional(2D) mesoporous ultrathin SnO_(2) modified with nitrogen-doped graphene quantum dots(N-GQDs) was synthesized.The N-GQDs/SnO_(2) nanocomposite demonstrated high efficiency for HCHO detection.With the addition of 1.00 wt%N-GQDs,the response(Ra/Rg) of SnO_(2) gas sensor increased from 120 to 361 at 60℃ for the detection of 10×10^(-6) HCHO.In addition,the corresponding detection limit was as low as 10×10^(-9).Moreover,the sensor exhibited excellent selectivity and stability for the detection of HCHO.The enhanced sensing performance was attributed to both the large specific surface area of SnO_(2) and electron regulation of N-GQDs.Therefore,this study presents a novel HCHO sensor,and it expands the research and application potential of GQDs nanocomposites.展开更多
Comprehensive consideration of structural and electronic sensitization is of significant importance for rational design and assembly of high-performance gas sensors based on metal oxides.In this work,hierarchically me...Comprehensive consideration of structural and electronic sensitization is of significant importance for rational design and assembly of high-performance gas sensors based on metal oxides.In this work,hierarchically mesoporous ZnO nanosheets are synthesized via a hydrothermal method followed by calcination.Material characterization reveals polycrystalline feature of these ZnO nanosheets rich in mesopores and defects.Gas sensing performance of as-synthesized ZnO nanosheets was sys-tematically investigated,taking formaldehyde as probe molecules.Compared with commercial ZnO nanoparticles,ZnO nanosheets exhibited enhanced formaldehyde sensing properties,including lower operation temperature,higher sensitivity,faster response,and smaller detection limit.Notably,the response(S=227.4)of ZnO nanosheets to 200×10^(-6)formaldehyde is about 17 times larger than that of ZnO nanoparticles(S=13.5).Excluding effects of grain size and surface area,enhanced sensing properties,especially response value,are credited in large part to synergistic actions of surface defects,grain boundaries,as well as unique structural advantage of ZnO nanosheets.Furthermore,this work offers a guideline for boosting performance of metal oxide-based gas sensors via surface defect control and grain boundary construction.展开更多
Graphene quantum dots(GQDs)have both the properties of graphene and semiconductor quantum dots,and exhibit stronger quantum confinement effect and boundary effect than graphene.In addition,the band gap of GQDs will tr...Graphene quantum dots(GQDs)have both the properties of graphene and semiconductor quantum dots,and exhibit stronger quantum confinement effect and boundary effect than graphene.In addition,the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization,which can be dispersed in common solvents and compounded with solid materials.In this work,the SnO2 nanosheets were prepared by hydrothermal method.As the sensitizer,nitrogen-doped graphene quantum dots(N-GQDs)were prepared and composited with SnO2 nanosheets.Sensing performance of pristine SnO2 and N-GQDs/SnO2 were investigated with HCHO as the target gas.The response(Ra/Rg)of0.1%N-GQDs/SnO2 was 256 for 100 ppm HCHO at 60℃,which was about 2.2 times higher than pristine SnO2 nanosheet.In addition,the material also had excellent selectivity and low operation temperature.The high sensitivity of N-GQDs/SnO2 was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs.This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.62071300 and51702212)the Science and Technology Commission of Shanghai Municipality (Nos.18511110600,19ZR1435200,and 20490761100)+2 种基金the Innovation Program of Shanghai Municipal Education Commission (No.2019-01-07-00-07-E00015)the Program of Shanghai Academic/Technology Research Leader (No.19XD1422900)the Chenguang Scholar Project of Shanghai Education Commission (No. 19CG52) and Cross-Program of Medical & Engineering。
文摘Formaldehyde(HCHO) is widely known as an indoor air pollutant,and the monitoring of the gas has significant importance.However,most HCHO sensing materials do not have low detection limits and operate at high temperatures.Herein,two-dimensional(2D) mesoporous ultrathin SnO_(2) modified with nitrogen-doped graphene quantum dots(N-GQDs) was synthesized.The N-GQDs/SnO_(2) nanocomposite demonstrated high efficiency for HCHO detection.With the addition of 1.00 wt%N-GQDs,the response(Ra/Rg) of SnO_(2) gas sensor increased from 120 to 361 at 60℃ for the detection of 10×10^(-6) HCHO.In addition,the corresponding detection limit was as low as 10×10^(-9).Moreover,the sensor exhibited excellent selectivity and stability for the detection of HCHO.The enhanced sensing performance was attributed to both the large specific surface area of SnO_(2) and electron regulation of N-GQDs.Therefore,this study presents a novel HCHO sensor,and it expands the research and application potential of GQDs nanocomposites.
基金financially supported by the National Natural Science Foundation of China(Nos.21601094,21401139 and 71804123)Tianjin Municipal Education Commission(No.2018KJ271)
文摘Comprehensive consideration of structural and electronic sensitization is of significant importance for rational design and assembly of high-performance gas sensors based on metal oxides.In this work,hierarchically mesoporous ZnO nanosheets are synthesized via a hydrothermal method followed by calcination.Material characterization reveals polycrystalline feature of these ZnO nanosheets rich in mesopores and defects.Gas sensing performance of as-synthesized ZnO nanosheets was sys-tematically investigated,taking formaldehyde as probe molecules.Compared with commercial ZnO nanoparticles,ZnO nanosheets exhibited enhanced formaldehyde sensing properties,including lower operation temperature,higher sensitivity,faster response,and smaller detection limit.Notably,the response(S=227.4)of ZnO nanosheets to 200×10^(-6)formaldehyde is about 17 times larger than that of ZnO nanoparticles(S=13.5).Excluding effects of grain size and surface area,enhanced sensing properties,especially response value,are credited in large part to synergistic actions of surface defects,grain boundaries,as well as unique structural advantage of ZnO nanosheets.Furthermore,this work offers a guideline for boosting performance of metal oxide-based gas sensors via surface defect control and grain boundary construction.
基金the financial supports from the National Natural Science Foundation of China(Nos.51602197,51771121 and 51702212)Shanghai Municipal Science and Technology Commission(Nos.19ZR1435200,18511110600 and 19JC1410402)+1 种基金Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00015)Shanghai Academic/Technology Research Leader Program(No.19XD1422900)。
文摘Graphene quantum dots(GQDs)have both the properties of graphene and semiconductor quantum dots,and exhibit stronger quantum confinement effect and boundary effect than graphene.In addition,the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization,which can be dispersed in common solvents and compounded with solid materials.In this work,the SnO2 nanosheets were prepared by hydrothermal method.As the sensitizer,nitrogen-doped graphene quantum dots(N-GQDs)were prepared and composited with SnO2 nanosheets.Sensing performance of pristine SnO2 and N-GQDs/SnO2 were investigated with HCHO as the target gas.The response(Ra/Rg)of0.1%N-GQDs/SnO2 was 256 for 100 ppm HCHO at 60℃,which was about 2.2 times higher than pristine SnO2 nanosheet.In addition,the material also had excellent selectivity and low operation temperature.The high sensitivity of N-GQDs/SnO2 was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs.This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.
