In pursuit of more efficient and stable electrochemical energy storage materials,composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and...In pursuit of more efficient and stable electrochemical energy storage materials,composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties.Graphene oxide(GO),a two-dimensional material with an extremely high specific surface area and excellent conductivity,offers new possibilities for enhancing the electrochemical performance of metal oxides.In this work,we synthesized met-al-organic framework(MOF)and GO composites by regulating the amount of GO,and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process.Based on the electrochemical tests,the optimal amount of GO was determined.This research will provide new insights into and directions for designing and synthesizing metal oxide and graphene oxide composite materials with an ideal electro-chemical performance.展开更多
Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant d...Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant death syndrome.Additionally,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly needed.This work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)composite.The synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support material.In addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable manner.By analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ppm.Moreover,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical application.The results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.展开更多
Natural intercalation of the graphite oxide, obtained as a product of Hummer＇s method, via ultra-sonication of water dispersed graphite oxide has been carried out to obtain graphene oxide（GO） and thermally reduced ...Natural intercalation of the graphite oxide, obtained as a product of Hummer＇s method, via ultra-sonication of water dispersed graphite oxide has been carried out to obtain graphene oxide（GO） and thermally reduced graphene oxide（RGO）.Here we report the effect of metallic nitrate on the oxidation properties of graphite and then formation of metallic oxide（MO） composites with GO and RGO for the first time. We observed a change in the efficiency of the oxidation process as we replaced the conventionally used sodium nitrate with that of nickel nitrate Ni（NO_3）_2, cadmium nitrate Cd（NO_3）_2,and zinc nitrate Zn（NO_3）_2. The structural properties were investigated by x-ray diffraction and observed the successful formation of composite of MO–GO and MO–RGO（M = Zn, Cd, Ni）. We sought to study the effect on the oxidation process through optical characterization via UV-Vis spectroscopy and Fourier Transform Infrared（FTIR） spectroscopy.Moreover, Thermo Gravimetric Analysis（TGA） was carried out to confirm 〉 90% weight loss in each process thus proving the reliability of the oxidation cycles. We have found that the nature of the oxidation process of graphite powder and its optical and electrochemical characteristics can be tuned by replacing the sodium nitrate（NaNO_3） by other metallic nitrates as Cd（NO_3）_2, Ni（NO_3）_2, and Zn（NO_3）_2. On the basis of obtained results, the synthesized GO and RGO may be expected as a promising material in antibacterial activity and in electrodes fabrication for energy devices such as solar cell, fuel cell,and super capacitors.展开更多
This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coati...This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coating technique from GO and an aqueous solution of TiO2. A significant decrease in optical band gap was observed at the TiO2-GO compound compared to that of pure TiO2. Samples as prepared were characterized using XRD, SEM and UV-visible spectra. XRD analysis revealed the amorphous nature of the deposited layers. Scanning electron microscope reveals the dispersion of graphene nanofiles among titanium oxide nanoparticles distributed at the surface with an almost uniform size distribution. The band gap has been calculated and is around 2 eV after incorporation of Graphene oxide. The chemical bond C-Ti between the titanium oxide and graphene sheets is at the origin of this reduction.展开更多
Metal oxide semiconductor gas sensors offer high sensitivity and low-cost gas detection.However,low selectivity and poor stability are significant challenges associated with these sensors.In this study,we designed a s...Metal oxide semiconductor gas sensors offer high sensitivity and low-cost gas detection.However,low selectivity and poor stability are significant challenges associated with these sensors.In this study,we designed a sheet-like stacked zinc oxide(ZnO)nanomaterial using ZIF-67 and prepared the nanomaterial AGCZ-2 by doping with gold-modified graphene oxide(GO).This material demonstrates rapid and sensitive detection of low concentrations of carbon monoxide(CO)gas and exhibits excellent selectivity towards CO.The crystal structure,microstructure,elemental composition,and pore size of the material were characterized and analyzed using XRD,FESEM,EDS elemental analysis,TEM,and N2 adsorption-desorption techniques.The CO gas sensing performance of the sensor prepared in this study was tested,and the results showed that the AGCZ-2 sensor,operating at an optimal temperature of 260℃,had a response value of 5.84 for 50 ppm CO,with response and recovery times of 103 s and 84 s,respectively.In terms of selectivity,the response of the AGCZ-2 sensor to CO was 3.84 times that of the second most sensitive gas(hydrogen),indicating excellent selectivity towards CO over hydrogen.Additionally,the sensor exhibited good stability and repeatability,with a relative standard deviation of 2.27% for the response values to 5 ppm CO gas over five consecutive tests.Over a 28-day testing period,the sensor’s response to 5 ppm CO exhibited a decay rate of 5.22%,with a relative standard deviation of 2.41.展开更多
以生物废弃核桃壳作为原料,添加具备强吸附能力、高比表面积、高化学稳定性等优点的氧化石墨烯(GO),利用共沉淀法制备新型磁性氧化石墨烯生物炭(Fe_(3)O_(4)-GO-WSC)复合材料。通过FTIR、XRD、SEM、BET、UV-Vis等表征手段对复合材料的...以生物废弃核桃壳作为原料,添加具备强吸附能力、高比表面积、高化学稳定性等优点的氧化石墨烯(GO),利用共沉淀法制备新型磁性氧化石墨烯生物炭(Fe_(3)O_(4)-GO-WSC)复合材料。通过FTIR、XRD、SEM、BET、UV-Vis等表征手段对复合材料的组成、表面性质及磁性强度进行系统表征,并探究不同条件下复合材料对水体有机污染物亚甲基蓝(MB)的吸附效果。结果表明,将0.02 g Fe_(3)O_(4)-GO-WSC磁性复合材料加入10 mg/L MB溶液,吸附率为90.2%。经5次磁性分离,对MB吸附率为54.7%。复合材料对MB的吸附行为,与准二级动力学模型和Langmuir吸附等温模型有较好相关性,说明该吸附过程偏向于化学吸附,是单分子层吸附。展开更多
基金supported by the National Natural Science Foundation of China(51971157)Shenzhen Science and Technology Program(JCYJ20210324115412035,JCYJ202103-24123202008,JCYJ20210324122803009 and ZDS-YS20210813095534001)Guangdong Foundation for Basic and Applied Basic Research Program(2021A1515110880).
文摘In pursuit of more efficient and stable electrochemical energy storage materials,composite materials consisting of metal oxides and graphene oxide have garnered significant attention due to their unique structures and exceptional properties.Graphene oxide(GO),a two-dimensional material with an extremely high specific surface area and excellent conductivity,offers new possibilities for enhancing the electrochemical performance of metal oxides.In this work,we synthesized met-al-organic framework(MOF)and GO composites by regulating the amount of GO,and successfully prepared composites of metal oxides supported by nitrogen-doped carbon frameworks and GO through a simple one-step calcination process.Based on the electrochemical tests,the optimal amount of GO was determined.This research will provide new insights into and directions for designing and synthesizing metal oxide and graphene oxide composite materials with an ideal electro-chemical performance.
基金supported by the National Research Foundation of Korea(NRF)under Grant Nos.NRF-2017M3A9F1031229,NRF2017R1E1A1A01075439,and NRF-2019R1C1C1005668The Korea Environment Industry&Technology Institute(KEITI)through its Ecological Imitation-based Environmental Pollution Management Technology Development Project+1 种基金funded by the Korea Ministry of Environment(MOE)(2019002800009)And Korea University(Grant No.K2111511)。
文摘Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by automobiles.It is related to various respiratory diseases such as pneumonia and sudden infant death syndrome.Additionally,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly needed.This work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)composite.The synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support material.In addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable manner.By analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ppm.Moreover,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical application.The results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.
文摘Natural intercalation of the graphite oxide, obtained as a product of Hummer＇s method, via ultra-sonication of water dispersed graphite oxide has been carried out to obtain graphene oxide（GO） and thermally reduced graphene oxide（RGO）.Here we report the effect of metallic nitrate on the oxidation properties of graphite and then formation of metallic oxide（MO） composites with GO and RGO for the first time. We observed a change in the efficiency of the oxidation process as we replaced the conventionally used sodium nitrate with that of nickel nitrate Ni（NO_3）_2, cadmium nitrate Cd（NO_3）_2,and zinc nitrate Zn（NO_3）_2. The structural properties were investigated by x-ray diffraction and observed the successful formation of composite of MO–GO and MO–RGO（M = Zn, Cd, Ni）. We sought to study the effect on the oxidation process through optical characterization via UV-Vis spectroscopy and Fourier Transform Infrared（FTIR） spectroscopy.Moreover, Thermo Gravimetric Analysis（TGA） was carried out to confirm 〉 90% weight loss in each process thus proving the reliability of the oxidation cycles. We have found that the nature of the oxidation process of graphite powder and its optical and electrochemical characteristics can be tuned by replacing the sodium nitrate（NaNO_3） by other metallic nitrates as Cd（NO_3）_2, Ni（NO_3）_2, and Zn（NO_3）_2. On the basis of obtained results, the synthesized GO and RGO may be expected as a promising material in antibacterial activity and in electrodes fabrication for energy devices such as solar cell, fuel cell,and super capacitors.
文摘This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coating technique from GO and an aqueous solution of TiO2. A significant decrease in optical band gap was observed at the TiO2-GO compound compared to that of pure TiO2. Samples as prepared were characterized using XRD, SEM and UV-visible spectra. XRD analysis revealed the amorphous nature of the deposited layers. Scanning electron microscope reveals the dispersion of graphene nanofiles among titanium oxide nanoparticles distributed at the surface with an almost uniform size distribution. The band gap has been calculated and is around 2 eV after incorporation of Graphene oxide. The chemical bond C-Ti between the titanium oxide and graphene sheets is at the origin of this reduction.
基金funded by the National Basic Research Program of China(grant no.2022YFB3206803)the National Science Foundation of China Project(grant numbers 62174163).
文摘Metal oxide semiconductor gas sensors offer high sensitivity and low-cost gas detection.However,low selectivity and poor stability are significant challenges associated with these sensors.In this study,we designed a sheet-like stacked zinc oxide(ZnO)nanomaterial using ZIF-67 and prepared the nanomaterial AGCZ-2 by doping with gold-modified graphene oxide(GO).This material demonstrates rapid and sensitive detection of low concentrations of carbon monoxide(CO)gas and exhibits excellent selectivity towards CO.The crystal structure,microstructure,elemental composition,and pore size of the material were characterized and analyzed using XRD,FESEM,EDS elemental analysis,TEM,and N2 adsorption-desorption techniques.The CO gas sensing performance of the sensor prepared in this study was tested,and the results showed that the AGCZ-2 sensor,operating at an optimal temperature of 260℃,had a response value of 5.84 for 50 ppm CO,with response and recovery times of 103 s and 84 s,respectively.In terms of selectivity,the response of the AGCZ-2 sensor to CO was 3.84 times that of the second most sensitive gas(hydrogen),indicating excellent selectivity towards CO over hydrogen.Additionally,the sensor exhibited good stability and repeatability,with a relative standard deviation of 2.27% for the response values to 5 ppm CO gas over five consecutive tests.Over a 28-day testing period,the sensor’s response to 5 ppm CO exhibited a decay rate of 5.22%,with a relative standard deviation of 2.41.
文摘以生物废弃核桃壳作为原料,添加具备强吸附能力、高比表面积、高化学稳定性等优点的氧化石墨烯(GO),利用共沉淀法制备新型磁性氧化石墨烯生物炭(Fe_(3)O_(4)-GO-WSC)复合材料。通过FTIR、XRD、SEM、BET、UV-Vis等表征手段对复合材料的组成、表面性质及磁性强度进行系统表征,并探究不同条件下复合材料对水体有机污染物亚甲基蓝(MB)的吸附效果。结果表明,将0.02 g Fe_(3)O_(4)-GO-WSC磁性复合材料加入10 mg/L MB溶液,吸附率为90.2%。经5次磁性分离,对MB吸附率为54.7%。复合材料对MB的吸附行为,与准二级动力学模型和Langmuir吸附等温模型有较好相关性,说明该吸附过程偏向于化学吸附,是单分子层吸附。
